High-protein diets can preserve muscle mass during calorie restriction.

How much muscle did you lose while on that last diet? Too much, probably, according to research showing that dropping pounds could mean losing valuable lean muscle.

A few scientists have even suggested regular dieting could be harmful since muscle is a crucial tissue for so many facets of long-term health.

Dietary protein has long been thought to be the key to protect against dieting-induced muscle loss. Now, a new long-term study from various universities, headed by researchers at the University of Georgia, is confirming that eating higher amounts of quality protein while reducing calories can help maintain muscle mass at the same time as losing weight.

In a 12-month randomized clinical trial, published in Nutrition and Metabolism, subjects went through a four-month period of weight loss followed by eight months of weight maintenance. Scientists randomly placed 130 middle-aged men and women on calorie-reduced diets that were either high-protein (30 percent of intake from protein) or low-protein (15 percent of intake from protein). The two diets were formulated to be equal in total calories, total fat, as well as fiber content. Physical activity was accounted for and found to be similar between the groups.

While both groups lost weight, researchers found that more fat relative to lean body mass was lost in the high-protein group compared to the low-protein group. In the low-protein group there was about a 40 percent loss in lean tissue, while only 21 percent and 25 percent was lost in the high-protein group for men and women, respectively.

This study’s results add to evidence that a diet higher in quality protein during calorie restriction helps to retain muscle mass. The protein content of a meal, especially one high in branched-chain amino acids, including leucine (found in high concentrations in whey protein), has been shown to trigger muscle synthesis and support the preservation of lean muscle mass.  

Dietary protein requirements are usually expressed as 15 to 20 percent of total calorie intake. When someone reduces calories, the amount of protein they eat may drop as a result of decreased overall intake. Generally, individuals may eat too little protein while dieting, promoting a loss of lean body mass. Isagenix Isalean products (Soups, Shakes, and Bars) as well as IsaPro and IsaLean Pro offer 18-35 grams of leucine-rich whey protein to help preserve your lean muscle mass while losing fat.


Evans EM, Mojtahedi MC, Thorpe MP, Valentine RJ, Kris-Etherton PM, Layman DK. Effects of protein intake and gender on body composition changes: a randomized clinical weight loss trial. Nutr Metab (Lond) 2012;9:55. DOI:10.1186/1743-7075-9-55