The Skinny Guy's Guide to Gaining Weight
Eat "heaps" but still can't put on weight? You're not cursed with a fast metabolism, you're just not eating enough yet. Here's how to finally gain, and make sure it's muscle, not just fat.
Find out how much you really need to eat
The free Fit Gorillas Macro Calculator works out your maintenance and bulking calories, plus your protein, carbs and fats, in 30 seconds.
Why skinny guys struggle to gain
Calling yourself a "hardgainer" usually comes down to a few things:
- You eat less than you think. One big dinner feels like a lot, but a skipped breakfast and a light lunch cancel it out. Most skinny guys are eating close to maintenance without realising.
- You move a lot. Many lean guys fidget, walk, play sport or have active jobs, which burns more calories than they expect.
- You have a small appetite. You feel full quickly, so big meals are hard work.
- You're inconsistent. Eating well 3 days a week isn't enough. Your weekly average is what counts.
The good news: all of these can be fixed with a plan. Your body has no choice but to grow when you consistently eat more than you burn.
Step 1: Eat more than you burn
Work out your maintenance calories (TDEE), then add 300–500 calories a day. Skinny guys can use the bigger end of this range, because gaining is your hardest part.
Example: 25-year-old guy, 65 kg, 180 cm, trains 3–5 days a week
- Maintenance: about 2,570 calories a day
- Bulking target: 2,570 + 300–500 = about 2,870–3,070 calories a day
- Target gain: about 0.3 kg a week (roughly 1–1.5 kg a month)
If the scales don't move after 2–3 weeks, add another 100–200 calories a day. More detail in how many calories you need to build muscle.
Step 2: Make eating easier
You don't need to force down giant plates of chicken and broccoli. You need foods that pack lots of calories into a small amount of food.
| Food | Serving | Calories (approx.) |
|---|---|---|
| Oats (dry) | 80 g | 300 |
| Peanut butter | 2 tbsp (32 g) | 190 |
| Mixed nuts | 30 g handful | 180 |
| Whole milk | 250 ml | 160 |
| Cooked rice | 1 cup | 240 |
| Cheese | 30 g | 120 |
| Olive oil | 1 tbsp | 120 |
| Avocado | ½ medium | 120 |
| Raisins / dried fruit | 40 g | 120 |
Tricks that make a big difference
- Drink your calories. Liquid calories don't fill you up like food. A homemade gainer shake can add 600+ calories in a couple of minutes.
- Eat 4–5 times a day instead of 3. Smaller, more frequent meals are easier than three huge ones.
- Add, don't replace. Cook in a little olive oil, add cheese, drink milk instead of water with meals, and put peanut butter on toast.
- Don't fill up on salad and veg first. Have some, but eat your protein and carbs first.
- Plan your day ahead so you know you'll hit your number before the day even starts.
The Gorilla gainer shake (~610 calories, ~42 g protein)
300 ml whole milk + 1 scoop whey protein + 1 banana + 2 tbsp peanut butter. Blend and drink. Add 40 g of oats for about 150 extra calories.
Step 3: Get enough protein
Calories make you gain weight. Protein, along with training, makes sure more of that weight is muscle. Eat at least 1.6 g of protein per kg of body weight. More is fine. For a 65 kg guy that's at least 105 g a day. See how much protein you need to build muscle.
A sample 3,000-calorie day
| Meal | What to eat | Calories | Protein |
|---|---|---|---|
| Breakfast | 80 g oats with 300 ml whole milk and a banana | ~600 | ~22 g |
| Mid-morning | Gorilla gainer shake | ~610 | ~42 g |
| Lunch | 150 g chicken breast, 200 g cooked rice, veg, 1 tbsp olive oil | ~660 | ~52 g |
| Dinner | 150 g lean beef mince, 100 g pasta (dry weight) with sauce, 20 g cheese | ~800 | ~56 g |
| Evening | 200 g Greek yoghurt + 30 g nuts | ~380 | ~24 g |
| Total | ~3,050 | ~195 g |
Swap in foods you like. What matters is hitting your calories and protein every day.
Step 4: Train so it turns into muscle
Eating more without lifting just adds fat. Training tells your body to use those extra calories to build muscle.
- Lift 3–4 times a week. A full-body or upper/lower program works well for beginners.
- Focus on big lifts: squats, deadlifts or Romanian deadlifts, bench press, overhead press, rows and pull-ups.
- Add weight or reps over time. This is called progressive overload, and it's the main thing that makes muscles grow.
- Keep cardio modest. Some is fine for health, but lots of running burns calories you're working hard to eat.
- Sleep 7–9 hours. That's when you recover and grow.
Step 5: Track it and adjust
- Track your food for at least 2–3 weeks. It's the fastest way to find out what you're really eating.
- Weigh in 3–7 mornings a week and use the weekly average.
- Every 2–3 weeks: not gaining? Add 100–200 calories a day. Gaining faster than about 0.5% a week? Take 100–200 off.
The Fit Gorillas Macro Tracker makes this easy: plan your day in grams, see your calories against your target, and get weekly check-ins that tell you when to add more food.
5 skinny guy mistakes
- Guessing instead of tracking. "I eat heaps" is the number one reason skinny guys stay skinny.
- Skipping meals when busy. One missed meal can wipe out your surplus for the day. Keep shakes or snacks on hand.
- Living on junk food. It's fine in small amounts, but a "dirty bulk" adds fat fast and leaves you short on protein.
- Program hopping. Stick with one solid program for at least 8–12 weeks and focus on getting stronger.
- Panicking about a bit of fat. Some fat gain is normal when you bulk. Keep the gain slow and steady and it stays small.
Quick FAQ
I have a fast metabolism. Can I still gain weight?
Yes. Some people do burn more calories than others, mostly through moving more. It just means your number is higher. Once you eat above it consistently, you'll gain.
Do I need mass gainer shakes?
No. Mass gainers are just convenient calories. A homemade shake with milk, oats, banana, peanut butter and protein powder does the same job and is usually cheaper.
How long until I see results?
If you gain about 0.5% of your body weight a week and train consistently, most guys notice a real difference in the mirror and in their strength within 2–3 months.
Stop guessing. Start growing.
Two steps to finally put on size.
Macro Calculator
Get your maintenance and bulking calories, plus your protein, carbs and fats.
Calculate my calories →Macro Tracker
Plan your day in grams and see your calories and macros against your targets instantly. Includes 147 USDA-sourced foods and weekly check-ins that tell you when to eat more.
Get the Macro Tracker →Want the full training and eating plan too? See the Muscle-Building Gorilla Guide
Not Born. It's Built.
This article is general information for healthy adults and isn't medical advice. If you're underweight because of a medical condition or have trouble eating, talk to your doctor. Maintenance estimates use the Mifflin-St Jeor equation with a 1.55 activity multiplier; food values are approximate, so check the labels on your own brands. Related reading: What are macros? · How much protein do you need? · How many calories to build muscle? · How to cut without losing muscle