What the research says about eating to build muscle, for lifters who want a simple plan without constant tracking.
Muscle-building diet advice boils down to how much to eat, how much protein, and when. The research gives fairly clear answers.
The short version
- You need a surplus. The International Society of Sports Nutrition says gaining lean mass requires a sustained calorie surplus along with resistance training, and that diets from low-fat to ketogenic can work about equally well.
- Protein has a ceiling. A meta-analysis of 49 studies found extra protein stopped adding muscle gains beyond about 1.62 g per kg of body weight a day.
- Timing matters far less than the total. A meta-analysis of 23 muscle-size studies found total protein intake was the strongest predictor of muscle growth, and timing showed no significant effect once other factors were controlled.
Calories: eat more, but not wildly more
A surplus is the one non-negotiable. Start a little above maintenance, watch the scale and your lifts over a few weeks, and adjust.
Key takeaway: Muscle needs a surplus, but a bigger surplus is not automatically better.
Protein: aim for the plateau
About 1.6 g per kg a day (roughly 0.7 g per pound) is where the benefit levels off for most people. That’s an average across studies, and the same analysis found the benefit shrank with age. If you’re older, our piece on protein needs after 40 goes further.
An 80 kg lifter lands near 130 g a day, which you can split across your regular meals.
Timing: stop sweating the 30-minute rule
The idea that you must eat within an hour of training is a long-standing gym belief. A review of post-exercise nutrient timing found the significance, and even the existence, of a short post-workout window is in question, and the meta-analysis above agrees. Hit your daily number first. Eating protein around training is fine, just not urgent.
Hunger and sticking with it
Higher-protein meals do make you feel a bit fuller. A review of acute feeding trials found a modest satiety effect, though no clear drop in what people ate at the next meal. That review looked at weight loss, not muscle gain, but its point carries over: benefits showed up in people who actually followed the plan. The best diet is usually the one you can repeat.
Putting it into practice
- Work out your protein target (about 1.6 g/kg).
- Build each meal around a protein food: eggs, fish, chicken, dairy, tofu, lentils.
- Add a modest surplus with carbs and fats, and check progress every few weeks.
Proteinly is built around a protein-first approach with no calorie counting, and its automatic eating timer reminds you to eat every 2 hours. It’s a consistency tool that makes regular meals a habit, and it doesn’t do anything special to your muscles.
FAQ
Do I have to count calories?
Not necessarily. The research says a surplus matters, and it doesn’t say you have to log every meal. Weekly weight and gym progress can guide you.
Next steps
Pick your protein target, spread it across the day, and keep a modest surplus. If you want help building the habit, visit Proteinly, learn about our approach, and follow us on YouTube.
Related: A Daily Protein Plan for Lean Muscle.