High protein diets: how much protein do you really need?

Why does your body need protein?

Protein is one of the main nutrients in food, alongside carbohydrates and fat. The British Nutrition Foundation explains that we need protein for growth, repair and maintenance of our bodies, especially our bones and muscles, and that it can also provide energy.

How much protein do you need each day?

The British Nutrition Foundation says adults need about 0.75g of protein for every kilogram of body weight each day. For someone who weighs 70kg, that is around 52g a day. Needs are a little higher during pregnancy, and people who do vigorous training may need more, as may some older adults.

Most people already get plenty. The British Nutrition Foundation says that, on average, men in the UK eat about 85g of protein a day and women about 67g, which is more than most adults need.

To give you an idea of how much protein is in everyday foods, the British Nutrition Foundation says 100g of grilled chicken breast contains around 32g, 100g of boiled egg around 14g, which is about 7g in a medium egg, 100g of boiled red lentils around 8g, and 100g of semi-skimmed milk around 3.5g, so a 150ml glass gives you about 5g.

Can you eat too much protein?

Eating more protein than you need does not automatically build more muscle or make you healthier. An NHS dietitian at Mersey Care NHS Foundation Trust warns that excessive amounts can put extra stress on the kidneys and liver, increase the risk of dehydration and kidney stones, and lead to weight gain.

Very high protein diets can also crowd out other foods, such as fruit, vegetables and wholegrains, that give you fibre, vitamins and minerals. If you have a kidney condition, speak to your GP or kidney team before increasing your protein intake.

Is plant protein as good as animal protein?

You can get all the protein you need from plants. The British Nutrition Foundation says protein from a variety of plant foods, eaten during the day, supplies enough of the essential building blocks of protein, called amino acids, that your body needs. Beans, lentils, chickpeas, tofu, soya, quinoa, nuts and seeds are all good sources, and they come with fibre too. For more on plant-based eating, read is a vegan diet healthy?

Are high protein products worth buying?

Many products are now labelled "high protein", from bars and yoghurts to cereals and crisps. Some can be useful, but they often cost more than everyday protein foods and are more processed. Foods such as eggs, beans, lentils, yoghurt, milk, fish and lean meat usually give you good nutrition for less money. Check the nutrition label and ingredients list before you buy.

Do you need protein supplements?

Most people do not. The Mersey Care dietitian says that unless you are a competitive elite athlete, you are unlikely to benefit from protein products, and suggests spreading protein through the day as part of normal meals. If you are not sure whether you are getting enough protein, for example because you find it hard to eat enough, speak to your GP or a registered dietitian.