It is touted as a weight-loss hack, a way to stave off illness and injury, and is even promoted by government officials as a cornerstone of healthy eating.
High-protein diets, once the preserve of bodybuilders, have gone mainstream, with grocery store shelves now packed with protein-enriched products, from yogurts and pretzels to cereals, breads and even ice cream.
The message seems simple: more protein is better.
But a major new review is challenging years of messaging that higher protein intake – a trend dubbed ‘protein-maxxing’ on social media – is inherently healthier, suggesting that the benefits may have been overstated.
In a review of more than 350 studies published last week, researchers found that lower-protein diets were linked to a healthier weight, a lower risk of cardiovascular disease and, in some cases, a longer life.
Now, speaking to the Daily Mail, dietitians have warned that the high-protein craze could have the opposite effect to the one many followers are hoping for – contributing to weight gain and increasing the risk of a range of health problems.
‘Some people have the misconception that if you consume too much protein, it just kind of disappears,’ said Lindsey Schoenfeld, a US dietitian. ‘But studies show that consuming a high-protein diet may cause weight gain, diabetes and many other health problems.’
So has the protein boom gone too far – and how much do we actually need to stay healthy without putting our long-term health at risk?
US officials have urged Americans to eat more protein. The science behind this couldn’t be less settled
Protein is an essential nutrient, needed for building and repairing tissue, maintaining the muscles, supporting the immune system and keeping organs, skin, hair and nails healthy.
It is one of three essential macronutrients, alongside carbohydrates and fats, that the body needs in large amounts to stay healthy.
Protein is also particularly important for older adults, helping to preserve strength and mobility, and keep someone independent and well later in life.
For years, the US Government recommended about 0.36 grams (g) of protein per pound of bodyweight (0.8g per kilogram) daily.
But under the latest guidelines released in January this year, this was revised up to 0.54g to 0.72g per pound bodyweight (1.2g to 1.6g per kilogram).
Backed by Health and Human Services Secretary Robert F Kennedy Jr, he said protein had been ‘wrongly discouraged’ for too long. Other influencers such as the Liver King and Joe Rogan have also pushed the benefits of a high protein diet.
For the average 170 lb American woman, that equates to roughly 92g to 122g protein a day. For the average 200 lb man, it’s around 108g to 144g.
To put that into perspective, a three-ounce serving of cooked chicken breast contains around 26g to 30g protein, while a large egg provides about 6g, a cup of Greek yogurt about 20g to 25g, half a cup of firm tofu about 22g, and a cup of cooked lentils around 18g.
But protein isn’t just found in meat and dairy.
Almost every food contains at least some protein – oats provide about 5g per cup cooked, broccoli around 4g per cooked cup, two slices of wholemeal bread about 8g, peanut butter 7g per two tablespoons, and even a medium baked potato around 4g.
It means most people are adding to their daily protein intake with virtually every meal and snack they eat.
That means a woman aiming for the lower end of the recommendation could reach her target with, for example, a cup of Greek yogurt for breakfast (25g), a chicken breast at lunch (30g), a cup of lentils with dinner (18g) and two eggs as snacks (12g) – a total of about 85 grams, with the remaining protein easily made up from grains, vegetables and dairy consumed throughout the day.
A 200-pound man aiming for the upper end of the range, meanwhile, could hit around 140g by eating two chicken breasts (about 60g), a cup of Greek yogurt (25g), a cup of lentils (18g), two eggs (12g) and half a cup of tofu (22g).
The downsides of getting too little protein are well established.
Brittle hair and nails are often among the first warning signs, but deficiency can also lead to muscle loss, weakness and frailty, increasing the risk of falls and bone fractures.
Yet the average American already gets plenty of protein – around 0.6g per pound of body weight each day, enough to comfortably meet current recommendations for most adults.
By contrast, fiber – which has been linked to a lower risk of heart disease, type 2 diabetes, bowel cancer and obesity – remains the nutrient Americans are far more likely to be missing. Around 95 percent of adults fail to consume the recommended amount.
The Health and Human Services Secretary is famous for his meat-heavy diet. He is shown above enjoying a steak for his 72nd birthday in January this year
So, what happens if you eat more protein than experts recommend?
Well, more isn’t necessarily better, for a start – and the evidence suggests there is a ceiling to protein’s benefits.
One of the largest reviews ever conducted on the subject found that once total protein intake reaches around 1.6g per kilogram of body weight a day, consuming more – whether from shakes or food – does not produce any further gains in muscle mass or strength.
The 2018 meta-analysis, led by researchers at McMaster University and published in the British Journal of Sports Medicine, found this was the case even in people lifting weights regularly.
Some studies have found that high-protein diets can help people lose weight. But these trials are typically short – lasting just a few weeks or months – and usually involve people cutting calories and exercising regularly.
In other words, participants are not simply adding more protein to their diet. They are replacing other foods, reducing their overall calorie intake and following a structured weight-loss program.
Longer-term studies suggest any advantage is far more modest, with one review finding high-protein diets offered only a small benefit for maintaining weight loss after a year or more.
There are also concerns that eating too much protein could actually contribute to weight gain.
A 2013 study involving nearly 400,000 people found those getting at least 20 percent of their calories from protein – generally considered a high-protein diet – were 24 percent more likely to become overweight or obese over the following five years than those eating less protein.
Dietitians say the more likely explanation is that people increase their protein intake by eating more calories overall or by relying on fatty cuts of meat and processed foods.
‘Many people interpret a high-protein diet as a green light to eat as much fatty red meat, processed meats such as bacon, and protein-fortified snacks as they like,’ said Lindsey Schoenfeld, a US dietitian.
‘In reality, they’re simply consuming excess calories.’
A typical 12oz sirloin steak contains about 700 calories and 38g of fat. But a ribeye contains 900 calories and 65g of fat.
For comparison, a 12oz portion of chicken breast contains 580 calories and 12g to 14g of fat, while the same amount of cod contains 300 calories and 9g of fat.
Many products now prominently advertise their protein content on the packaging – from breakfast cereals and popcorn to chocolates and Pop-Tarts – in a clear attempt to cash in on the high-protein craze.
But does adding protein actually make these foods healthier?
Dietitians say not necessarily. Many are still ultra-processed products that are high in calories, added sugars or saturated fat. While they may contain more protein than their conventional counterparts, they are often far from the healthiest way to get the nutrient.
‘People see “high protein” on the label and assume they can eat more of it,’ said Lindsey Schoenfeld, a US dietitian. ‘But calories still count.’
There are also several longer-term health risks that experts say are worth considering.
For some people, the kidneys may be particularly vulnerable. Around one in ten people are thought to carry genetic variants that reduce the kidneys’ ability to cope with very high protein intakes, potentially increasing their risk of kidney disease over time.
The source of the protein also matters. Diets high in red and processed meat tend to be rich in saturated fat, which has long been linked to an increased risk of heart disease.
There is also evidence that very high protein intakes may be associated with cancer and a shorter lifespan.
A 2014 study led by researchers at the University of Southern California, involving more than 6,000 adults over 50, found that people consuming high-protein diets – where protein accounted for about 20 percent of calories – had a higher risk of cancer, diabetes and death during the study period.
Animal studies have also suggested that protein-heavy diets may accelerate aging, although it remains unclear whether the same effect occurs in humans.
Pictured is Jack Lalanne, considered the spiritual founder of today’s fitness movement. He ate a high protein diet before it was trendy and died aged 96 years old in 2011
Finally, experts say that focusing too heavily on protein can come at the expense of other nutrients.
People eating large amounts of meat and protein-fortified foods may consume fewer fiber-rich foods such as whole grains, beans, fruit and vegetables – despite strong evidence that fiber lowers the risk of heart disease, type 2 diabetes and colorectal cancer.
So, how much protein should we actually be eating?
Dr Don Layman, a leading researcher at the University of Illinois who helped develop the latest dietary recommendations, said the previous guideline reflected the minimum needed to prevent deficiency, while the newer advice is intended as a target for optimal health.
But dietitians say most people don’t need to obsess over hitting a specific number each day.
Instead, they recommend focusing on a variety of high-quality protein sources – including poultry, fish, eggs, dairy, beans, lentils, tofu, nuts and seeds – rather than ultra-processed foods marketed as high in protein.
Simple changes, such as adding nuts and seeds to yogurt or including beans with a meal, can easily boost protein intake without relying on fortified snacks or shakes.
For most Americans, however, the bigger nutritional concern isn’t protein at all. It’s fiber.
While the average American already consumes enough protein to meet recommended intakes, about 95 percent fail to get enough fiber – a nutrient linked to a lower risk of bowel cancer, heart disease and type 2 diabetes.
‘I do hope the craze moves to fiber next,’ said Lindsey Schoenfeld. ‘With 95 percent of Americans not getting enough, that’s where we really need to focus.’