A study by the U.S. Army Research Institute of Environmental Medicine found that increasing protein consumption beyond the recommended dietary allowance (RDA) during weight loss can reduce lean body mass loss, while maintaining overall weight loss.
Three different groups were compared in the study. All groups had an equal energy deficit but the protein content varied among groups. One group consumed the RDA of protein (0.8 g protein/kg body weight), while the other groups consumed two or three times the RDA. A total of 39 healthy military personnel (BMI= 22-29) were included in the study.
After 21 days, weight loss was similar among the groups (3.2 +/- 0.2 kg). However, the groups that ate more protein lost a higher percentage of fat and a lower percentage of lean mass. Only 42% of the weight lost by the RDA group was fat mass, compared to 70% for the 2x-RDA group, and 64% for the 3x-RDA group.
The results demonstrate that consuming twice the RDA of protein can preserve lean mass while increasing the proportion of fat lost. However, increasing protein consumption more than twice the RDA does not provide an additional benefit.
To put the numbers in perspective, a 200 pound man’s RDA of protein is about 72.5 grams per day. Based on the results of the study, doubling the protein intake to 145 grams per day would preserve lean body mass while maintaining overall weight lost. A 140 pound woman’s RDA of protein is about 50 grams and doubling this amount would yield 100 grams of protein per day.
To figure out your RDA of protein:
(Your Body Weight in Pounds / 2.205 lb/kg) x .08 grams/day = RDA of protein
Doubling this number will provide the optimal amount of protein according to this study.