A high-protein diet is a diet in which 20% or more of the total daily calories comes from protein. Most high protein diets are high in saturated fat and severely restrict intake of carbohydrates. Example foods in a high-protein diet include lean beef, chicken or poultry, pork, salmon and tuna, eggs, and soy. High-protein diets are considered a type of fad diet and have received criticism from the medical community for increasing health risks and promoting misconceptions about carbohydrates, insulin resistance and ketosis.
Health effects
The diet has been described by nutritionists as unhealthy and unbalanced. In 2001, the American Heart Association’s Nutrition Committee issued a strong recommendation against high-protein diets such as Protein Power and the Atkins diet. The committee noted potential health risks of high-protein diets and how there are no long-term scientific studies to support their efficacy and safety. A 2011 review concluded that a "long-term effect of high-protein diets is neither consistent nor conclusive." A 2014 review noted that high-protein diets from animal sources should be handled with caution. High-protein diets can cause a build-up of ketones in the blood which can cause the body to produce high levels of uric acid, a risk factor for gout and kidney stones. High protein intake on the order of 200 g per day, coupled with inadequate intake of other calorie sources, can cause a form of metabolic disturbance and death commonly known as rabbit starvation. Even when consuming other calorie sources, consuming more than 285 g of protein per day may be unsafe. Endocrinologist Robert H. Eckel has commented that "It's important for the public to understand that no scientific evidence supports the claim that high-protein diets enable people to maintain their initial weight loss." High-protein diets may strain the kidney. An increased load on the kidney is a result of an increase in reabsorption of NaCl. This causes a decrease in the sensitivity of tubuloglomerular feedback, which, in turn, results to an increased glomerular filtration rate. This increases pressure in glomerular capillaries. When added to any additional renal disease, it may cause permanent kidney damage. A 2017 review paper in The New England Journal of Medicine suggests that high protein diet may contribute to life-long risk of kidney damage including chronic kidney disease. Although this was disputed in a different review, a year later. In 2019 two new studies concluded that "a high-protein diet is not as safe as claimed, as it may compromise kidney health and result in a more rapid kidney function decline in individuals or populations at high risk of CKD". High protein diets that are high in animal protein and lack fiber, minerals and vitamins increase the risk of coronary artery disease, cancer and osteoporosis. Vitamin B deficiencies can develop if the diet is followed for a long period and negative effects associated with the diet include bad breath, constipation, fatigue and nausea. Legumes and nuts provide dietary fiber, which meat lacks.
Sports training
While elevated amounts of protein consumption are beneficial during athletic training, particularly when attempting to gain muscular mass and strength, there is little evidence of any benefit from increasing protein intake above 2 g/kg bodyweight/day.
Notable high-protein diets
The following high-protein diets have been criticized as fad diets :
