How much protein do you really need?
The so-called protein revolution has seen this macronutrient given top billing in human nutrition. So what is protein, which foods contain it, and can you have too much of a good thing?
If you’ve been studying the packaging at your supermarket lately, you may have noticed the large range of protein-packed, high protein and your daily protein intake products on offer. One recent study awarded protein health 'halo status', finding it to be closely associated with weight management, energy levels, immune health and an overall healthy life. But is the hype justified?
What is protein?
Protein – from the Greek protos, meaning 'first' – is an essential nutrient in our diet. It plays a key role in muscle growth and repair, as well contributing to enzyme and hormone production. Protein is one of the three major macronutrients, alongside carbohydrates and fat.
“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 two 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 severely lacking protein intake can affect almost every part of the body’s function and lead to muscle wasting and a poor immune system.
How much protein do you really need?
Protein intake requirements change as you age, and they differ depending on body weight and gender, but Tim says that protein should ideally make up 15-25% of your total energy intake. Dietitians Australia recommend the following daily protein 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 people aged over 70, the recommended daily intake is 1g per kg of body weight.
Pregnant women need more protein in their second and third trimesters, to ensure optimum growth of baby’s tissues and organs, including the brain. Protein requirements go up to 1g per kilogram of body weight per day.
What are the best sources of protein?
Tim says that animal products contain all the essential amino acids your body needs. This includes red meat, chicken, fish, dairy and eggs (egg whites are almost pure protein). Plant-based proteins such as 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 cooked lean beef: 22g protein
- 85g salmon: 19g protein
- ½ cup raw oats: 13g
- 1 cup 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
It may be easier to get your daily intake than you think. For example, if your requirement for protein is about 52g a day, you would get even more than that with milk and oats for breakfast, two eggs for lunch and fish for dinner.
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 Tim.
“Individuals following vegetarian or vegan diets must make sure that they eat a wide range of plant proteins (see what about plant-based proteins paragraph below) 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 natural 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 Tim.
A very high protein intake could be dangerous, with potential risks of reduced heart function, reduced metabolism, mild dehydration, osteoporosis and bowel disorders.
And protein shakes aren’t always 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 hemp seed protein powder.
Can you lose weight on a high-protein diet?
If you remember the 1970s, you’ll remember the Scarsdale diet. Created by Dr Herman Tarnower, a cardiologist from Scarsdale New York, it was a 14-day high-protein, low-calorie, low-carb weight-loss plan. Other high-protein intake weight-loss programs followed, including the Atkins, South Beach and all things keto.
While the Scarsdale diet was classed by many experts as too extreme – even dangerous – high-protein diets have proved an effective weight-loss tool in many situations. The science is that protein reduces levels of the hunger hormone ghrelin, while boosting the appetite-reducing hormones GLP-1, peptide YY and cholecystokinin. In short, it’s not a miracle: you feel less hungry, so you eat less.
“A high-protein diet is key to successful weight loss as protein helps you to feel full while you are reducing calories,” says Zoe Wilson, accredited practising dietitian and accredited nutritionist. “But it’s important to know that there is no need to eat huge slabs of meat at every meal. Protein should take up a quarter to a third of your plate, with a balance of vegetables or salad plus some carbohydrate and healthy fats for a great balance.”
What about plant-based proteins?
Increasing numbers of shoppers are choosing plant-based alternatives in the meat and dairy aisles. Sales of meat substitutes have jumped 60% over the past two years, driven largely by better-tasting products and more choice. Where once the soy burgers languished in a dimly-lit corner of the fridge, plant-based meat, dairy and desserts now have their own ‘alt-protein’ aisle.
But buyers should beware. While plant-based products are a great source of nutrients like folate and fibre and are lower in saturated fats than their meaty equivalents, many are found to be lacking in protein, zinc and vitamin B12.
Always consult your GP before making significant changes to your diet.
Healthy Weight for Life program
Do you struggle with your diet? If you’re an HCF member with a BMI of 26 or over and other lifestyle risk factors, you may be eligible for HCF’s Healthy Weight for Life program. You'll be led by trained dietitians and allied health practitioners to help you manange your weight.
Words by Lindy Alexander
Updated July 2022
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