Work out how much to eat to build muscle while keeping fat gain low.
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How it works
- Your maintenance calories are estimated with the Mifflin-St Jeor equation and an activity factor.
- A small surplus is added: about 10–20% for beginners and intermediates, and less for advanced lifters.
- Protein is set at 1.6–2.2 g per kg of body weight, with the rest of your calories from fat and carbohydrate.
Evidence-based targets
| Recommendation | |
|---|---|
| Calorie surplus | About 10–20% above maintenance; advanced lifters at the lower end |
| Weight gain | About 0.25–0.5% of body weight a week for novice and intermediate lifters |
| Protein | 1.6–2.2 g per kg of body weight a day |
| Fat | 0.5–1.5 g per kg of body weight a day |
These come from a review of nutrition for natural bodybuilders in the off-season. Track your weekly average weight and adjust by 100–150 kcal a day if you’re off target.
Frequently asked questions
What is a lean bulk?
Eating slightly more than you burn, alongside resistance training, to build muscle while keeping fat gain small.
How fast should I gain weight?
About 0.25–0.5% of your body weight a week if you’re a beginner or intermediate; slower if you’re advanced.
Is anything stored?
No, it runs in your browser.
Sources
- Iraki et al. (2019): Nutrition recommendations for bodybuilders in the off-season
- UK Chief Medical Officers’ physical activity guidelines
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