How much protein do you need a day? A guide for active adults

How much protein should I eat? It is one of the questions I am asked most often. Most adults who train regularly need more protein than the minimum set for the general population, with daily targets of about 1.4 to 2.0 g per kilogram of body weight for most exercising adults and higher protein intakes during periods of muscle gain or fat loss [1,3]. In this article I explain how much protein active adults need, how to spread it across the day, and how needs change with age, using a food first approach.

More than the minimum

The standard recommended dietary allowance of 0.8 g of protein per kilogram of body weight per day for adults is intended only to prevent deficiency [1,8], and active adults need more whether they focus on endurance or resistance training [1,3]. Protein intakes of at least 1.2 to 1.6 g per kilogram per day are a more suitable target for health in adults [8], and about 1.4 to 2.0 g per kilogram per day is sufficient for most people who exercise, supporting muscle repair and remodelling in endurance training as well as gains in muscle mass and strength when combined with resistance training [1,3,4]. For a 70 kg adult, that range works out at roughly 100 to 140 g a day. During resistance training, gains in muscle mass appear to level off at around 1.6 g per kilogram per day on average, although some people may benefit from up to about 2.2 g [3], and when you are eating less to lose body fat, higher protein intakes of about 2.3 to 3.1 g per kilogram per day may help resistance trained people to keep lean mass [1]. A common misconception is that eating more protein harms the kidneys or weakens bones, but in healthy people there is no evidence that higher protein intakes harm kidney function or bone health [1,8].

Building protein into the day

Spread it out. Rather than eating most of your protein in one large meal, aim for meals or snacks that each provide roughly 0.25 to 0.4 g per kilogram of body weight, which is about 20 to 40 g for most adults, at intervals of three to four hours [1,2]. At about 0.4 g per kilogram per meal, reaching 1.6 g per kilogram per day takes at least four meals [2].

Around training. The effect of exercise on muscle lasts for at least 24 hours, although it diminishes with time [1], so protein at every meal counts, not only the meal after a session.

Protein quality. Proteins are made of building blocks called amino acids, and nine of these are essential amino acids that must come from food, including leucine, which plays a key role in triggering muscle building [1,9]. Animal foods such as milk, eggs, meat and fish contain all nine essential amino acids, including enough leucine, in the proportions muscle needs [1,9]. Most single plant foods contain lower amounts of one or more essential amino acids, including leucine, although soy protein is an exception and supports gains in strength and muscle mass with resistance training to a similar degree to animal protein [9,10]. People who follow a plant based diet can get all of the essential amino acids by combining different plant sources across the day, such as beans or lentils with rice, oats or grains, and by eating a little more protein in total [9,11].

How protein needs change with age

Under 65. In adults under 65 who undertake resistance training, protein intakes of 1.6 g per kilogram per day or more are associated with greater gains in lean mass [3,4].

Over 65. Older adults need more protein than younger adults, partly because muscle responds less strongly to the protein in each meal, a change known as anabolic resistance [5,6]. At least 1.0 to 1.2 g per kilogram per day is recommended for healthy older people, rising to at least 1.2 g per kilogram per day for those who exercise or are otherwise active [5,6]. In adults over 65 who undertake resistance training, protein intakes of 1.2 to 1.6 g per kilogram per day are associated with greater gains in lean mass [4].

Do you need protein powder?

Most active adults can meet their protein needs through whole food sources of protein, and protein supplements are a safe and convenient way to add high quality protein when that is difficult [1], for example when you are busy or travelling [7]. Some products contain other ingredients that increase the risk of contamination, so athletes in tested sport should choose carefully [7].

Protein in practice

The following steps provide a simple framework for most healthy active adults.

• Work out your range. Multiply your body weight in kilograms by 1.4 and by 2.0, or by at least 1.2 if you are over 65 and active [1,5].
• Plan your meals. Include about 20 to 40 g of protein at each main meal [1,2], for example eggs on toast, porridge made with milk, chicken, fish, tofu or lentils.
• Add a protein snack. A snack between meals helps you to eat protein every three to four hours [1], for example a glass of milk, a yoghurt, or cheese and crackers.
• Mix your sources. If you follow a plant based diet, combine different plant foods across the day so you get all of the essential amino acids, and eat a little more protein in total [9,11].
• Use powder if it helps. A shake is a convenient option when food is not practical [1,7].

Protein works best within a diet that also provides enough energy and carbohydrate for training [1]. Anyone with a medical condition, particularly kidney disease, should take medical advice before increasing their protein intake [1,5].

Summing up

Most active adults do well on about 1.4 to 2.0 g of protein per kilogram of body weight per day [1], spread across meals of about 20 to 40 g [1,2]. Older adults need more protein than younger adults, and it works best alongside resistance training [4,5,6]. Protein supports the adaptations to both endurance and resistance training [1,3,4], and protein from whole food options can meet most people’s needs [1].

This article gives general information about exercise and nutrition and is not a substitute for individual advice from your GP, a registered dietitian, a physiotherapist or another qualified healthcare professional. If you have a health condition, an injury or symptoms, have recently been unwell or had an operation, or are pregnant or have recently given birth, speak to a healthcare professional before making changes. Stop and seek advice if you feel pain or become unwell while exercising.