Sophie Egan
If you’ve browsed the packaged food aisle of a grocery store, or scrolled your social media feed lately, you might think that when it comes to protein, more is better.
Packaged cereal, popcorn, pancake mix and coffee drinks are being infused with the nutrient. In the US, the Trump administration’s new inverted food pyramid features protein prominently, with steak, chicken and cheese at the top.
Protein is an essential nutrient. But more is not necessarily better, says Bettina Mittendorfer, a professor of nutrition and exercise physiology at the University of Missouri School of Medicine. And in some cases, eating much more than what nutrition experts recommend can come with some risks.
There isn’t a strict rule for how much protein is too much, experts say, and many people can exceed recommended amounts with no issues. But potential problems could arise when people ate much more than about1.2 grams of protein per kilogram of body weight per day, Mittendorfer said. Here are some of those concerns.
Heart disease and type 2 diabetes
Most of the protein that Australians eat comes from meat and other animal products. In one study published in 2025, researchers found that animal foods accounted for nearly 55 per cent of people’s protein consumption.
Research suggests that those who eat larger amounts of red and processed meat tend to have higher risks of heart disease and type 2 diabetes, according to Dr Donald Hensrud, an associate professor of nutrition and preventive medicine at the Mayo Clinic College of Medicine in Minnesota.
In one large analysis published in 2023, for instance, researchers found that eating an extra 100 grams of red meat (equivalent to about one thin, boneless pork chop) a day increased the risk of heart disease by 11 per cent – and every additional 50 grams of processed red meat (equivalent to about one standard hot dog) a day increased it by 26 per cent. Another study, also published in 2023, found that among the nearly 217,000 (mostly female) participants, those who ate the most red meat had a 40 per cent higher risk of developing type 2 diabetes than those who ate the least, and that those who ate the most processed red meat had a 51 per cent higher risk.
Red and processed meats tend to contain high levels of saturated fats, which can raise blood levels of LDL (or “bad”) cholesterol and increase the risk of heart attack and stroke. These foods might also increase inflammation and insulin resistance, Hensrud said, which could raise the risks of heart disease and type 2 diabetes as well.
Cancer
Consuming excess red and processed meat could also increase the risk of cancer, especially colorectal cancer, Hensrud said.
In one study published in 2024, researchers found that diets high in red meat were linked with a 30 per cent increased risk of developing colorectal cancer, and that those high in processed meat were linked with a 40 per cent increase in risk.
Dr Dariush Mozaffarian, a cardiologist and director of the Food Is Medicine Institute at Tufts University in Boston, said that plant sources of protein such as soy, lentils, beans and nuts – as well as fish and fermented dairy products like yoghurt – were much healthier options.
People who prioritise vegetables, fruits and whole grains, along with lean or plant-based proteins, are less likely to develop certain types of cancer (as well as cardiovascular disease and type 2 diabetes).
Constipation and other digestive concerns
People who were focused on increasing their protein consumption (especially those on low-carb diets) sometimes inadvertently left out high-fibre foods, such as vegetables and whole grains, said Marc O’Meara, a nutritionist at Brigham and Women’s Hospital in Boston.
Fibre was essential for keeping your intestines and gut microbiome healthy, he said. It helps keep your bowel movements regular and serves as food for your gut microbes. Diets higher in fibre could also reduce the likelihood of developing certain gut disorders, such as irritable bowel syndrome, he said.
O’Meara recommended aiming for equal portions of vegetables, protein and whole grains at most meals. Or, if you’re trying to limit calories to lose weight, he said, make half of the plate vegetables and a quarter each protein and whole grains.
Weight gain
A popular claim on social media is that you must follow a high-protein diet if you want to lose weight or gain muscle. But if you’re not doing enough strength training or other exercise to match your increased protein consumption, Mozaffarian said, any excess calories, including those from protein, will be turned into fat.
O’Meara also noted that favouring protein-rich foods over vegetables could lead to weight gain. A half-cup of cooked vegetables, for instance, had an average of about 25 calories, whereas a half-cup of cooked chicken had about 140 calories, he said. If you tripled a serving of chicken to eat more protein, you would consume five to six times as many calories as you would if you tripled a serving of vegetables, O’Meara said.
Kidney issues
If your kidneys are healthy, you probably don’t need to worry much about excess protein consumption, according to Hensrud. However, for the more than one in seven Americans with chronic kidney disease – especially those who may be close to needing dialysis – metabolising large amounts of protein could stress the kidneys, Hensrud said, further reducing kidney function.
Kidney stones were also a potential side effect of consuming too much animal protein, Hensrud said. If you drink enough water, however, your risk is far lower.
Make the most of your health, relationships, fitness and nutrition with our Live Well newsletter. Get it in your inbox every Monday.
This article originally appeared in The New York Times.
