Muscle & weight-gain guide
Calorie surplus: how to gain weight & build muscle
Last updated: July 10, 2026
Short answer: a calorie surplus means eating more calories than you burn. Add 250-500 above maintenance, eat 1.6-2.2 g protein per kg, and train with weights — that combination builds muscle with minimal fat. Find your maintenance number with the TDEE calculator, then add your surplus.
If a calorie deficit is how you lose fat, a calorie surplus is how you do the opposite: gain weight and build muscle. The trick is gaining the rightweight — muscle, not just fat — which comes down to three levers: the size of the surplus, protein, and training.
How calories build muscle
Muscle is built when resistance training signals your body to grow, protein supplies the raw material, and a surplus supplies the extra energy to do it. Remove any one and progress slows: train without enough calories or protein and you stall; eat a big surplus without training and you just add fat. All three together is what turns extra calories into muscle.
How big should the surplus be?
| Daily surplus | Weekly gain | Best for |
|---|---|---|
| 250 kcal | ~0.5 lb (0.25 kg) | Lean bulk — most muscle, least fat |
| 500 kcal | ~1 lb (0.45 kg) | Faster gain, some extra fat; hard gainers |
| 750+ kcal | 1.5+ lb | Rarely worth it — mostly fat, not more muscle |
Muscle can only be built so fast — natural lifters might gain 0.5-2 lb of muscle per month at best, faster for beginners. A giant surplus can't outrun that limit, so anything above ~500 mostly becomes fat you'll have to diet off later. Slower and leaner wins.
Protein: the non-negotiable
Aim for 1.6-2.2 g of protein per kg of body weight (about 0.7-1 g per lb), spread across the day. Protein is the raw material for muscle and the most filling macro, so it also keeps a bulk from turning into unnecessary fat gain. Dial in your grams with themacro calculator and see the energy in each macro in ourcalories in protein, carbs & fat guide.
Gaining weight when you're underweight
If you're trying to gain weight for health reasons, the same surplus applies but focus onenergy-dense, nutritious foods — nuts, nut butters, olive oil, dairy, oats, rice, and fatty fish — so you can hit the calories without feeling overly full. Liquid calories (milk, smoothies) help "hard gainers" who struggle to eat enough. If you're unintentionally losing weight or underweight, check with a doctor first.
Track your surplus
Just like cutting, bulking works best when you can actually see your intake. TheMyPlate app calculates your gaining target and logs meals by photo or barcode, so you know you're hitting the surplus and the protein — not guessing. Start with your number from the free calorie calculator.
Frequently asked questions
What is a calorie surplus?
A calorie surplus means eating more calories than your body burns each day. The extra energy has to go somewhere — it is stored, as a mix of muscle and fat. Combined with resistance training and enough protein, a surplus is how you gain muscle and body weight. Without training, a surplus mostly adds fat.
How many calories do I need to gain weight?
Add roughly 250-500 calories above your maintenance (TDEE) each day. A 500/day surplus adds about 1 lb (0.45 kg) per week. If you are underweight or a "hard gainer," you may need more; if you gain fat quickly, stay near 250-300. Find your maintenance first with the TDEE calculator, then add your surplus on top.
How many calories to build muscle?
For lean muscle gain, a modest surplus of 250-500 calories above maintenance is ideal — enough to fuel growth without adding much fat. Pair it with 1.6-2.2 g of protein per kg of body weight and progressive resistance training. Much larger surpluses do not build muscle faster; they mostly add fat, because muscle can only be built so quickly.
Do you need a calorie surplus to build muscle?
For most people, yes — building new muscle tissue requires extra energy and protein, so a surplus makes it faster and more efficient. The exceptions are beginners, people returning after a break, and those with higher body fat, who can often build some muscle while losing fat ("body recomposition") at maintenance. But for steady, ongoing muscle gain, a slight surplus is the reliable path.
How much protein do I need to build muscle?
Research points to about 1.6-2.2 grams of protein per kilogram of body weight (roughly 0.7-1 gram per pound) per day to maximize muscle growth. Spreading it across 3-4 meals of 20-40 g each helps. Protein is also the most filling macro, which helps you avoid unnecessary fat gain during a bulk. See our guide to calories in protein, carbs and fat.
How do I gain weight without getting fat?
Keep the surplus modest (250-500 kcal), prioritize protein, train with progressive overload so the extra energy builds muscle, and get most calories from nutrient-dense whole foods rather than junk. Track your weekly weight trend and adjust: if you are gaining more than ~0.5-1% of body weight per week, trim the surplus. This is often called a "lean bulk" or "clean bulk."