Many people eat far more protein than they need, but while protein is an essential nutrient, too much of a good thing can have consequences, suggest experts in The New York Times.
The packaged-food aisle of grocery stores may give the impression than when it comes to protein, more is better. Packaged cereal, popcorn, pancake mix and coffee drinks are all being infused with the nutrient. And in the US, the new inverted food pyramid, released by the Trump administration in January, features protein prominently, with steak, chicken and cheese at the top.
Yet research suggests that most American adults are eating far more protein than is needed for good health. Protein is an essential nutrient. But more is not necessarily better, said Bettina Mittendorfer, a Professor of Nutrition and Exercise Physiology at the University of Missouri School of Medicine. In some cases, eating more than recommended by nutrition experts can have risks.
There isn’t a strict rule for how much is too much, and many people can exceed recommended amounts with no issues. But potential problems can arise when people eat much more than around 1.2 grams of protein per kilogram of body weight per day, Mittendorfer said. Here are five of those concerns.
Heart disease and type 2 diabetes
Most of the protein eaten by Americans comes from meat and other animal products. In one study published in 2021, researchers from the Department of Agriculture found that animal foods (including beef, chicken and cured meat) accounted for nearly 70% 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, said Dr Donald Hensrud, an associate Professor of Nutrition and Preventive Medicine at the Mayo Clinic College of Medicine.
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) per day increased the risk of heart disease by 11% – and every additional 50 grams of processed red meat (equivalent to about one standard hot dog) per day increased it by 26%.
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% 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% 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 may also increase inflammation and insulin resistance, Hensrud said, upping 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.
In one study published in 2024, researchers found that diets high in red meat were linked with a 30% increased risk of developing colorectal cancer, while those high in processed meat were linked with a 40% risk increase.
Dr Dariush Mozaffarian, a cardiologist and director of the Food Is Medicine Institute at Tufts University, said plant sources of protein like soy, lentils, beans and nuts – as well as fish and fermented dairy products like yogurt – 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 are focused on increasing their protein consumption (especially those on low-carb diets) sometimes inadvertently leave out high-fibre foods, like vegetables and whole grains, said Marc O’Meara, a nutritionist at Brigham and Women’s Hospital in Boston.
Fibre is essential for keeping your intestines and gut microbiome healthy, he said, helping to keep your bowel movements regular and serving as food for your gut microbes. Diets higher in fibre can also reduce the likelihood of developing certain gut disorders, like irritable bowel syndrome.
O’Meara recommended aiming for equal portions of vegetables, protein and whole grains at most meals, or to limit calories to lose weight, 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, has an average of about 25 calories, whereas a half-cup of cooked chicken has about 140 calories, he said. If you triple a serving of chicken to eat more protein, you consume five to six times as many calories as you will if you triple a serving of vegetables.
Kidney issues
If your kidneys are healthy, you probably don’t need to worry much about excess protein consumption, but 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 can stress the kidneys, Hensrud said, further reducing kidney function.
Kidney stones are also a potential side effect of consuming too much animal protein, but drinking enough water will reduce that risk.
The New York Times article – 5 Health Risks From Consuming Too Much Protein (Restricted access)
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