Proteine: The Complete Evidence-Based Guide

Proteine, or protein, is the macronutrient people worry about most and understand least. It builds and repairs the body, supports muscle, and keeps you feeling full, yet the marketing around powders and shakes muddies the water. This evidence-based guide covers what proteine actually does, how much you really need, and where to get it without overthinking it.

What is proteine

Proteine is one of the three main macronutrients, alongside carbohydrate and fat. It is made from smaller units called amino acids, often described as the building blocks of the body. Of the twenty amino acids humans use, nine are essential, meaning your body cannot make them and you must get them from food.

Your body uses these amino acids to build and repair muscle, make enzymes and hormones, and support the immune system. Proteine also supplies energy at roughly four calories per gram, though that is not its main job. It is one piece of a wider picture we explore in our full guide to protein and in our overview of nutrition.

Why your body needs it

Unlike fat, the body has no large store of protein to draw on, which is why a steady daily intake matters. If you fall short over time, the body starts breaking down muscle to meet essential needs, which is why adequate proteine is especially important during weight loss, illness recovery and ageing.

Beyond muscle, proteine plays quieter but vital roles: transporting nutrients, clotting blood, and forming the structure of skin, hair and nails. It is not just for gym-goers. Everyone needs enough, and most healthy people in developed countries already get a reasonable amount from a varied diet.

How much you need

General guidance sets a baseline of around 0.75g to 0.8g of proteine per kilogram of body weight a day for most adults. That prevents deficiency but is a floor rather than a target. Active people, older adults and those losing weight while protecting muscle often benefit from more.

These are general ranges, not personalised prescriptions. Needs vary with health, activity and age, so use them as a starting point. Spreading intake across meals, rather than loading it all into dinner, tends to support fullness and muscle maintenance better.

Best proteine sources

Whole foods should provide most of your proteine, because they bring other nutrients along with the amino acids. Animal foods such as meat, fish, eggs and dairy contain all nine essential amino acids, while most single plant foods are lower in one or more.

• Animal sources: chicken breast around 30g per 100g, eggs about 6g each, Greek yoghurt roughly 10g per 100g, and fish that also provides healthy fats.
• Plant sources: lentils and chickpeas around 8g per half cup cooked, tofu about 8g per 100g, plus nuts and seeds in smaller amounts.

The old idea that plant eaters must combine proteins at every meal is outdated: a varied diet across the day covers all essential amino acids easily. For portions and practical ideas, see our lists of high protein foods and everyday protein foods, and note that a well-planned vegetarian diet can meet needs comfortably.

Proteine and weight management

Proteine is the most filling macronutrient, so higher-protein meals tend to curb appetite and make a calorie target easier to hold. It also has a slightly higher thermic effect, meaning the body uses a little more energy to digest it. During weight loss, enough proteine helps preserve muscle so more of the loss comes from fat.

None of this makes proteine a magic fat-burner. Weight change still comes down to overall energy balance, covered in our high protein diet for weight loss guide. Proteine simply makes a sensible plan easier to stick to.

Powders and supplements

Protein powder is convenient, not essential. It is a concentrated food source that can help you hit a target when whole foods are impractical, such as after training or on a busy day. Whey is popular and well absorbed, while soya, pea and other blends work well for plant-based eaters.

If you choose one, look for independent third-party testing such as Informed Sport or NSF Certified for Sport, which verify what is on the label. A basic protein powder and a simple shaker bottle cover most needs, with prices ranging from budget tubs to premium isolates. Our reviews of the best protein powder and protein shakes go into detail.

Common proteine myths

A few persistent claims are worth correcting so you can ignore the noise.

• More is always better: beyond your needs, extra proteine is simply used for energy, not turned into extra muscle on its own.
• Proteine harms healthy kidneys: in people with healthy kidneys, higher intakes have not been shown to cause harm, though those with kidney disease need medical guidance.
• You must eat straight after training: the "anabolic window" is overstated; total daily intake matters far more than precise timing.

Authorities including the Harvard Nutrition Source and the Academy of Nutrition and Dietetics stress the quality and variety of proteine sources over sheer quantity. For supplement specifics, the NIH Office of Dietary Supplements is a reliable reference, and everyday food advice is well covered by the NHS.