How much protein do you need?
Protein is essential for the repair of muscles and tissues, muscle growth, and regulation of metabolism.
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The amount of protein that you need depends on your body weight ( see How to calculate your daily protein needs) and your health.
When you are sick or under stress, your body needs more protein as it uses energy to fight off what ails you. Your immune system depends on a constant supply of amino acids - the building blocks of protein. If you do not take in enough calories and proteins, you risk malnutrition and muscle wasting.
During pregnancy, the recommended daily amount (RDA) increases by 6g per day, and by 11g per day when breast-feeding. Children need more protein than adults for growth: about 2.2g of protein per 1kg (2 ¼ lb) of body weight every day in the first six months of life, and 2g per 1kg (2 ¼ lb) for the next six months. A child's RDA then gradually decreases throughout childhood and adolescence, until age 18 when it becomes 0.75g per 1kg (2 ¼ lb) per day.
The protein needs for athletes vary according to body weight and the type of activity (see Very active people need more protein). Most athletes eat more protein than they need, believing it will help increase their muscle mass. But protein consumed in excess is either used as energy when carbohydrate and calorie intake is low or converted to fat.
Most people in the West eat far more protein than they need; deficiency is very rare. Some diets suggest eating extra protein to aid weight loss. Excess protein, however, has been linked with osteoporosis and kidney disease, and with calcium stones in the kidneys.
How to calculate your daily protein needs
The recommended daily amount (RDA) for dietary protein is calculated on ideal body weight (the average weight for your height and gender).
Every day, adults need to eat 0.75g of protein per 1kg (2 ¼ lb) of body weight. Therefore, a man who weighs 82kg (180lb) needs to consume about 61g of protein per day; and a woman who weighs 68kg (150lb) needs an intake of about 51g of protein each day.
However, growing children and adolescents and pregnant women require an increased amount of protein in their diet (see How much protein do you need?).
Lisa Hark, PhD RD & Dr Darwin Deen
Nutrition for Life Copyright © 2005 Dorling Kindersley Text copyright © 2005 Lisa Hark and Darwin Deen
Posted 14.02.2011
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