Recent shifts in US dietary recommendations have encouraged Americans to consume more protein, a trend that some experts suggest may be overstated and potentially counterproductive. While protein is essential for bodily functions, a growing body of research and expert opinion raises concerns about the health implications of pursuing excessively high protein diets, often referred to as 'protein-maxxing.'
US officials, including Health and Human Services Secretary Robert F. Kennedy Jr., have advocated for increased protein intake, suggesting it has been "wrongly discouraged" for too long. The latest guidelines from the Health and Human Services have revised the recommended daily protein intake upwards. For an average 170-pound woman, this translates to approximately 92 to 122 grams of protein per day, while for a 200-pound man, it is around 108 to 144 grams.
Protein is vital for building and repairing tissues, maintaining muscle mass, supporting the immune system, and promoting healthy skin, hair, and nails. It plays a particularly important role for older adults in preserving strength and mobility. Previously, the US government recommended about 0.36 grams of protein per pound of bodyweight daily, a figure revised in January of this year to between 0.54 and 0.72 grams per pound.
However, a comprehensive review of over 350 studies suggests that lower-protein diets may be associated with healthier weight, reduced risk of cardiovascular disease, and potentially longer lifespans. Dietitians are warning that the current emphasis on high-protein diets could lead to unintended consequences, including weight gain and an increased risk of various health problems.
US officials have urged Americans to eat more protein. The science behind this couldn't be less settled.
Lindsey Schoenfeld, a US dietitian, noted that the misconception that excess protein simply disappears is incorrect. "Studies show that consuming a high-protein diet may cause weight gain, diabetes and many other health problems," she stated.
The average American already consumes about 0.6 grams of protein per pound of body weight daily, which is sufficient for most adults to meet current recommendations. In contrast, fiber intake remains a significant concern, with approximately 95 percent of adults failing to consume the recommended amount, despite its links to a lower risk of heart disease, type 2 diabetes, bowel cancer, and obesity.
Research indicates that there may be a limit to the benefits of increased protein intake. A 2018 meta-analysis published in the British Journal of Sports Medicine found that consuming more than approximately 1.6 grams of protein per kilogram of body weight daily does not yield further gains in muscle mass or strength, even for individuals who exercise regularly.
While some short-term studies suggest high-protein diets can aid weight loss, these often involve calorie restriction and regular exercise, making it difficult to attribute weight loss solely to protein intake. Longer-term studies have shown only modest benefits for weight maintenance over a year or more.
Concerns also exist that excessive protein consumption could contribute to weight gain. A 2013 study involving nearly 400,000 people found that those deriving at least 20 percent of their calories from protein were 24 percent more likely to become overweight or obese over five years compared to those consuming less protein. This is often attributed to individuals increasing their overall calorie intake or choosing high-fat sources of protein, such as fatty red meats and processed foods.
Many commercially available products are now marketed as "high protein," including cereals, snacks, and even desserts. Dietitians caution that the addition of protein does not automatically make these ultra-processed items healthy, as they may still be high in calories, sugar, or saturated fat. "People see 'high protein' on the label and assume they can eat more of it," Schoenfeld said. "But calories still count."
Longer-term health risks associated with very high protein intake are also a consideration. For individuals with specific genetic predispositions, particularly affecting kidney function, excessive protein could increase the risk of kidney disease. Furthermore, diets high in red and processed meats are often rich in saturated fat, a known risk factor for heart disease. Some studies have also suggested a link between very high protein intakes and increased risks of cancer and a shorter lifespan.
Experts also emphasize that an overemphasis on protein can lead to a deficiency in other crucial nutrients, such as fiber. Those consuming large amounts of protein-rich foods may reduce their intake of fruits, vegetables, and whole grains, which are vital for preventing chronic diseases.
Leading researchers suggest that the previous protein guideline represented the minimum needed to prevent deficiency, while the updated recommendations aim for optimal health. However, dietitians advise against fixating on specific daily numbers. Instead, they recommend focusing on a varied intake of high-quality protein sources like poultry, fish, eggs, dairy, beans, lentils, tofu, nuts, and seeds, prioritizing whole foods over ultra-processed options.
For many Americans, the greater nutritional challenge lies in insufficient fiber intake, with a vast majority not meeting recommended levels. "I do hope the craze moves to fiber next," Schoenfeld commented. "With 95 percent of Americans not getting enough, that's where we really need to focus."