High-protein diet while dieting
Eating more protein during a calorie deficit helps keep lean mass and gives a small extra fat loss compared with a standard-protein diet of the same calories. The effect is modest but consistent, and it pairs well with resistance training.
What the science says
- Higher protein preserves lean mass and adds a little fat loss Strong evidence
Wycherley et al.'s 2012 meta-analysis of 24 trials (1,063 adults, about 12 weeks) found that high-protein, low-fat diets, compared with standard-protein diets of the same calories, led to about 0.8 kg more weight loss, 0.9 kg more fat loss, 0.4 kg less fat-free mass loss and a smaller drop in resting energy expenditure.
- With hard training, higher protein can even add lean mass Moderate evidence
Longland et al. (2016) put 40 young men on a roughly 40% calorie deficit for 4 weeks with resistance training and intervals 6 days a week. The 2.4 g/kg/day group gained 1.2 kg lean mass and lost 4.8 kg fat, vs 0.1 kg and 3.5 kg on 1.2 g/kg/day.
- Lean, trained people need the most Moderate evidence
Helms et al.'s 2014 systematic review of 6 studies in resistance-trained, lean athletes concluded that protein needs during a deficit are likely 2.3–3.1 g per kg of fat-free mass, rising with the size of the deficit and leanness.
- Protein helps with fullness Limited evidence
In Wycherley et al.'s meta-analysis, greater satiety on the high-protein diet was reported in only 3 of the 5 studies that measured it.
How to apply it
Set protein first, spread it over the day, and fill the rest of your calories with the carbohydrate and fat you prefer.
Who should be careful
High protein intakes are well tolerated by healthy adults. People with kidney disease must not raise protein without medical advice. Anyone with diabetes, high blood pressure or another obesity-related condition, a history of eating disorders, who is pregnant or breastfeeding, or who is considering weight-loss medication should plan weight loss with a physician or registered dietitian; this page gives no drug advice.
Frequently asked questions
How much protein should I eat while dieting?
About 1.6–2.4 g per kg of body weight a day, toward the top if you are lean, training hard and in a large deficit. If you carry a lot of fat, use your goal weight.
Does high protein make you lose more fat?
A little. Wycherley et al.'s meta-analysis found about 0.9 kg more fat loss over roughly 12 weeks, plus better preservation of fat-free mass.
Can I gain muscle while losing fat with high protein?
In Longland et al.'s trial, young men training 6 days a week on 2.4 g/kg/day gained 1.2 kg lean mass during a 4-week deficit. That was a hard, supervised program, so expect smaller effects in everyday life.
Scientific references
- Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials
- Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial
- A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes
More on weight loss
- Calorie deficit Strong evidence
Fat loss requires eating fewer calories than you burn for weeks to months; every diet that works does this, whatever it is called.
- Rate of weight loss Moderate evidence
For people who lift, losing about 0.
- Resistance training while dieting Strong evidence
Lifting weights during a diet makes much more of the weight you lose come from fat instead of muscle, and it keeps or raises strength.
- Cardio for weight loss Moderate evidence
Cardio helps fat loss, but at typical doses it produces only a couple of kilograms on its own; clinically meaningful loss takes high volumes (more than about 250 minutes a week) or a calorie deficit alongside it.
- Diet breaks and refeeds Moderate evidence
Planned periods at maintenance calories in the middle of a diet are at least as effective as dieting continuously and may make the diet easier to tolerate.
- Intermittent fasting Moderate evidence
Intermittent fasting (5:2, alternate-day fasting or time-restricted eating) works for weight loss about as well as an ordinary calorie-controlled diet, but not better.