It’s 20 years since Professor David Raubenheimer and his colleague Professor Stephen Simpson came up with the protein leverage hypothesis.
Their groundbreaking work shifted the dial from an emphasis on fat and carbohydrate consumption to focus on the role of protein in moderating weight gain.
Protein has taken over more than the gym.Credit: Getty Images
“We have shown that humans, like our nearest primate relatives and many other animals, have a powerful and specific appetite for protein,” say the professors at the University of Sydney’s Charles Perkins Centre.
“Because protein has become diluted in the food supply by the massive influx of ultra-processed foods (UPFs), this has led to our overeating calories to reach our protein target – what we call the Protein Leverage effect.”
Today, in the midst of an obesity epidemic and the desire for a lean and toned body stronger than ever, simply adding protein to UPFs has been sold as the solution – and food companies are cashing in.
A quick scope of Woolworths and Coles showed more than four times as many “protein” products as “reduced fat” products and more than double the amount of “low sugar” products.
From protein water, with 30 grams, FroPro (frozen protein pizza) and YoPRO (protein-enhanced yoghurt) to Pro Puffs (cereal), ProPud (dessert), protein bars and cookies, the marketing opportunities are endless.
Nutrition scientist Dr Joanna McMillan says the obsession has become “crazy”.
“Adding protein to an ultra-processed food does not make it healthy,” she says.
A study published in Nature Metabolism in March found that adding extra protein to ultra-processed foods makes us eat slightly less, but not so much that we stop at one or two.
“Reformulating UPFs by adding protein is [not] an antidote to low-protein UPFs,” says Simpson.
That’s because UPFs are still designed to encourage over-consumption, with their low fibre content, flavour enhancers, and hyper-palatable lashings of sugar, fat and salt.
“Merely adding more protein is putting lipstick on a pig (not wishing to insult pigs).”
Now we can also buy protein powders which, thanks to marketing campaigns and social media, are no longer the domain of body builders and gym junkies. Whey, once a surplus product of the dairy industry regarded as waste and fed to pigs and cattle or used as fertiliser, is now transformed into protein powders at about four times the cost of a litre of milk. It is helping to fuel a multibillion-dollar industry.
Protein shakes have become a status symbol, an accessory to our activewear and a symbol of who we are and what we value.
We have become a nation obsessed: protein was the most frequently mentioned nutrient of 2024.
More than once, Dr Evangeline Mantzioris has asked her students studying nutrition and food sciences at the University of South Australia why they are eating ultraprocessed protein bars.
“They say, ‘I’m eating my macros,’” she says. “I ask them: ‘Well, what have we learned in the degree? Most Australians who are healthy are meeting their protein requirements.’”
In fact, 99 per cent of Australians consume enough protein without much effort, yet many of us remain convinced we need more.
More is not always more
Do we need more protein? It depends.Credit: Getty Images
Protein is undeniably important for muscle metabolism, appetite and weight control, but consuming it in excess puts us at greater risk of bone, calcium and kidney disorders, cancer, liver function disorders, and heart disease.
“Eating too much of something is not the best solution to eating too little,” Professor Raubenheimer says.
What is too little or too much depends on the person. The national guidelines for protein are about 0.8 grams per kilogram of body weight. Based on the average weight for Australian men and women (87 kilograms and 71 kilograms respectively), that equates to about 70 grams for men and 57 grams for women.
For those trying to build muscle, consuming more is beneficial. The sports nutrition recommendations are 1.4-to-2 grams per kilogram of body weight.
But, Mantzioris says, unless you are also doing more exercise, consuming more protein is just going to get converted to fat.
Women in peri-menopause and menopause may also benefit from higher amounts (1.2-1.6 grams per kilogram), says McMillan: “The loss of oestrogen leads to not only a loss of bone density but also muscle mass.”
And though, as Simpson points out, humans have “an exquisitely sensitive protein appetite control system” that ensures we don’t eat too little or too much, people who are malnourished, sick and very elderly may need some extra help to meet their requirements under medical guidance.
Regardless, we need to spread our intake across the day, as most people can only digest and use about 30 grams of protein at a time.
“Taking in more will mean some of that protein is … passing through you undigested, potentially leading to fermentation by the microbes in your colon, leading to potentially unhealthy metabolites being released,” says McMillan.
A shaky source?
To shake or not to shake, that is the question. Credit: Getty Images
Protein may be the only nutrient to emerge unscathed from diet wars. Still, there is rigorous debate over animal protein (meat, poultry, fish and seafood, dairy and eggs) versus plant protein (tofu, legumes, beans, nuts and seeds) and whether to shake or not to shake.
The protein package matters, says nutrition scientist and host of The Proof podcast Simon Hill.
“There’s an argument to be made that animal protein is superior if you’re under-consuming protein,” says Hill. “Once you get to 1.2 to 1.6 grams, the differences between animal and plant protein go away.”
For long-term health, including cardiometabolic disease and cancer risk, Hill argues there’s an advantage to swapping calories from animal protein to plant protein.
Says McMillan: “There is no doubt that animal proteins provide all of the essential amino acids, are better absorbed and utilised than plant proteins,” says McMillan. “That is probably more important when protein intakes are lower, as the quality matters more.”
To hit his daily target of 1.6 grams per kilogram, Hill bolsters his protein intake with powder in a smoothie of berries, greens, almond milk and nuts.
Powders can indeed help those with very high protein needs, or those who cannot consume enough whole foods, but for the most part, even if we’re trying to build muscle we can do it without supplements.
Our bodies have evolved to consume whole foods, not highly processed macros outside the matrix – the food matrix, that is.
“The food matrix is the natural complexity of a whole food where many nutrients are intimately connected, bound within the structure of the particular food,” says McMillan. “These all make a difference as to how the food is digested and absorbed, and how the nutrients are metabolised in the body.”
Professors Simpson and Raubenheimer agree. “Protein fortification is largely a marketing strategy for selling profitable UPF. Best to get our protein – and the many other nutrients we need – from real foods … we don’t need protein powders.”
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