To gain weight healthily, eat about 300 to 500 calories a day more than you burn and do strength training at least twice a week, so more of the new weight is muscle. A good pace is 0.25 to 0.5% of your body weight a week, which is about 0.4 to 0.75 lb (0.17 to 0.34 kg) for someone who weighs 150 lb.
Eating far more than that does not build muscle faster. It mostly adds fat, as one study in elite athletes showed (more on it below).
Key takeaways
- Surplus: 300 to 500 extra calories a day (NHS), or about 10 to 20% above maintenance.
- Pace: 0.25 to 0.5% of body weight a week. 10 lb takes about 13 to 27 weeks at 150 lb.
- Protein: about 1.6 g per kg (0.7 g per lb) a day. Past that, extra protein did not add muscle in trials.
- Training: lift at least 2 days a week, adding weight or reps over time.
- Food: nut butters, nuts, oils, whole milk, yogurt, oats, rice and dried fruit add calories without junk food.
Are you underweight?
The CDC classes an adult BMI under 18.5 as underweight. BMI is only a screening number, so a lean, muscular person can sit near the line and be healthy, and someone with a "normal" BMI may still want to build muscle.
Talk to a doctor first if you have lost weight without trying, lost weight suddenly, or use control of food to cope with your feelings. The NHS lists all three as reasons to get checked, because unexplained weight loss can be a sign of an underlying condition.
How many calories do you need to gain weight?
- Find your maintenance calories. The TDEE calculator gives an estimate from your age, height, weight and activity. A week of honest tracking with a stable weight is even better.
- Add a modest surplus. The NHS suggests adults add around 300 to 500 calories a day. A 2019 review of off-season bodybuilders recommends a surplus of about 10 to 20%.
- Check after 2 to 3 weeks. If your weekly average weight has not moved, add another 100 to 200 calories. If it climbs faster than the pace below, pull back by the same amount.
| Maintenance (kcal/day) | +10% surplus | +20% surplus | Daily target range (kcal) |
|---|---|---|---|
| 2,000 | 200 | 400 | 2,200 to 2,400 |
| 2,400 | 240 | 480 | 2,640 to 2,880 |
| 2,800 | 280 | 560 | 3,080 to 3,360 |
| 3,200 | 320 | 640 | 3,520 to 3,840 |
The weight gain calculator does this math for your goal. If you want full menus, see the 2,500-calorie meal plan or the 3,000-calorie meal prep guide.
How fast should you gain weight?
The same bodybuilding review suggests gaining about 0.25 to 0.5% of body weight a week for beginners and intermediates, and less for advanced lifters, who build muscle more slowly.
| Body weight | 0.25% per week | 0.5% per week |
|---|---|---|
| 120 lb (54 kg) | 0.3 lb (0.14 kg) | 0.6 lb (0.27 kg) |
| 150 lb (68 kg) | 0.4 lb (0.17 kg) | 0.75 lb (0.34 kg) |
| 180 lb (82 kg) | 0.45 lb (0.20 kg) | 0.9 lb (0.41 kg) |
Going faster mainly adds fat. In a randomized study of 39 elite athletes doing four strength sessions a week for 8 to 12 weeks, one group followed a meal plan in surplus (about 3,585 calories a day) and the other ate as they liked (about 2,964). The meal-plan group gained more weight, 3.9% vs 1.5% of body weight, and fat mass rose 15% vs 3%. Lean mass gains were not different between the groups.
How much protein do you need to gain weight?
A 2018 meta-analysis of 49 trials with 1,863 people found that, with resistance training, protein intakes above about 1.6 g per kg of body weight a day gave no further gain in muscle mass. The Dietary Guidelines for Americans 2025-2030 give a general target of 1.2 to 1.6 g/kg.
| Body weight | Protein at 1.6 g/kg (g/day) | Per meal, 4 meals (g) |
|---|---|---|
| 120 lb (54 kg) | 87 | 22 |
| 150 lb (68 kg) | 109 | 27 |
| 180 lb (82 kg) | 131 | 33 |
Spreading it over three to five meals is easier than forcing it into one or two. Shakes help when appetite is the bottleneck; protein shake calories compares common options.
Healthy calorie-dense foods for weight gain
These foods add calories in a small volume, which matters when you already feel full. Values from USDA FoodData Central.
| Food | Portion | Calories | Protein (g) |
|---|---|---|---|
| Granola, homemade | 1/2 cup (61 g) | 298 | 8.3 |
| Salmon, farmed, cooked | 5 oz (142 g) | 293 | 31.4 |
| Brown rice, cooked | 1 cup (202 g) | 248 | 5.5 |
| Greek yogurt, plain, whole milk | 1 cup (227 g) | 220 | 20.4 |
| Peanut butter | 2 tbsp (32 g) | 191 | 7.1 |
| Walnuts | 1 oz (28 g) | 185 | 4.3 |
| Almonds | 1 oz (28 g) | 164 | 6.0 |
| Avocado | 1/2 fruit (100 g) | 160 | 2.0 |
| Eggs, hard-boiled | 2 large (100 g) | 155 | 12.6 |
| Rolled oats, dry | 1/2 cup (40.5 g) | 153 | 5.3 |
| Whole milk | 1 cup (244 g) | 149 | 7.7 |
| Medjool dates | 2 dates (48 g) | 133 | 0.9 |
| Olive oil | 1 tbsp (13.5 g) | 119 | 0 |
| Cheddar cheese | 1 oz (28 g) | 114 | 6.5 |
| Raisins | 1/4 cup (36 g) | 108 | 1.2 |
Nuts are among the most efficient options per bite; every nut ranked by calories and protein has the full list. The NHS advises against relying on chocolate, cakes and sugary drinks to gain weight: they add calories without the protein, fiber and micronutrients you need.
Easy ways to add 500 calories a day
You rarely need a new meal. Small additions to food you already eat get you there:
- A blender shake: 1 cup whole milk, 2 tbsp peanut butter, 1 banana and 1/2 cup oats is 598 calories and 21 g protein.
- A tablespoon of olive oil on rice, pasta or vegetables: 119 calories.
- A handful of almonds (1 oz) between meals: 164 calories.
- Whole-milk Greek yogurt with granola (1 cup plus 1/4 cup): about 369 calories and 25 g protein.
- A bigger scoop of rice or oats: an extra cup of cooked brown rice is 248 calories.
Two tips from the NHS for small appetites: eat more often, with snacks between meals, and do not fill up on drinks right before you eat.
Strength training for weight gain
The Physical Activity Guidelines for Americans recommend muscle-strengthening activity on at least 2 days a week. When gaining, 2 to 4 sessions a week is a practical range.
- Train the big movements: squats or leg presses, deadlifts or hip hinges, presses and rows.
- Add load or reps over time. Progress is the signal for muscle to grow. Log your lifts so you know you are moving forward.
- Keep some cardio. It supports heart health and appetite. Just count it in your calorie target.
How to track weight gain
Weigh yourself at the same time each morning and watch the 7-day average, not single days. Daily weight can swing with salt, carbs and digestion. A waist measurement every two weeks helps you tell muscle from fat: if your weight rises but your waist grows quickly too, trim the surplus.
Logging food matters as much as it does for weight loss, because most people who "eat a lot" and cannot gain are eating less than they think. Our list of the best apps to help you gain weight compares trackers. Nutrify logs a meal from a photo, so a quick snap of your shake or snack keeps the count honest.
Why you can't gain weight
- Your real intake is lower than it feels. One big dinner does not make up for a skipped breakfast and lunch. Track for a week.
- Your activity is higher than you think. Long walks, a physical job or sport raise maintenance. Recalculate if your routine changes.
- Small appetite. Use liquid calories and calorie-dense add-ons, and eat on a schedule rather than waiting for hunger.
- You are gaining, then stopping. As you get heavier, maintenance rises too. Add 100 to 200 calories when the average stalls for two to three weeks.
- Unexplained weight loss. If you are losing weight without trying, talk to your doctor before changing your diet.
Sources
- NHS, Advice for underweight adults (300 to 500 extra calories, eating pattern, when to see a GP).
- CDC, Adult BMI categories.
- Iraki J, et al. Nutrition recommendations for bodybuilders in the off-season: a narrative review. Sports, 2019.
- Garthe I, et al. Effect of nutritional intervention on body composition and performance in elite athletes. Eur J Sport Sci, 2013.
- Morton RW, et al. Protein supplementation and resistance training-induced gains in muscle mass and strength: a systematic review and meta-analysis. Br J Sports Med, 2018.
- Dietary Guidelines for Americans, 2025-2030 (protein 1.2 to 1.6 g/kg).
- U.S. Department of Health and Human Services, Physical Activity Guidelines for Americans: top 10 things to know.
- USDA FoodData Central: granola 171646, farmed salmon, cooked 175168, brown rice, cooked 169704, Greek yogurt, whole milk 171304, peanut butter 172470, walnuts 170187, almonds 170567, avocado 171705, hard-boiled egg 173424, oats, dry 173904, whole milk 171265, Medjool dates 168191, olive oil 171413, cheddar 173414, raisins 168165, banana 173944.
