A recent review and meta-analysis investigating protein intake conclude that consuming the recommended daily allowance is fine for most people, most of the time. However, more protein is not necessarily beneficial.
Many of us enthusiastically indulge in holiday treats, which means that come New Year's Day, beginning a weight loss program is a common resolution.
An increase in the consumption of protein — often over the recommended daily allowance — is the cornerstone of many diets, but does eating more protein make sense for everyone?
A new study by nutrition scientists at Purdue University in West Lafayette, IN, finds that increasing the intake of protein only provides benefits in certain circumstances. The findings of the research appear in Advances in Nutrition.
The bottom line is that if you are not explicitly dieting for weight loss or weight training, there is no clear benefit to consuming more protein than the minimum daily requirements that the United States Department of Agriculture (USDA) have established.
"[T]here is so much encouragement, advertising, and marketing for everyone to eat higher protein diets, and this research supports that, yes, under certain conditions, including strength training and weight loss, moderately more protein may be helpful, but that doesn't mean more is needed for everybody at all times," explains the lead author, Joshua Hudson.
A normal amount of protein
Commenting on the study's narrow focus, Hudson says:
"This research was not designed to assess whether or not adults would benefit from consuming more protein than they usually consume. This distinction is important because the recommended dietary allowance is the standard against which to assess nutrition adequacy; however, most adults consume more protein than what is recommended."
According to the USDA's Dietary Reference Intakes (DRI), the desired daily amount of protein is 0.8 grams (g) per kilogram of body weight, which equates to about 0.36 g of protein per pound each day. Based on this, 56 g per day is suitable for the average, generally healthy sedentary male, while a similar female should aim for 46 g. It is important to note that these recommendations do not apply to people with type 2 diabetes.
The USDA list a range of food sources from which to get that protein, including seafood, meats, poultry, eggs, nuts, seeds, and soy products.
The study's methodology
Hudson and his colleagues began by looking at more than 1,500 articles on nutrition that they found in nutritional databases. From these, they identified 18 papers for closer examination.
The authors chose these papers for their inclusion of healthy adults and their focus on certain topics, including protein consumption, physical activity, and weight loss. Together, the research encompassed 22 interventions involving 981 individuals. The sources of protein that the participants consumed included lean and minimally processed meats, dairy, eggs, nuts, seeds, and legumes.
The data revealed that for everyday life — when individuals are neither gaining nor losing weight — eating more than the recommended amount of protein does not do anything for body composition.
The study reports no harmful consequences, simply no effect at all, be it negative or positive.
A higher intake of protein only enhances lean mass in people who are consciously dieting or engaging in weight training.
Too little protein, however, is a problem, says study co-author Campbell, who explains, "This research is clinically more important for women and especially older women who are known to typically consume lower amounts of protein and should be maintaining a healthy body weight and regularly strength training."
As far as holiday eating goes, Campbell offers the following advice: "If you are going to start losing weight, don't cut back across all foods you usually consume, because you'll inadvertently cut back protein. Instead, work to maintain, or even moderately increase protein-rich foods. Then, cut back on the carbs and saturated fat-containing foods."