The Protein Guide How Much You Need and Where to Find It

Protein is a family of large molecules built from smaller units called amino acids. The body uses it to build and repair muscle, skin, bone and hair, to make enzymes and hormones, and to support the immune system. Unlike carbohydrate and fat, the body does not store protein in a dedicated reserve, so it needs a regular supply.

Of the twenty amino acids, nine are called essential because the body cannot make them, and they must come from food. Foods differ in how much of each essential amino acid they supply. Animal foods such as meat, fish, eggs and dairy typically provide all nine in useful amounts. Most plant foods are lower in one or more, although soya and quinoa are notable exceptions, and a varied plant-based diet can supply everything needed.

Protein has particular importance for people who train, because muscle repair and growth depend on it. It also matters at the other end of life: as we age, we tend to lose muscle, and adequate protein combined with strength training is one of the best defences. Protein is also more filling than carbohydrate or fat, which can help with managing appetite.

The question that most people ask about protein is how much to eat, and the answer depends on who you are and what you do.

The UK Reference Nutrient Intake for adults is 0.75 grams of protein per kilogram of body weight per day, which is around 56 grams for an average man and 45 grams for an average woman. This is designed to meet the needs of almost everyone who is not very active, and most British adults already eat more than this.

For people who train regularly, particularly those doing resistance exercise, position statements from sports nutrition organisations commonly suggest around 1.2 to 2.0 grams per kilogram of body weight per day. For older adults, some expert groups suggest around 1.0 to 1.2 grams per kilogram, because the ageing body responds less efficiently to protein. There is no strong evidence that going far above this range brings added muscle benefit.

Is a high-protein diet safe? In healthy people, studies have not shown that higher intakes within this range harm the kidneys. People with existing kidney disease are the important exception and need medical guidance. As always, it is better to meet your needs through a balanced diet than to treat protein as the only priority.

It is easy to underestimate how much protein is in ordinary food, and to overestimate how much is in some marketed products. Knowing the approximate values of common foods allows you to plan without weighing everything.

The figures below are approximate, and vary by brand and preparation. A medium egg provides roughly 6 to 7 grams. Around 100 grams of cooked chicken breast supplies about 30 grams, and a similar amount of canned tuna or cooked salmon provides around 20 to 25 grams. A 150-gram pot of Greek-style yoghurt has around 12 to 15 grams, and 100 grams of cottage cheese about 11 grams. A glass of milk, around 200 millilitres, offers about 7 grams.

Among plant foods, 100 grams of cooked lentils provides around 9 grams, cooked chickpeas and kidney beans around 8 to 9 grams, and firm tofu approximately 10 to 15 grams. A handful of nuts, around 30 grams, supplies about 5 to 7 grams, and a tablespoon of peanut butter about 4 grams. Bread, oats, pasta and rice offer smaller but useful amounts that add up across a day.

More people are eating less meat, whether for health, ethical or environmental reasons. Plant-based diets can provide enough protein, and many people live well on them, but they ask for slightly more thought.

Good plant sources include beans, lentils, chickpeas, peas, tofu, tempeh, soya milk and yoghurt, edamame, nuts, seeds, quinoa and wholegrains. Soya is a particularly useful food because it provides all the essential amino acids. Other plant proteins tend to be low in one essential amino acid, but the shortfall is easily made up by eating a variety of foods across the day, such as beans with rice or bread, or hummus with wholegrain pitta. They do not need to be combined in the same meal.

Because plant proteins are generally a little less digestible, and because plant foods contain fewer of some amino acids, people following vegan diets may want to aim for the upper end of the recommended range, around 1.2 to 1.6 grams per kilogram if they train regularly. Eating a good mix of soya, pulses and grains helps.

Sports nutrition marketing suggests that precise timing of protein, and the right powder, are essential. The research says something more modest.

Total daily protein intake matters most. There is some evidence that spreading protein across the day, with roughly 20 to 40 grams in each of three or four meals, may be slightly better for building muscle than eating most of it in one meal. The so-called anabolic window after a workout is wider than once claimed, so there is no need to rush to a shake. A meal containing protein within a couple of hours of training works well.

Protein powders, bars and shakes are convenient but not necessary. Whey protein is quickly digested and rich in the amino acid leucine, which plays a role in stimulating muscle building. Casein is slower to digest, and soya, pea and blended plant powders offer alternatives. A powder can be useful if your appetite is small, if you are vegetarian and finding it hard to reach your target, or if you are short of time, but they are no better than food.

Knowing the numbers is of little value unless they can be turned into a manageable pattern of eating. The aim is to arrive at a way of eating that provides enough protein without effort.

Start by estimating your target using the weight-based figures in this ebook. Then record what you eat for a few days. Most people find that breakfast is low in protein, and that dinner carries most of the load. Moving some protein to the morning, with eggs, yoghurt or a bean-based dish, balances the day. Keep protein-rich staples in the house, such as tinned fish, eggs, yoghurt, lentils, tofu and frozen fish or chicken, so that a good meal is always possible.

Common mistakes include relying heavily on bars and shakes, neglecting vegetables and fibre in the pursuit of protein, and assuming that more is always better. Variety matters, since different protein foods bring other nutrients with them, such as iron, calcium, zinc and omega-3 fats. Focus on whole foods first.

Eat enough overall, too. If your energy intake is too low, the body may use protein as fuel rather than for repair, and training adaptations suffer.