Does eating copious amounts of protein make you fat? That's the question researchers from Florida, USA were trying to answer in a recent study published in the May issue of the 2014 Journal of the International Society of Sports Nutrition.
What is a copious amount of protein you ask? How does 4.4g per kilogram bodyweight sound? When you consider that the conventional upper limit of protein intake is around 2g/kg bodyweight, 4.4g/kg bodyweight is a massive amount of protein.
The researchers conducted the study on a group of otherwise healthy male and female subjects who had been engaged in resistance training regularly for the last 9 years on average, and training for an average of 8.5 hours per week. Subjects were assigned to either a control or high protein group. The control group were simply instructed to maintain their normal diet and training regime.
While kidney and liver damage are some of the conventional concerns associated with very high protein intakes, the authors of this study were primarily concerned with the effect on body composition. Part of what the researchers were trying to explore was the effect of excess calories in the form of protein compared with fat or carbohydrate.
Because 4.4g/kg of protein equates to 330g for a 75kg individual, the most practical way for subjects to meet their target protein intake was by means of a protein supplement, which took the form of a blended whey and casein supplement.
The most significant finding of this extreme study was that after 8 weeks on the super high protein diet, subjects’ body composition did not change significantly; with no observed increase in fat mass. 4.4 g/kg/day of protein is over five times the recommended dietary intake for adults, which makes the findings quite surprising in one sense. So what does the study prove? Well not much other than one is unlikely to die of liver of kidney damage after 8 weeks on a super high protein intake. Plus one is unlikely to put on any weight in the form of fat. But possibly the most important take away is that a ridiculously high intake of protein likely does nothing for putting on extra muscle.
It’s important to note however, that of the 20 subjects initially in the high protein group a total of 10 dropped out. Of these, three citing an inability to consume the protein needed for the study and one subject complained of gastrointestinal distress. 50% is pretty high dropout rate, which suggests maintaining such a high protein take is a challenge. What’s more, the authors did not take any measures of kidney or liver function, so it’s impossible to determine what adverse effects (if any) this levels of protein intake had of these vital organs. This may be a subject of future research.
Antonio J, et al. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. Journal of the International Society of Sports Nutrition. 2014;11:19.