A study found in the Journal of the International Society of Sports Nutrition took a look at the effects of trained individuals consuming five and a half times the recommended daily intake of dietary protein (4.4g/kg/d).
The consumption of dietary protein is important for resistance-trained individuals. It has been posited that intakes of 1.4 to 2.0 g/kg/day are needed for physically active individuals. Thus, the purpose of this investigation was to determine the effects of a very high protein diet (4.4 g/kg/d) on body composition in resistance-trained men and women.
Study after study has proven the effectiveness of diets with higher than recommended amounts of protein for healthy body composition. However, many individuals still believe discount these studies for a number of reasons including the belief that eating too much protein can be unsafe or unneeded.
Protein is the most important macronutrient vis-à-vis positive alterations in body composition. Previous work has suggested that protein intakes in the range of 1.2-2.0 grams per kilogram (kg) body weight per day (g/kg/d) are needed in active individuals [1-7]. In contrast, the US recommended daily allowance (RDA) for protein is 0.8 g/kg/d. The average protein intake for US adults is 91 grams daily or ~1.0 g/kg ideal body weight . Thus, the average US adult consumes slightly more than the RDA; however, this level is inadequate for athletes or active individuals who engage in exercise/sport training for several hours per week.
There are a couple very interesting points of interest to discuss from this study. First, the participants in this study consuming a high protein diet (4.4g/kg/d) did not gain any weight (fat, or fat free mass) during the 8 week study, despite the fact that they consumed 800 calories more per day than baseline.
The current investigation found no changes in body weight, fat mass, or fat free mass in the high protein diet group. This occurred in spite of the fact that they consumed over 800 calories more per day for eight weeks. The high protein group consumed an extra 145 grams of protein daily (mean intake of 307 grams per day or 4.4 g/kg/d).
But calories are calories right? Most nutritionists or "experts" will tell you that in order to lose weight you need to consume fewer calories than you burn in order to lose weight. Well, that may still be true, but don't always assume that eating more will make you gain weight either. This is especially important for those of us that wish to either lose weight or maintain weight but are too damn hungry trying to stick to a specific caloric goal. Instead, reach for a high-protein snack.
One might suggest that the high thermic effect of protein may make it difficult to gain body weight during times of overfeeding. It has been shown that the greater the protein content of a meal, the higher the thermic effect . Both young and old individuals experience an increase in resting energy expenditure after a 60 gram protein meal (17-21% increase) .
For those of you who remember your high school or college physics classes should remember the first law of thermodynamics - heat is a form of energy. The heat that your body is constantly producing are calories being burned (used).
This study is also quite telling for those who are either too shy to do resistance training or are trying to add mass from resistance training.
First, those of you who may not do enough resistance training due to a fear of becoming "too bulky," realize that these study participants are training hard, eating 800 calories more than usual every day, not to mention consuming 4.4g/kg/d of protein, and didn't gain any weight at all.
Those of you who are trying to add some mass, realize that more protein is not always the answer. Sure, your body will need protein to build tissue, however, more protein is not necessarily better in building more mass. Your body can only synthesize so much protein at a time (around 0.25-0.5 pounds of new muscle/week) so aim for around 2g/kg/d of protein and fill the rest of your diet in with carbohydrates and fats.
Future research should focus on trained subjects using a single source of protein during overfeeding. Furthermore, a heavy resistance program geared towards skeletal muscle hypertrophy in conjunction with protein overfeeding needs further investigation.
I appreciate the mention of these topics of future research. The participants of the study used whey and casein protein powder supplements to reach their daily protein goals, so it would be interesting to see what results a similar study found if individuals used only whole foods rather than supplements (is it even possible to eat that much protein?).
Also, would there be any difference in weight gain and fat free mass gain if participants were doing a hypertrophy-specific resistance training program.
Tyler Robbins B.Sc. CSCS
Director of Fitness
Head of CrossFit