New research from United Kingdom indicates that adequate protein is important when calories are restricted for weight loss. They altered the protein content of a calorically reduced diet to see how it affected changes in lean body mass. Resistance trained athletes were placed on a prescribed diet that contained only 60% of their caloric needs for two weeks. One group ate a diet that contained a typical amount of protein (1g of protein per kilogram of body weight or 15% of total energy), which is roughly about 80g of protein a day for a 180-pound person. The other group ate a higher protein diet (2.3g of protein per kilogram body weight or 35% of total energy), which is roughly 190g of protein a day for a 180-pound person.
At the end of the 2-week study, both groups lost the same fat mass. Unfortunately, however, the lower protein group also lost well over 3 pounds of lean muscle mass. The higher protein group preserved their lean mass.
These findings highlight the importance of consuming adequate protein during low calorie diets to maintain muscle in young healthy athletes.