The Issue [Chapter 1]: Is a High-Protein Diet Safe and Effective for Weight Loss?

High-protein diets are promoted for weight loss. Some of these diets allow all the steak, bacon, and eggs you can eat; others suggest leaner protein choices. Is all that meat good for you? Are high-protein diets effective for weight loss? And, are they healthy?

When talking about a high-protein diet, it’s necessary to define what counts as high protein. Most Americans consume more than the RDA for protein. This gives the impression that we are all eating high-protein diets, but at 16% of calories from protein the typical American diet is at the low end of the AMDR of 10 to 35% of calories from protein. Most studies on the effects of high-protein consider a high-protein diet to be one with 25% of calories or more from protein. For the average person, this is about 134 grams per day, which is equivalent to eating a dozen eggs and a 12-ounce steak every day. Is such a diet the best way to lose weight?

Weight loss requires consuming fewer calories than you expend. So, any diet that limits calorie intake will promote weight loss. Protein is the most satiating of the macronutrients, which is why high-protein diets promote weight loss; the protein keeps you feeling satisfied, so you eat less. Protein also affects energy expenditure. When you eat less to lose weight, your metabolism slows to conserve energy. High-protein diets have been found to cause less of a decrease in energy expenditure than low-fat or high-carbohydrate diets. Some of this may be because the body uses more calories to process protein than it does for carbohydrate or fat, so eating a high-protein diet increases calorie needs. A high protein intake also helps maintain the body’s muscle mass, and the greater one’s muscle mass, the greater one’s calorie needs. So, even people who aren’t counting calories may eat less and expend more energy when consuming a high-protein diet than they would with less protein. So, a high-protein diet may make weight loss easier. But high-protein diets can vary in the amounts of other nutrients. Do the other components of the diet matter?

The amount of carbohydrate in the diet may affect appetite. Some high-protein diets severely restrict carbohydrate. Diets very low in carbohydrate lead to the production of ketones, which further suppress appetite. However, the beneficial effect that a high-protein diet has on weight management has been found to depend on the high-protein component of the diet, not on the low-carb component. Also, severely restricting carbohydrate intake means all but eliminating entire food groups and may not promote weight loss more than would a less restrictive diet.

Does the type of protein you choose matter? A high-protein diet could be high in red meat and high-fat dairy products (see figure), or it could be high in legumes, nuts, fish, and poultry. The source of the protein in the diet, whether plant or animal, does not seem to affect satiety. Plant proteins suppress appetite as well as animal proteins. But the source of the protein may be important for the overall health of the diet. Many high-protein diets are high in animal products and low in whole grains, fruits, and vegetables; this dietary pattern has been shown to promote heart disease. Despite this, improvements in risk factors for heart disease have been seen in the short term with these diets. An analysis of studies of high-protein diets lasting about six months found small improvements in body fat, blood pressure, and triglyceride levels. Even after a year or more, high-protein diets exerted neither specific beneficial nor detrimental effects on risk factors for heart disease. However, when the effect of high-protein diets is followed in the long term (an average of about 16 years), some studies find an increase in heart disease risk and overall mortality as well. Some of the reason for the discrepancy in these results may be the overall dietary pattern; protein sources such as red meat and high-fat dairy products are associated with an elevated risk of coronary heart disease, while higher intakes of poultry, fish, and nuts correlate with a lower risk. Processed meat is also a carcinogen. A dietary pattern that is high in red and processed meat is associated with an increased risk of cancer, especially colorectal cancer. A study that monitored people for 18 years found that those 50 to 65 years of age who had a high protein intake had a 75% increase in overall mortality and a fourfold increase in cancer death risk. These cancer and mortality associations were either abolished or attenuated if the proteins were plant derived.

High-protein diets promote weight loss and weight maintenance and help maintain lean body mass. This is good for your overall health, but if the same diet increases the risk of heart disease and cancer over the long term, is it the best choice?

-Maré Productions

Citation

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