How much protein do you actually need when you are eating less?

Disclaimer: This article is general information, not medical advice. If you have a health condition, talk to your GP or pharmacist before making a big change to how you eat.

When you eat less, your body does not only give up fat. Some of what you lose is lean tissue: muscle, and the strength that comes with it. That matters more than it sounds. Muscle is what gets you off a low chair, up a flight of stairs and through a shopping trip, and muscle lost in your forties and fifties is slow to win back.

Two things protect it. One is eating enough protein. The other is giving your muscles a reason to stay, which is strength training. This guide covers the first.

The number

The UK reference intake for protein is 0.75 grams per kilogram of body weight a day. That figure is a floor for avoiding deficiency in the general population, not a target for someone actively losing weight. Evidence: strong

When you are in an energy deficit, most guidance lands between 1.2 and 1.6 grams per kilogram of body weight a day, and people training regularly sit nearer 1.4 to 2.0. Roughly double the baseline, in other words. The reason is simple: when total food goes down, protein has to hold its ground rather than shrink with everything else. Evidence: moderate to strong

One honest caveat at higher body weights. Taking 1.4 g/kg literally at 130 kg gives 182 g of protein a day, which is neither realistic nor necessary. Dietitians usually calculate from a healthy or adjusted body weight instead. If you are unsure what your own number should be, that is a good question for a dietitian or your GP. Evidence: moderate

Spread it across the day

Your body builds muscle protein meal by meal, not from a daily total. The research points to 20 to 40 grams of good quality protein per meal, every three to four waking hours. People over 40 do better at the top of that range, because older muscle responds less to smaller amounts. Evidence: moderate to strong

For a sense of scale:

• a chicken breast is around 30 g
• a 200 g pot of Greek yoghurt is around 20 g
• two eggs are around 12 g
• a standard whey shake is 20 to 25 g
• a tin of tuna is around 25 g
• 150 g of cooked lentils is around 13 g

Three meals at 30 g gets most people to 90 g, which is enough for someone around 60 kg but short for someone at 90 kg. That gap is usually where a fourth protein-containing meal or a shake earns its place.

When your appetite is smaller than your target

This is the real difficulty. Hitting a higher protein target on less food takes deliberate effort, and people routinely fall short without noticing. What helps, roughly in order of usefulness: Evidence: moderate for the approach, weaker for individual tactics

• Protein first. Eat the protein part of the meal before the rest, so that fullness arrives after the chicken rather than instead of it.
• Drink some of it. On days when solid food does not appeal, milk, Greek yoghurt drinks and protein shakes go down when a plate will not.
• Small and often. Four modest protein-containing meals beat two large ones you cannot finish.
• Keep it easy. Tinned fish, pre-cooked chicken, cottage cheese, eggs and frozen edamame remove the cooking step on the days you have no appetite for cooking.

Protein alone is only half of it

Protein gives your body the raw material. Strength training gives it the reason to use that material on muscle rather than burning it. In studies of people losing weight, the two together preserve substantially more lean tissue than either on its own. Doing one without the other leaves most of the benefit on the table. Evidence: strong

Talk to your GP or pharmacist if: you have kidney disease and are considering a higher protein intake; you are losing weight much faster than about 1% of your body weight a week over several weeks; you cannot keep food down; or you are unsure what protein target fits your body and your health.

The short version

Aim for 1.2 to 1.6 grams of protein per kilogram a day, in 20 to 40 gram amounts across three to five meals, and pair it with two or three short strength sessions a week. That combination is the difference between losing weight and losing your strength along with it.

Sources

• International Society of Sports Nutrition position stand: protein and exercise, JISSN, 2017
• International Society of Sports Nutrition position stand: diets and body composition, JISSN, 2017
• Murphy and Koehler, energy deficit and lean mass during resistance training, Scand J Med Sci Sports, 2021
• NHS, protein as part of a balanced diet
• British Nutrition Foundation, protein requirements