Protein for weight loss: how much you need to lose fat and keep muscle

What the trials show

The strongest summary comes from Wycherley and colleagues, who pooled 24 randomised trials comparing higher-protein and standard-protein diets with the same calories and fat. Over an average of about 12 weeks, the higher-protein diets produced:

• About 0.8 kilograms more weight loss and 0.9 kilograms more fat loss.
• About 0.4 kilograms more lean mass preserved.
• A smaller drop in resting energy expenditure, by about 140 kilocalories a day.
• Greater satiety in three of the five studies that measured it.

These are modest differences over a few months. They are real, and they all point in the same direction: more of the weight you lose is fat.

How much protein during a deficit

The calculator on this page gives three figures for your weight, drawn from the ISSN position stand: the minimum of 0.8 grams per kilogram for a sedentary adult, the range of 1.4 to 2.0 grams for people who train, and about 0.25 grams per kilogram per meal.

The review led by Leidy, focused on weight management, points to 1.2 to 1.6 grams per kilogram a day. For an illustrative person of 80 kilograms, that is about 96 to 128 grams a day; if they lift weights regularly, the ISSN range of 112 to 160 grams applies.

The everyday guide to protein needs explains the difference between the minimum and the training range in more detail.

When you train hard in a deficit

One trial shows how far the effect can go in a specific setting. Longland and colleagues put 40 young men on a diet about 40% below their needs for four weeks, with resistance training and high-intensity intervals six days a week. The group eating 2.4 grams of protein per kilogram gained about 1.2 kilograms of lean mass and lost 4.8 kilograms of fat. The group on 1.2 grams gained almost no lean mass, 0.1 kilogram, and lost 3.5 kilograms of fat.

That is a striking result, but it comes from young men in a short, intense and closely controlled study. It does not mean that everyone should eat 2.4 grams per kilogram. It does show that when the deficit is large and training is hard, protein matters more. For most people, the ISSN range combined with two or three strength sessions a week is the sensible target; see strength training for executives.

Protein and appetite: a modest help

Protein is often presented as the key to not feeling hungry. Leidy's review is more measured. Acute feeding studies show a modest satiety effect, with greater feelings of fullness and higher satiety hormones after higher-protein meals, but no clear reduction in what people eat at the next meal.

The review also notes that long-term results were limited and conflicting, largely because many people did not stick to the prescribed diet. Those who did benefited; those who did not saw little change. The lesson: choose a way of eating protein that you enjoy and can keep, rather than an extreme plan you will abandon.

Spreading it across the day

Leidy's review suggests at least 25 to 30 grams of protein per meal, and the ISSN recommends a dose every three to four hours. In practice, that means three meals of similar protein content rather than most of it at dinner.

• Breakfast is usually the weakest meal: eggs, yoghurt, skyr or cottage cheese change it quickly.
• Lunch and dinner: build the plate around fish, poultry, eggs, lean meat, tofu or a generous portion of pulses, then add vegetables and starch.
• Snacks, if you need them: a dairy product or a handful of nuts rather than biscuits.

The NHS Eatwell Guide places beans, pulses, fish, eggs and meat in the same food group, describes pulses as good, low-fat alternatives to meat that also bring fibre, and recommends at least two portions of fish a week, one of them oily. The Mediterranean diet offers a pattern that combines all of this naturally.

Keeping it in proportion

Protein supports a weight-loss plan; it does not replace one. The overall deficit, set as described in calorie deficit, still decides how much weight you lose. Protein, with strength training, decides how much of it is fat. If progress stalls despite both, the reasons are explored in weight loss plateau.

If you have kidney disease, liver disease or diabetes treated with medication, or if you are pregnant, ask your doctor or a registered dietitian before raising your protein intake. Supplements are a convenience, not a necessity; food can cover your needs.

Pair protein with training, on Never Skip Club

Protein protects muscle only if muscle is asked to work. Create your free account on Never Skip Club, launch guided strength sessions built in a minute for the body area, level and equipment you choose, and join a crew of friends who keep the same weekly rhythm, with a ranking that rewards regularity. If you want a professional to align your training with your nutrition, find a coach from our network, or sign in to book a session.