Figuring out whether a high protein diet is healthy or not can leave you scratching your head. Depending on which headline you read a high protein diet can sound like the prince of darkness, raising our risk of diabetes, cancer and an early grave or a saviour come to rescue us all from weight gain and muscle loss.
The problem here is with the term ‘high protein’ because it doesn’t tell us anything about the quality of the whole diet or where the protein comes from, says Associate Professor Tim Crowe of the School of Exercise and Nutrition Sciences at Deakin University.
“If a diet is high in lean sources of animal protein but also high in whole plant foods then it can be healthy. But in research studies high protein is often a marker for a diet that’s high in animal protein and processed food but not much plant food,” says Crowe.
Recent research from the University of California linking high protein diets to a reduced lifespan and increased cancer risk is one example.
“When you look at where the protein was coming from in this study it was those people eating diets high in animal protein that had the higher risk, not those eating protein from mostly plant sources,” he says. “This is why there’s a good argument for eating not just animal protein but also protein from plant foods such as legumes, grains and nuts - this helps you get a broader range of nutrients.
“Where high protein diets are linked to diabetes and other health problems this is likely to be the result of diets high in both processed food and animal protein, not just protein itself.”
So what’s a healthy amount of protein to eat? That depends on age and gender – men need more protein than women and the over 70s need more than younger adults. Current Australian guidelines say that in the 19 to 70 year old age group men need around 64g protein daily, while women need around 46g. For the over 70s, men need 81g daily while women need 57g.
As for where to get your protein, here are some clues: there’s around 10 g of protein in 250mls reduced fat milk, 120g tofu or 200g yoghurt. A cup of cooked legumes has 16g of protein; an egg has about 6g; 150g cooked fish has 36g and 150g beef or chicken has about 40g. Nuts and seeds are easy ways to sneak more plant protein into the day either as snacks or added to muesli, porridge or other dishes. Almonds and pistachios are the tree nuts with the most protein with around 6g protein per 30g handful; a tablespoon of chia seeds has around 3g of protein. Whole grain breads with added seeds are also generally higher in protein than other breads. Using quinoa instead of rice or couscous gives a protein boost – it has double the protein of most grains.
And if you’re heading towards older age, there’s a growing recognition of the need for more protein, along with strength training, to maintain muscle and fend off frailty. There are two ways in which ageing can compromise muscle, says Crowe. Not only does ageing itself bring muscle loss but it also increases the risk of health problems like heart disease and type 2 diabetes - conditions that can go hand in hand with higher levels of inflammatory chemicals in the body called cytokines - and these cytokines can also contribute to muscle loss.
Whatever your age, Crowe also recommends that for building muscle it’s better to spread protein intake evenly across the day rather than eating most of it at dinner because your body can only process around 25 to 30 g of protein at once.
Do you need more protein if you’re a regular exerciser? If you do regular strength training and some running, the answer is yes, he says, pointing to the consensus from scientists at the 2010 International Olympic Committee Conference on Nutrition in Sport which recommended an intake of 1.3 to 1.8g per kilo of body weight per day for athletes and regular exercisers – and to consume some protein less than four hours before training and less than two hours after.
What about protein bars?
“If you have higher protein requirements and you need a snack they can be a good idea but they are expensive,” says Crowe. “It’s good to read the label and look for protein bars that have less added sugar and saturated fats.”