If you have pectus and you're skinny, you already know the loop: you train, nothing fills out, the dip looks worse next to your ribs, and you give up on eating because you're "just not hungry." This is the program that breaks that loop. It's the exact way I got calories into a body that didn't want them - and it's built on the best nutrition science there is, not on gym-bro guesswork.

Here's the honest promise. I can't turn you into a bodybuilder from a document. But I can give you the one thing almost every skinny pectus guy is missing: a way to reliably eat more than you burn, week after week, even when your appetite is working against you. Do that, add the training, and your chest fills out. The frame stops looking hollow. That's the whole game.

How this is built

The backbone of the science here is The Muscle and Strength Pyramid: Nutrition by Dr. Eric Helms and colleagues - the most rigorous, plain-spoken evidence-based nutrition framework available.¹⁰ I've taken its five-level hierarchy - energy balance first, then macros, then the smaller stuff - and rebuilt it for one specific person: someone with pectus who needs to gain, not lose. On top of that I've layered the pectus research on why you're built the way you are, and my own decade of doing this in my own kitchen.

The order matters

Read it front to back once. The levels are stacked on purpose: the stuff at the bottom (total calories) decides 90% of your result, and the stuff near the top (supplements, meal timing) is fine-tuning that means nothing if the base is wrong.¹⁰ Most skinny guys obsess over the top - the "best" mass-gainer, the perfect post-workout window - while completely missing the base. We're going to do it the other way around. The next section shows that hierarchy as a single picture.

• Part 1 sets your calorie target - the single most important number in this whole document.
• Part 2 splits those calories into protein, carbs, and fat so the weight you gain is muscle, not just fat.
• Part 3 is the part no generic bulking guide has: how to actually get that food down when your appetite quits at half a plate. This is where the blender comes in.
• Part 4 puts it on a schedule - how to train so the food becomes muscle, a 12-week plan, and a full worked example.
• Part 5 is how you actually stick with it: tracking, sleep, the mental game, staying healthy, the mistakes that sink most skinny gainers, and how to do it all on a budget without wrecking your gut.

Here's the whole guide in one picture. Like the framework it's built on, this is a pyramid: the widest band at the bottom is the most important thing, and each band above it matters a little less.¹⁰ Build from the base up. Nail the bottom two bands and you'll gain, even if you ignore everything above them. Obsess over the tip while your base is broken and you'll get nowhere - which is exactly the trap most skinny guys fall into.

Read the bands top to bottom and you'll notice the money is all at the base. Calories decide whether you gain at all. Protein and macros decide whether that gain is muscle that fills your chest or just fat. Everything above - food quality, timing, supplements - is real but small, and worthless if the base isn't handled first. So that's the order we work in, and it's the order this guide is written in.

Let me say the thing nobody tells you when you're researching how to fix a sunken chest: being underweight makes pectus look worse than it is. A hollow in the sternum reads as a much deeper crater when there's no muscle around it and the ribs are the most prominent thing on your torso. Put pecs, serratus, and upper-back mass around that same dip and the eye stops going straight to the hole. The bone hasn't changed yet - but the picture has.

This isn't a cope, and it isn't the whole fix either. The vacuum bell, the training, and the breathing work all still matter for the structure itself. But food is the lever nobody's pulling. You can wear the bell perfectly and train four days a week, and if you're eating at maintenance in a skinny body, you'll build almost nothing to fill the frame. Muscle is made of the food you eat in a surplus. No surplus, no new tissue - that's not motivation, it's biochemistry.¹⁰

"But I don't want to just get fat"

You won't - not if you do it the way this document lays out. There's a myth that gaining weight means blowing up with fat and then cutting it off. The research says the opposite: gain at the right pace, hit your protein, and keep training, and most of what you add is lean tissue, especially in your first year or two of proper training.¹⁶¹⁹ The people who get fat are the ones who force-feed way too fast, or who eat junk with no protein and never lift. We're going to avoid both.

And here's the freeing part, backed by data across athletic populations: carrying a bit more body fat does not blunt your ability to build muscle.¹⁰²⁵ The fear of "getting fat" keeps skinny guys under-eating for years. You have room to eat. Let's use it.

You're not imagining it, and it's not just "bad genetics" in a vague sense. There's a real, measurable pattern here, and understanding it takes the shame out of it.

The build comes with the chest

Pectus excavatum tends to travel with a particular body type - tall, long-limbed, narrow-framed, low body fat. It's part of the same connective-tissue picture that produces the caved-in sternum in the first place. When researchers actually measured it, pectus patients were lighter and shorter than the general population before treatment. In one study of Nuss-procedure patients, both height and weight sat below the normal range going in, then normalized within about two years of correction - and the degree of that under-development tracked with how severe the chest deformity was on CT.² One leading theory: the chest compresses the heart and lungs enough to hold back circulation and general development.²³

So the skinny frame isn't a personal failure. It's part of the condition. That's good news, because it means it responds to the same lever everyone else's body does - food and training - once you stop fighting your own appetite blindly and start doing it on purpose.

The appetite problem is real too

On top of the build, most skinny pectus guys genuinely don't feel hunger the way heavier people do. You fill up on half a meal. You forget to eat. Big plates feel like a chore. None of that is weakness - appetite is regulated by your brain and hormones, and everyone has a natural "set point" where hunger sits.¹⁰ People near the low end of their body-fat range are actually worse at ramping hunger up than heavier people are at dialing it down.¹⁰ In plain terms: your body defends being lean. It nudges you to eat less, burn more, and stay exactly where you are.

There's even a name for the extreme version. Some people are wired to burn off a surprising amount of any extra food through fidgeting, restlessness, and unconscious movement - so-called non-exercise activity. In one controlled overfeeding study, people ate the same 1,000 extra calories a day for eight weeks and gained anywhere from under a pound of fat to nearly ten, because their bodies quietly burned off wildly different amounts.²¹ If you've ever felt like a "hard gainer" who can't put on weight no matter what, you may be one of these high responders. It's not in your head.

This is the base of the pyramid and the only section you truly cannot skip. Long-term changes in body weight come down to one thing: the energy you take in from food versus the energy you burn.¹⁰ To gain weight you have to eat more than you burn - a calorie surplus. There is no food, supplement, or trick that builds new tissue without one. Everything else in this document is about doing that surplus well.

"I eat a lot" is almost always wrong

Every skinny guy I've coached swears he eats a ton. Almost every time, when we actually count, he doesn't - not consistently, not enough, not every day. Your memory of a huge weekend meal hides four days of barely eating. Until you've measured it, "I eat a lot" is a feeling, not a number. The whole point of Section 2 is to replace the feeling with a number you can move on purpose.

How big should the surplus be?

Bigger is not better. Gain too fast and most of the extra weight is fat, not muscle - study after study shows that pushing past roughly 2% of your body weight per month just adds fat without adding more muscle or strength.¹⁷¹⁸¹⁹ The surplus doesn't force muscle on you; it just gives your training the raw material to build. Think of it as permission to grow, not a cattle prod.²⁰

A sensible target rate of gain, drawn straight from the research, depends on how trained you are:

Adapted from the rate-of-weight-gain guidance in The Muscle and Strength Pyramid: Nutrition.¹⁰ Notice these are monthly, not weekly - muscle grows slowly, and honest expectations here are what keep you from over-eating into fat.

If you're a skinny beginner, you're in the best possible spot: you can gain at the top of that range and most of it can be muscle.¹⁶ A 150 lb beginner aiming for ~1.5% a month is targeting a little over 2 lb of gain per month - roughly half a pound a week. That's the number to build your calories around.

Turning a target into calories

Here's the simple math from the book. Because roughly 3,500 calories sits behind a pound of weight,¹⁴ a rough starting surplus is:

That's a starting point, not a guarantee. Your real result depends on your own metabolism, and - as we saw - some bodies quietly burn off part of any surplus.²¹²² So you'll start here, watch the scale over 2–3 weeks, and adjust. Which means first you need your maintenance number. That's Section 2.

Maintenance is the number of calories that keeps your weight exactly where it is. Once you know it, your gain target is simply maintenance plus the surplus from Section 1. There are two ways to find it: a quick estimate, and the accurate way.

The quick estimate

Use this to get started today. It's rough, but it gets you moving:¹⁰

That activity range is wide on purpose - two people the same weight can differ by hundreds of calories.¹⁰ So treat the estimate as a launch pad, not gospel. The accurate method is what actually dials you in.

The accurate way: track and watch

The only truly accurate maintenance number is your own real-world data.¹⁰ For two weeks, without changing how you eat, do two things:

• Weigh yourself every morning - first thing, after the bathroom, before eating or drinking, same amount of clothing. Take the weekly average, not any single day. Daily weight bounces 1–2% from water and food alone; the average is the real signal.¹⁰
• Log everything you eat with a food scale and an app, as honestly as you can. Yes, it's tedious. You only have to do it long enough to learn your numbers - a few weeks, not forever.

Then compare week 1's average weight to week 2's. Roughly stable? Your average daily calories are your maintenance. Drifting up or down? Your maintenance is a bit below or above what you ate. Each pound of weekly change ≈ 500 cal/day off maintenance.¹⁰¹⁴

Can't stand tracking? Use appetite instead

Tracking isn't for everyone, and if you have any history of disordered eating it may not be right for you - talk to a professional first. There's a workable backup: rate how full you feel after meals on a 1 (starving) to 7 (stuffed) scale. Landing around 4–6 most of the time tends to put you in a modest surplus.¹⁰ For gaining, you're deliberately aiming to sit fuller than feels natural - and Part 3 is all about how to do that when "full" arrives way too early.

Calories decide whether you gain weight. Macros - protein, carbs, and fat - decide what that weight is. Get protein right and the surplus turns into muscle that fills your frame. Get it wrong and you just get softer. Protein is the one macro that's literally the building material of muscle, so it comes first.³¹

How much

You don't need the mountain of protein the supplement industry sells you. The research is clear: gains in muscle keep climbing with protein up to about 1.6 grams per kilogram of bodyweight per day - roughly 0.7 grams per pound - and then flatten out. Beyond that, more protein does almost nothing extra.³¹³²

Where to get it

Foods high in protein for their calories: chicken, turkey, lean beef and pork, fish (including the tinned kind - more on that in Section 7), eggs, Greek yogurt and other dairy, tofu and soy, beans and lentils, and protein powder. You do not need animal protein specifically - vegans build muscle and strength just as well when total protein is sufficient and comes from a variety of sources across the day.³¹

One note that matters for skinny guys: protein is filling. That's great for people trying to lose weight and a problem for you. So while you must hit your protein target, you don't want to overshoot it massively and crowd out the calorie-dense carbs and fats that make hitting a surplus easy. Hit the band, then let carbs and fat fill the rest.

Once protein is set, carbs and fat make up the rest of your calories. For a skinny gainer these two are your best friends, because they're where easy, dense calories live. There's a common instinct to fear carbs or fear fat - ignore it. You need both, and you need plenty.

Fat - keep a floor, then eat freely

Fat supports your hormones, absorbs key vitamins, and packs the most calories per gram of anything you eat (9 per gram vs 4 for carbs and protein) - which makes it perfect for gaining.¹⁰ The research sets a practical minimum around 40–60 grams a day to keep hormones like testosterone healthy.¹⁰ For gaining you'll comfortably clear that. Lean on the calorie-dense fats: olive oil, nut butters, whole eggs, full-fat dairy, nuts, avocado, oily fish.

Carbs - fuel the training, fill the surplus

Carbs fuel your workouts and refill muscle glycogen so you can train hard enough to justify the surplus.¹⁰ Aim for at least 2 grams per kg of bodyweight in a surplus, and honestly, more is fine and often easier.¹⁰ Carbs are the least filling macro per calorie, so they're your main tool for hitting a big number: rice, oats, pasta, bread, potatoes, fruit, juice, milk.

Notice what this means: your macro split for gaining is naturally the opposite of a diet. Where a dieter squeezes fat and carbs down, you let them run. That's the entire mindset shift - and it leads straight into Part 3, where we make eating that much actually possible.

This is the section this whole program exists for. Every other bulking guide tells you the numbers and then leaves you alone with a plate you can't finish. The numbers are the easy part. The hard part - the part that has beaten you before - is getting that food into a body that says "no thanks" at half a meal. Let's fix it with strategy instead of willpower.

The insight that changes everything

Here's the exact move, and it's counterintuitive: to gain weight with a low appetite, do the opposite of nearly every "healthy eating" rule. The nutrition science is blunt about this. If your goal is to gain and your appetite is low or your metabolism runs hot, you should deliberately reduce how full your food makes you: eat more calorie-dense, less-filling foods, ease off excessive activity if your lifestyle allows, and lean on shakes and liquid calories - which are far less filling than solid food.¹⁰²⁶

Why liquid calories are your cheat code

This is the single most useful fact for a skinny gainer. Your body barely registers calories you drink. When you eat solid food, your gut and brain sense the fullness and you naturally eat less later. Drinks don't trigger that same brake - the calories go down and your appetite hardly compensates.²⁶²⁷²⁸ A shake with 700 calories can slide down in two minutes and leave you barely fuller. Try to eat those same 700 calories as chicken and rice and you'll be stuffed for hours. That's not a loophole - it's physiology, and it's why the blender in Section 6 is non-negotiable.

Energy density: small food, big calories

Fullness is driven largely by the volume and weight of food, not its calories.³⁰ A big bowl of salad and a handful of nuts can have the same calories, but the salad fills your stomach and the nuts don't. So for gaining, you systematically pick the energy-dense version of everything: whole milk over skim, olive oil on your rice, nut butter on your toast, dried fruit over fresh, the fattier cut of meat. Same eating effort, far more calories. Section 8 is a full list.

More meals, not bigger ones

If one big plate defeats you, stop trying to win that fight. Spreading the same calories across more, smaller meals - up to five or six a day - is a proven way to get more total food down when fullness is your limit. Eating more frequently is linked to greater hunger and higher total intake, which is exactly what you want here (it's why offseason bodybuilders traditionally eat around six times a day).¹⁰ Three "meals" plus two shakes and a snack is far easier to finish than three enormous plates.

If you buy one thing after reading this program, buy a blender. Not a supplement, not a mass-gainer tub - a blender. For a skinny pectus guy with a low appetite, it is the highest-leverage $40 you will ever spend. Drinking your calories is the easiest way on earth to hit a surplus, and this is how I've done it for years.

Everything in Section 5 points here. Liquid calories barely fill you up,²⁶ a blender lets you pack a genuinely huge amount of dense food into one drinkable glass, and a homemade shake beats any commercial mass-gainer on cost, quality, and control. You decide what goes in. You can hit 600–1,000 calories and 40+ grams of protein in something that goes down in the time it takes to watch a video.

The formula

Every good gainer shake is the same five slots. Build your own by picking from each:

Three shakes to start with

I'm not writing this from theory. I have pectus, I've always had a low appetite, and I spent years frustrated that I couldn't fill out my frame. Here's what actually works in my own kitchen - the real, unglamorous version.

Sardines are the skinny guy's secret weapon

I eat sardines constantly, and I recommend them to almost everyone I coach. Here's why they're close to a perfect food for a pectus gainer: a tin is packed with protein and calorie-dense fats in a tiny volume, it needs zero cooking, it's cheap, it keeps in a cupboard for years, and it's loaded with omega-3 fats - which research links to better muscle-protein response on top of their general health benefits.⁴⁷ When my appetite is low, I don't have to face a giant plate - I just open a tin. Two tins over a day is an easy 400+ dense calories and 40+ grams of protein you barely have to chew.

I blend a lot of my food

This is the honest core of how I hit my numbers: when I can't eat enough, I drink it. On low-appetite days a big share of my calories comes through the blender - the shakes in Section 6, plus blended real meals when solid food feels like too much work. It's not exciting, but it's the difference between hitting my surplus and missing it by 600 calories like I used to. The blender turns "I'm not hungry" from a wall into a shrug.

I eat on a schedule, not on hunger

The biggest mental shift I made: I stopped waiting to feel hungry. If you eat only when your appetite tells you to, you will never gain, because your appetite is set to keep you skinny.¹⁰ So I eat by the clock instead - set meals and set shake times, whether I "feel like it" or not. Some days the last few hundred calories are a job I just do, the same way I'd do a set at the gym. That discipline, more than any single food, is what changed my body.

This is your shopping and swapping reference. The whole idea from Section 5 is energy density - the most calories for the least fullness.³⁰ Build your meals and shakes from the left column, and swap the "diet" version of any food for the dense version whenever you can.

The best dense foods for gaining

Cheap staples that do the heavy lifting

• Whole milk - the classic skinny-guy tool. Calorie-dense, drinkable, cheap, high protein. Drinking a litre a day is an easy ~600 extra calories.
• Oats - blend into shakes raw or cook them; huge calories for pennies.
• Peanut butter - ~190 calories in two tablespoons; add it to shakes, toast, oats.
• Rice and pasta - cook a big batch, drizzle oil over it, eat off it all week.
• Tinned fish - the no-cook protein and fat bomb from Section 7.
• Eggs - whole eggs (not just whites - the yolk holds the calories and nutrients).
• Bananas and dates - dense, blendable, portable carbs.

Easy dense swaps

This is upper-pyramid stuff - it matters far less than total calories and protein, so don't let it distract you from the base. But used well, timing makes eating enough easier, which for a low-appetite gainer is the whole point.

How many meals

Meal timing barely moves body composition on its own - the myth that frequent small meals "stoke your metabolism" was disproven long ago.³⁸ But for gaining, more frequent eating genuinely helps you get more food down when fullness is the limit.¹⁰ Aim for 4 to 6 eating occasions a day: think three meals plus a couple of shakes and a snack. That's the practical reason to eat often - not metabolism magic, just more chances to add calories.

Protein spread across the day

Split your daily protein across those meals - roughly 3 to 6 servings, each with a decent hit of protein. When your total protein is right, the exact spread doesn't change your results much,³⁷⁵³ so don't stress it. Just don't cram all your protein into one meal and skip it everywhere else.

The "anabolic window" is wide open

Forget the panic about slamming protein within 30 minutes of training. Your muscles stay sensitive to protein for up to 48 hours after a workout.³⁹⁴⁰ As long as you're eating enough protein across the day, there's no magic window to miss. Training somewhere between two normal meals covers it completely. The only time a quick post-workout shake actually helps is if you train first thing in the morning after a long overnight fast - and even then, it's minor.³⁹

This is the very top of the pyramid: the least important level, and the one the industry spends the most money convincing you is the most important. Here's the truth that saves you hundreds of dollars - almost no supplement does anything meaningful for building muscle. After decades of research, exactly one has strong, reliable evidence.⁴¹

The one that works: creatine monohydrate

Creatine is the single supplement with rock-solid evidence for muscle and strength - and it's cheap.⁴¹⁴² The facts, cutting through the myths:

• Dose: ~5 grams a day. That's it. No "loading" phase needed - a steady daily dose saturates your muscles in a few weeks.⁴²
• Timing doesn't matter - before, after, or nowhere near training. It works by saturating your muscles over time.⁴²
• It's safe - one of the most-studied supplements in existence, safe for healthy people of all ages, including teenagers. It does not damage your kidneys or cause hair loss - those are myths.⁴¹⁴²
• Vegetarians and vegans benefit more, since they start with lower natural creatine levels.⁴²
• Expect modest, real effects - a bit more strength and around a kilo of extra lean mass over time, plus a small early water-weight bump in the muscle.⁴¹

Everything else

Caffeine (~3–6 mg/kg before training) can genuinely help your workout performance, which indirectly helps you build.¹⁰ Protein powder counts too - but as we said in Section 3, that's a food that helps you hit protein and blend a shake, not a magic supplement. Beyond those, the popular muscle-building supplements - BCAAs, mass-gainer "anabolic" blends, test boosters - have been studied and don't deliver.¹⁰ Save your money and put it toward more actual food.

Food is the building material. Lifting is the signal that tells your body to use it. Without that signal, a surplus mostly turns into fat - so if you want the weight you gain to become muscle that fills your chest, you have to train. This isn't a full workout program (the pectus workout programs are that), but here's what actually matters, cut down to the parts a skinny beginner needs.

Why you can't skip this

A calorie surplus is permission to grow, not a command.²⁰ The command comes from lifting weights hard enough to challenge the muscle - that mechanical tension is the primary driver of muscle growth.³⁶⁵⁹ Eat in a surplus without training and you gain, but it's soft weight. Train hard and eat in a surplus and the same calories become muscle across your chest, shoulders, and back - exactly the tissue that makes a pectus dip look shallower.

The three rules that matter

• Progressive overload. Over time, do more - a little more weight, or a rep or two more, than last time. This steady increase in demand is what forces the muscle to grow; whether you add load or add reps, the progression is the point.⁵⁸ Write your lifts down so you can actually beat them.
• Enough volume. Muscle grows with the number of hard sets you do per muscle each week - more sets means more growth, up to a point.⁵⁶ As a beginner, roughly 10 or so hard sets per muscle group per week is plenty to grow on. You don't need marathon sessions.
• Enough frequency. Spreading that work across 2–4 sessions a week lets you train each muscle more than once and accumulate quality sets.⁵⁷ Full-body two or three times a week is ideal for a beginner.

Lift the big movements

You fill a frame fastest with compound lifts - movements that load a lot of muscle at once. Prioritise a press (push-up, bench, dip), a pull (row, pull-up), a hinge or squat for the legs, and an overhead press. For pectus specifically, movements that load the chest and serratus in a stretched position - like a dumbbell pullover or a deep push-up - directly target the muscle around the sternum. That's the exact logic the pectus workout programs are built on.

You're not just gaining weight - you're gaining it while working on your chest with a vacuum bell, a brace, training, or breathing work. Here's how the two fit together, because they reinforce each other more than most people realize.

Fuel makes the training work

The corrective and strengthening exercises in the pectus programs are the stimulus that tells your body to build muscle around the chest. But a stimulus with no building material builds nothing. The surplus and protein in this document are what let that training actually turn into visible muscle.²⁰³¹ Train hard, eat in a surplus, and the frame fills - do one without the other and you spin your wheels.

Weight and your structure

Remember the research from the "Why Pectus People Are Skinny" section: pectus patients were measurably under-developed in height and weight, and correction normalized it.² Getting to a healthy weight isn't cosmetic vanity - it's moving your body toward where it should have been. Filling out with muscle also changes how the dip reads to the eye long before any structural change finishes.

Muscle over fat - the pace rule

Because you want the new weight to be muscle that shapes your chest (not just fat), stick to the pace from Section 1 - roughly 0.5–1.5% of bodyweight a month for most people, faster only if you're a true beginner.¹⁰ Slow and steady, with your protein hit and your training consistent, is what puts muscle on the frame rather than softness over it.

A note for teens still growing

If you're a teenager, you're in the best window there is - your body is primed to grow, and good nutrition supports both height and the muscle you're adding.² Focus on eating enough quality food rather than aggressive bulking, keep protein up, and let your natural growth do a lot of the work. Loop a parent and your doctor in on any big changes.

Everything above becomes this: a simple, repeatable cycle you can start this week. The plan isn't a rigid menu - it's a set your number → track → adjust loop that works for any body, because it corrects itself as it goes.

Goal: find your real maintenance and starting target.

• Estimate maintenance (Section 2) and add your surplus - most skinny beginners start around +300–500 calories over maintenance.
• Hit that calorie number and your protein target (~0.7 g/lb) every single day.
• Weigh every morning; buy the blender; get your staples in the house.
• Don't judge progress yet - two weeks of water and food changes hide the real trend.

Goal: lock in steady gain at the right pace.

• Compare your weekly-average weight now vs week 2. Gaining ~0.25–0.5% of bodyweight a week? Perfect - hold it.
• Not gaining after 2 weeks? Add ~250 calories a day (easiest via one extra shake) and re-check.²¹
• Gaining too fast (over ~1% a week) with a soft belly? Trim ~200 calories a day.
• Keep training hard - the surplus only becomes muscle if the stimulus is there.²⁰

Goal: turn the plan into habits you don't have to think about.

• By now you know your foods and portions - you can loosen the strict tracking and eat by your learned routine.
• Keep the anchors: shake times locked, tinned fish and milk always stocked, eat by the clock.
• Re-assess maintenance - as you get heavier, you burn more, so your target creeps up. Keep nudging calories up to stay in a surplus.¹⁰
• At 12 weeks, take progress photos and measurements. Then run the loop again for the next block.

A sample gaining day

Here's what ~2,800 calories and ~150 g protein can look like for a low-appetite gainer - note how much comes from shakes and dense, low-effort food:

Two of the five "meals" are drinks. That's the low-appetite playbook in action - about 1,150 of these calories go down as liquid you barely have to work for.

Numbers are easier to copy than to explain, so let's run a real one. Meet a reader a lot like the people I coach: 24 years old, 185 cm (6'1"), 58 kg (128 lb) - tall, skinny, pectus, low appetite. His BMI is about 16.9, which is underweight. Here's exactly how he'd set his plan using the formulas from Sections 1 and 2. Swap in your own numbers as we go.

Step 1 - Maintenance

Quick estimate from Section 2: bodyweight in pounds × 10, then an activity factor. He weighs 128 lb and lifts three times a week but has a desk job, so ~1.5:¹⁰

Step 2 - Add the surplus

He's a skinny beginner, so he can gain toward the top of the range. Aiming for about half a pound a week, the surplus formula (weekly pounds × 500) gives ~250–350 extra calories a day. Round up a touch since he's a hard gainer:

Step 3 - Split the macros

Protein first (~1.6–2.2 g/kg), a fat floor he'll happily clear, then carbs fill the rest:³¹

Step 4 - Turn it into a day

2,300 calories and 120 g protein is a lot for a low appetite - so he leans on the low-appetite playbook. Two of his five "meals" are drinks:

Step 5 - Adjust

He hits ~2,300 every day and weighs each morning. After two weeks he compares his weekly-average weight. Up ~0.3 kg? Perfect - hold it. Flat? He adds ~250 calories a day (one bigger shake) and re-checks.²¹ That's the loop, and he'll run it for months. In a year of doing exactly this, a skinny beginner can add real, frame-filling size.

Gaining weight is a feedback loop: eat, measure, adjust. Skip the measuring and you're guessing - you'll either give up because "nothing's happening" (when it is) or coast in maintenance for months (when you think you're gaining). Here's how to actually see your progress.

The scale - weekly average, not daily

Weigh yourself every morning, same conditions (after the bathroom, before eating, minimal clothing), and take the weekly average. Daily weight bounces 1–2% from water, food, and salt alone - the average smooths that noise into a real signal.¹⁰ A single scary morning number means nothing; the trend across weeks is everything.

The adjust rule

Compare this week's average to two weeks ago. Gaining at your target pace (roughly 0.25–0.5% of bodyweight a week)? Hold everything. Flat for two weeks? You're not in a surplus - add ~250 calories a day and re-check.²¹ Gaining too fast with a softening belly? Trim ~200. That's the entire adjustment system. As you get heavier you burn more, so expect to keep nudging calories up over time.¹⁰

Photos and the tape don't lie

The scale can't tell muscle from fat, so back it up:

• Progress photos - front, side, back, once a month, same spot, same light, relaxed. Two months apart, the change you can't feel day to day becomes obvious.
• Tape measurements - chest, upper arms, thighs, and waist, monthly. Growing arms and chest with a stable waist is exactly the pattern you want: muscle, not fat.

You don't build muscle in the gym - you build it while you recover from the gym, and most of that recovery happens while you sleep. For a skinny guy trying to gain, cutting sleep quietly works against everything else you're doing.

Sleep drives the build

Sleep is when your body does most of its muscle repair and hormone work.⁶⁰ Short-change it and you pay twice. Even a single week of restricted sleep measurably lowers testosterone in healthy young men⁶¹ - the hormone you want high while building. And poor sleep disrupts appetite regulation,⁴⁶ which is the last thing a low-appetite gainer needs. Aim for 7–9 hours and treat it as part of the program, not an optional extra.

Rest is when growth happens

The same logic applies to training. You don't need to hammer the same muscle every day - muscle grows during the days between sessions, not during them. Train hard 2–4 times a week (Section 11), then let recovery and food do the building. More is not better here; enough, plus recovery is better.

Here's the truth nobody says out loud: the reason you're still skinny probably isn't that you don't know what to eat. It's that you've started and stopped a dozen times. Gaining weight with pectus is not an information problem - it's a consistency problem. So let's deal with it directly.

Why skinny guys quit

Three things break most people: nothing visibly changes in the first two weeks, the appetite keeps fighting, and underneath it all sits a quiet belief - "I'm just naturally skinny, this is who I am." That last one matters more than it looks. A chest you're unhappy with genuinely dents body image and quality of life - the research on pectus shows it clearly⁸⁹ - which makes it easy to give up and decide the body is fixed. It isn't. Your build responds to food and training like anyone else's; you just have to out-last the slow start.

Build habits, don't rely on motivation

Motivation is a feeling, and feelings come and go. Habits are what carry you on the days you don't feel it. Habits form through simple repetition over weeks - do the same thing at the same time and it slowly stops needing willpower.⁶² So engineer your environment so the right thing is the easy thing:

• Keep whole milk and tinned fish in the house always - never let "there's no food" be an excuse.
• Pre-portion your shake ingredients so making one is 60 seconds, not a decision.
• Eat by the clock, not by hunger (Section 7) - set meal and shake times and treat them like appointments.
• Track your weekly weight (Section 15) so you can see it working, which keeps you going.

Drop the "skinny" label

The most powerful shift is the quietest one: stop describing yourself as "the skinny guy who can't gain." You're a person currently running a gaining plan. Do it for yourself, on your own terms - motivation that comes from your own choice sticks far better than doing it to impress anyone else.⁶⁶ Give it three honest months before you judge whether it works. Almost everyone who quits, quits before the results were ever going to show.

This is the middle of the pyramid: food quality and micronutrients. Gaining weight is not an excuse to live on soda and candy. You can eat calorie-dense and still eat well - and you should, because you want to be a bigger, healthier version of yourself, not a puffier one.

Keep a whole-food base

Build most of your intake from real food - meat, fish, eggs, dairy, grains, fruit, vegetables, nuts - and use dense, less-healthy calories only to top up when you're short.¹⁰ A bit of ice cream or a pastry to hit your number is completely fine; a diet of only that is not. The dense-food tactics from Part 3 work just as well with quality food (olive oil, whole milk, nut butter, dried fruit) as with junk.

The fibre balancing act

Fibre - from vegetables, fruit, whole grains, and beans - is important for your health and digestion.⁶³ But there's a catch for you specifically: fibre is filling.⁶⁴ Loading up on huge volumes of raw vegetables and bran will fill your stomach before you hit your calories. So get enough fibre for your health, but don't overdo the super-high-fibre, low-calorie foods when you're struggling to eat enough. Cooked vegetables, fruit, and some whole grains cover your needs without crushing your appetite.

Water and the basics

Stay hydrated - it matters for health, digestion, and training.⁶⁵ But remember the trick from Part 3: don't fill up on plain water right before meals, and make some of your fluids count as calories (milk, juice, shakes) rather than drowning your appetite in water.²⁶ Get a bit of sunlight or a basic vitamin D, eat a variety of colours, and you've covered the micronutrient bases without overthinking it.

Almost everyone who fails to gain is making one of a handful of predictable mistakes. Here they are side by side with the fix - if the scale isn't moving, you're almost certainly on the left column somewhere.

Most skinny guys chasing this are young, and money is tight. Good news: gaining weight is one of the cheapest things you can do in fitness, because the foods that pack the most calories for the least fullness also happen to be the cheapest food on the shelf. You do not need expensive mass-gainers or fancy "clean" groceries - you need calories, and calories are cheap when you buy the right ones.

Think cost per calorie, not cost per item

A bag of oats looks more expensive than a single banana, but per calorie it's a fraction of the price. When you're gaining, the number that matters is how many calories a dollar buys you. Judge your shopping that way and your grocery bill barely moves even as you eat more.

The cheap dense-calorie staples

• Whole milk and milk powder - the classic skinny-guy tool. Milk powder blended into shakes is one of the cheapest ways on earth to add hundreds of calories and protein, and it barely fills you up.²⁶
• Oats, rice and pasta - pennies per serving, huge calories, cook a big batch and eat off it all week.
• Eggs and tinned fish - cheap protein and dense fats with zero cooking skill required.
• Peanut butter and cheap oils - the densest calories in the shop; a spoon of oil in your rice or a scoop of peanut butter in a shake adds calories you won't feel.
• Bananas, potatoes and frozen vegetables - dirt cheap, dense, and they keep.

When you start eating more than your stomach is used to, you'll feel it: bloated, uncomfortably full, sometimes a bit queasy. This is the number-one reason skinny guys quit in week one - not lack of willpower, just physical discomfort. The good news is it eases fast as your gut adapts, and a few simple moves make the whole thing far more comfortable.

Ramp up, don't jump

Your digestion adapts to how much you eat, but it needs a little time. Don't go from under-eating to a giant surplus overnight. Add your surplus gradually - a few hundred calories, hold for a week, add a bit more - and your stomach stretches to the new normal without the misery. This is the same slow, self-adjusting loop from the 12-week plan; comfort is just another reason to take it steady.

The comfort tactics

• Lean on liquids. Shakes are gentler on a full stomach than a big solid plate, and they empty faster, so they're your friend on the days solid food sits heavy.²⁶
• Go easy on huge raw-veg volumes. Fibre is filling and can bloat you when you pile it in - get enough for your health, but favour cooked vegetables and fruit over enormous raw salads and bran when you're trying to fit more food in.⁶³⁶⁴
• Spread it out. Four to six smaller meals sit far more comfortably than three enormous ones (Section 9).
• Time your drinks. Don't chug a litre of water right before a meal - hydrate between meals so you're not filling the tank with liquid you can't get calories from.⁶⁵

The evidence behind this program. The nutrition backbone is The Muscle and Strength Pyramid: Nutrition (Helms, Morgan & Valdez, 2025) and the primary research it draws on; the pectus-specific claims are drawn from the mrpectus research library. Where a source is a paywalled abstract, author, title, year and source are given so you can find the work.

1. Cheung SY-K. Exercise therapy in the correction of pectus excavatum. J Paediatr Respir Crit Care. 2005;1(2):10–13. - The pectus exercise foundation these programs build on.
2. Kim HK, Yoon JY, Han KN, Choi YH. Effect of the Nuss Procedure on the Physical Development of Patients with Pectus Excavatum. Ann Thorac Cardiovasc Surg. 2016;22(6):327–332. [studies/pectus-excavatum, PMID 27629820] - PE patients were measurably lighter and shorter than the normal population before treatment, normalizing after correction; under-development tracked with deformity severity.
3. Stagnaro N, et al. Cardiovascular MRI assessment of pectus excavatum in pediatric patients. [studies/pectus-excavatum, PMID 33256973] - Chest compression of the heart; a proposed mechanism for restricted development.
4. Pectus excavatum: not just a cosmetic problem. [studies/pectus-excavatum, PMID 32749790] - Functional and systemic effects beyond appearance.
5. Jaroszewski D, Notrica D, McMahon L, et al. Current management of pectus excavatum: a review and update of therapy and treatment recommendations. J Am Board Fam Med. 2010;23(2):230–239. - Prevalence and the asthenic body habitus associated with PE.
6. Haje SA, Haje DP. Orthopedic Approach to Pectus Deformities: 32 Years of Studies. Rev Bras Ortop. 2009;44(3):191–8. - Large clinical series on pectus growth and remodeling.
7. The pectus care guidelines: best practice consensus guidelines from the joint specialist societies. [studies/pectus-excavatum, PMID 38964837] - Consensus on assessment and management.
8. Body-image, self-concept and mental exposure in patients with pectus excavatum. mrpectus research library, PMID 21290134. - Measurable impact on body image and self-concept.
9. Pectus excavatum and pectus carinatum patients suffer from lower quality of life and impaired body image. mrpectus research library, PMID 21440452. - Lower QoL and more negative body image vs peers.
10. Helms ER, Morgan A, Valdez A. The Muscle and Strength Pyramid: Nutrition (3rd ed). 2025. - The evidence-based nutrition framework underlying this program: energy balance, macronutrient, timing and supplement hierarchy.
11. Hall KD, Farooqi IS, Friedman JM, et al. The energy balance model of obesity: beyond calories in, calories out. Am J Clin Nutr. 2022;115(5):1243–54. - Energy balance as the fundamental driver of body-weight change.
12. Cunningham JJ. A reanalysis of the factors influencing basal metabolic rate in normal adults. Am J Clin Nutr. 1980;33(11):2372–4. - Basis for maintenance-energy estimation.
13. Tinsley GM, Graybeal AJ, Moore ML. Resting metabolic rate in muscular physique athletes: validity of existing methods and development of new prediction equations. Appl Physiol Nutr Metab. 2019;44(4):397–406. - Maintenance estimation in trained individuals.
14. Pontzer H, Yamada Y, Sagayama H, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808–12. - Large-scale reference for human energy expenditure.
15. Wishnofsky M. Caloric equivalents of gained or lost weight. Am J Clin Nutr. 1958;6(5):542–6. - Origin of the ~3,500-calorie-per-pound guide.
16. Hall KD, Chow CC. Why is the 3500 kcal per pound weight loss rule wrong? Int J Obes. 2013;37(12):1614. - Why the rule is a rough guide, not an exact law.
17. Rozenek R, Ward P, Long S, Garhammer J. Effects of high-calorie supplements on body composition and muscular strength following resistance training. J Sports Med Phys Fitness. 2002;42(3):340–7. - Untrained men gained ~3 kg of near-pure lean mass on a high-calorie shake.
18. Smith RW, Harty PS, Stratton MT, et al. Predicting Adaptations to Resistance Training Plus Overfeeding Using Bayesian Regression. J Funct Morphol Kinesiol. 2021;6(2):36. - Gaining faster than ~2% body mass/month drove disproportionate fat gain.
19. Garthe I, Raastad T, Refsnes PE, Sundgot-Borgen J. Effect of nutritional intervention on body composition and performance in elite athletes. Eur J Sport Sci. 2013;13(3):295–303. - Faster weight gain added fat, not extra muscle or strength.
20. Helms ER, Spence AJ, Sousa C, et al. Effect of Small and Large Energy Surpluses on Strength, Muscle, and Skinfold Thickness in Resistance-Trained Individuals. Sports Med Open. 2023;9(1):102. - A larger surplus mostly added fat; surplus is permissive to gain, not a forcing function.
21. Slater GJ, Dieter BP, Marsh DJ, Helms ER, Shaw G, Iraki J. Is an Energy Surplus Required to Maximize Skeletal Muscle Hypertrophy Associated With Resistance Training? Front Nutr. 2019;6:131. - The surplus supports growth but training stimulus and protein drive it.
22. Levine JA, Eberhardt NL, Jensen MD. Role of Nonexercise Activity Thermogenesis in Resistance to Fat Gain in Humans. Science. 1999;283(5399):212–4. - Overfeeding produced 10-fold differences in fat gain via non-exercise activity - the "hard gainer" mechanism.
23. Pontzer H, Durazo-Arvizu R, Dugas LR, et al. Constrained Total Energy Expenditure and Metabolic Adaptation to Physical Activity in Adult Humans. Curr Biol. 2016;26(3):410–7. - The body adapts expenditure to activity, complicating simple calorie math.
24. Barakat C, Pearson J, Escalante G, Campbell B, De Souza EO. Body recomposition: can trained individuals build muscle and lose fat at the same time? Strength Cond J. 2020;42(5):7–21. - Muscle gain and fat loss can co-occur, especially in less-trained people.
25. Gallagher D, Heymsfield SB, Heo M, et al. Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index. Am J Clin Nutr. 2000;72(3):694–701. - Body-fat and BMI reference ranges.
26. Abe T, Buckner SL, Dankel SJ, et al. Skeletal muscle mass in human athletes: what is the upper limit? Am J Hum Biol. 2018;30(3):e23102. - Muscular athletes often carry higher body fat, yet still build muscle well.
27. DellaValle DM, Roe LS, Rolls BJ. Does the consumption of caloric and non-caloric beverages with a meal affect energy intake? Appetite. 2005;44(2):187–93. - Liquid calories are poorly compensated for and add to total intake.
28. Mattes RD. Fluid calories and energy balance: the good, the bad, and the uncertain. Physiol Behav. 2006;89(1):66–70. - Beverages produce weaker satiety than solid food.
29. Cassady BA, Considine RV, Mattes RD. Beverage consumption, appetite, and energy intake. Am J Clin Nutr. 2012;95(3):587–93. - Drinks blunt appetite signalling less than solids.
30. DiMeglio DP, Mattes RD. Liquid versus solid carbohydrate: effects on food intake and body weight. Int J Obes. 2000;24(6):794–800. - Liquid carbohydrate led to greater net intake than solid.
31. Rolls BJ, Bell EA, Thorwart ML. Water incorporated into a food but not served with a food decreases energy intake in lean women. Am J Clin Nutr. 1999;70(4):448–55. - Fullness is driven by food volume - the energy-density principle.
32. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength. Br J Sports Med. 2018;52(6):376–384. - Muscle gains plateau at ~1.6 g protein/kg/day.
33. Nunes EA, Colenso-Semple L, McKellar SR, et al. Systematic review and meta-analysis of protein intake to support muscle mass and function. J Cachexia Sarcopenia Muscle. 2022;13(2):795–810. - Confirms the ~1.6 g/kg protein guideline for muscle.
34. Roberts BM, Helms ER, Trexler ET, Fitschen PJ. Nutritional Recommendations for Physique Athletes. J Hum Kinet. 2020;71:79–108. - Practical macro and calorie recommendations.
35. Iraki J, Fitschen P, Espinar S, Helms E. Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports. 2019;7(7):154. - Evidence-based guidance for the muscle-gaining phase.
36. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. - Foundational macro and supplement recommendations.
37. Schoenfeld BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res. 2010;24(10):2857–2872. - How muscle actually grows.
38. Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr. 2018;15:10. - Protein distribution across meals.
39. Kerksick CM, Arent S, Schoenfeld BJ, et al. International Society of Sports Nutrition position stand: nutrient timing. J Int Soc Sports Nutr. 2017;14:33. - Meal frequency and timing have small effects vs total intake.
40. Aragon AA, Schoenfeld BJ. Nutrient timing revisited: is there a post-exercise anabolic window? J Int Soc Sports Nutr. 2013;10(1):5. - The post-workout "window" is far wider than once believed.
41. Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013;10(1):53. - Total protein matters more than exact timing.
42. Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation. J Int Soc Sports Nutr. 2017;14:18. - Creatine's strong evidence base and safety across ages.
43. Antonio J, Candow DG, Forbes SC, et al. Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show? J Int Soc Sports Nutr. 2021;18(1):13. - Debunks creatine myths; ~5 g/day, no loading needed, timing irrelevant.
44. Geyer H, Parr MK, Mareck U, et al. Analysis of non-hormonal nutritional supplements for anabolic-androgenic steroids - results of an international study. Int J Sports Med. 2004;25(2):124–9. - A meaningful share of supplements contained unlabelled banned substances.
45. Cohen PA. Hazards of hindsight - monitoring the safety of nutritional supplements. N Engl J Med. 2014;370(14):1277–80. - Supplement industry is lightly regulated; contamination and mislabelling are common.
46. Outram S, Stewart B. Doping through supplement use: a review of the available empirical data and of the corresponding ethical issues. Int J Sport Nutr Exerc Metab. 2015;25(1):54–9. - Contaminated supplements as a route to inadvertent doping; third-party testing as mitigation.
47. Smith GI, Atherton P, Reeds DN, et al. Dietary omega-3 fatty acid supplementation increases the rate of muscle protein synthesis in older adults. Am J Clin Nutr. 2011;93(2):402–12. - Omega-3 fats (as in sardines) support the muscle protein response.
48. Wolff J. Das Gesetz der Transformation der Knochen (The Law of Bone Remodeling). Berlin: Hirschwald; 1892. - Bone adapts its structure to mechanical load - the basis for pairing nutrition with corrective training.
49. Frost HM. Bone's mechanostat: a 2003 update. Anat Rec A Discov Mol Cell Evol Biol. 2003;275(2):1081–1101. - The strain-threshold model of bone adaptation.
50. Phillips SM, Van Loon LJC. Dietary protein for athletes: from requirements to optimum adaptation. J Sports Sci. 2011;29 Suppl 1:S29–38. - Protein needs and quality for training adaptation.
51. Trommelen J, van Loon LJC. Pre-sleep protein ingestion to improve the skeletal muscle adaptive response to exercise training. Nutrients. 2016;8(12):763. - Protein before sleep as a useful extra meal for building.
52. Snijders T, Res PT, Smeets JS, et al. Protein ingestion before sleep increases muscle mass and strength gains during resistance-type exercise training in healthy young men. J Nutr. 2015;145(6):1178–84. - Direct evidence for the bedtime protein shake.
53. Areta JL, Burke LM, Ross ML, et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol. 2013;591(9):2319–31. - Supports spreading protein across several daily meals.
54. Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435–41. - Sleep influences appetite regulation and body composition.
55. Kerksick CM, Wilborn CD, Roberts MD, et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15(1):38. - Broad evidence-based review underpinning these recommendations.
56. Schoenfeld BJ, Ogborn D, Krieger JW. Dose-response relationship between weekly resistance training volume and increases in muscle mass: a systematic review and meta-analysis. J Sports Sci. 2017;35(11):1073–1082. - More weekly hard sets per muscle means more growth, up to a point.
57. Schoenfeld BJ, Ogborn D, Krieger JW. Effects of resistance training frequency on measures of muscle hypertrophy: a systematic review and meta-analysis. Sports Med. 2016;46(11):1689–1697. - Training a muscle across 2+ sessions a week helps accumulate quality volume.
58. Plotkin D, Coleman M, Van Every D, et al. Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations. PeerJ. 2022;10:e14142. - Progression drives growth whether you add load or add reps.
59. Currier BS, Mcleod JC, Banfield L, et al. Resistance training prescription for muscle strength and hypertrophy in healthy adults: a systematic review and network meta-analysis. Br J Sports Med. 2023;57(18):1211–1220. - Evidence-based guidance on how to structure training for growth.
60. Dattilo M, Antunes HKM, Medeiros A, et al. Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Med Hypotheses. 2011;77(2):220–222. - Sleep is central to muscle repair and recovery.
61. Leproult R, Van Cauter E. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA. 2011;305(21):2173–2174. - One week of short sleep measurably lowered testosterone.
62. Lally P, van Jaarsveld CHM, Potts HWW, Wardle J. How are habits formed: modelling habit formation in the real world. Eur J Soc Psychol. 2010;40(6):998–1009. - Habits form through repetition over weeks - the basis for eating on a schedule.
63. Slavin JL. Dietary fiber and body weight. Nutrition. 2005;21(3):411–418. - Fibre's role in health and its filling effect on the diet.
64. Clark MJ, Slavin JL. The effect of fiber on satiety and food intake: a systematic review. J Am Coll Nutr. 2013;32(3):200–211. - Fibre increases fullness - useful for dieters, a hurdle for low-appetite gainers.
65. Popkin BM, D'Anci KE, Rosenberg IH. Water, hydration, and health. Nutr Rev. 2010;68(8):439–458. - Hydration and its role in health and function.
66. Deci EL, Ryan RM. Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. Am Psychol. 2000;55(1):68–78. - Motivation that comes from your own choice sustains behaviour change.

© mrpectus · The Pectus Nutrition Program v1.0 · Mihail Veleski · For education, not medical advice.