How much protein do you really need?

Every cell in your body contains protein. But what is protein, which foods contain it, how much do you need each day… and why?

Dr Lindy Alexander
February 2018

If you’ve gone down the health food section of your supermarket lately, you may have noticed the large range of protein products and powders on offer. Claiming to promote everything from more energy to weight loss and bigger muscles, protein seems to be the must-have for health. But is the hype justified?

What is protein?

Protein is an essential nutrient in our diet. It plays an important role in muscle growth and repair as well contributing to enzyme and hormone production.

“The building blocks of proteins are called amino acids, and they’re chemically linked to each other to form various combinations of proteins,” says Tim McMaster, accredited practising dietitian and spokesperson for the Dietitians Association of Australia.

“There are 20 different types of amino acids and they’re broken up into 2 main categories – those that can be made by the human body (non-essential amino acids) and those that must be provided through the diet (essential amino acids).”

Why do we need protein?

Every cell in the human body contains protein and it makes up about half of our dry body weight. The protein we eat is broken down and helps to maintain muscle mass and metabolism.

A severe lack of protein can affect almost every part of the body’s function and lead to muscle wastage and a poor immune system.

How much protein do you really need?

Protein requirements change as you age, and they differ depending on body weight and gender, but McMasters says that protein should ideally make up 15­–25% of your total energy intake. The government’s guidelines recommend the following daily intake for people aged 19­–70:

  • Men: 0.84g per kilogram of body weight per day. For example, if a man weighs 85kg, his recommended intake is approximately 71g.
  • Women: 0.75g per kilogram of body weight per day. For example, if a woman weighs 70kg, her recommended intake is approximately 52g.

For those aged over 70, the recommended daily intake is 81g a day (or 1.07g per kg of body weight) for men and 57g a day (or 0.94g per kg of body weight) for women.

Pregnant women need more protein in the second and third trimesters; their protein requirements go up to 1g per kilogram of body weight per day.

The best sources of protein

McMaster says that animal products such as meat, chicken, fish, eggs and dairy contain all the essential amino acids your body needs. Plant-based proteins like grains, legumes, pulses and soy products are also good sources of many of the essential amino acids. 

For example, Healthline outlines how much protein you’ll find in these sources:

  • 85g of cooked lean beef: 22g protein
  • 85g salmon: 19g protein
  • ½ cup raw oats: 13 grams
  • 1 cup of full fat milk: 8g protein
  • 1 cup quinoa: 8g protein
  • 1 egg: 6g protein
  • 28g almonds (about ¼ cup): 6g protein
  • 1 cup chopped broccoli: 3g protein

Do I need to supplement protein?

“Protein deficiencies in Australia aren’t common, but may occur in people with special requirements, such as those going through cancer treatment,” says McMaster.

“Individuals following vegetarian or vegan diets must make sure that they eat a wide range of plant proteins together every day. This is to ensure they get all of the essential amino acids on a regular basis.”

While protein shakes can seem like a quick and easy option, it’s just as effective and often cheaper to get the same amount of protein through everyday foods.

The recommended serving sizes of protein shakes usually contain more protein than you’re likely to need in one go, given you’re probably going to be getting other sources in your diet.

“So you get no additional benefit except running out of protein powder faster and spending more money on expensive supplements,” says McMaster.

A very high protein diet could be dangerous, with potential risks of reduced heart function, reduced metabolism, mild dehydration, osteoporosis and bowel disorders.

And protein shakes aren’t usually a healthy choice; they often contain preservatives, and artificial sweeteners such as aspartame and saccharin. If you’re going to have the occasional protein shake, look for one that is low in sugar and refined grains, preferably made with pea or hempseed protein powder.

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