Now, I don't know whether it's true what some people in Germany say, i.e. that gripes and clogged kidneys were invented in days, when both bread, and even more so meat were rare to have a better reason than "there is not enough food" to tell your children, when they were about to "overeat" on either of the two is obviously, but in the end, I would not wonder if the underlying reason for a USDA intake recommendation was - as it is with the "good" cereals and grains - an economic one.
Enough of the ranting, though, if you take a closer look at the study itself you will see that the design was kept as simple as possible. Antonio et al. grabbed a bunch of suicidal (who else would dare eating >5x more protein than the holy RDA allows? ;-), but otherwise healthy resistance-trained men and women who had been resistance training regularly for the last 8.9 ± 6.7 years and an average of
8.5 ± 3.3 hours per week who were unequally randomized to a control (CON n = 10) or high protein diet (HP n = 20) group.
"The purpose of unequal randomization was to take into account the loss of subjects from potential lack of compliance due to the high protein diet as well as gaining additional information on the treatment itself." (Antonio. 2014)While the individuals in the control group were advised to maintain the same dietary and training habits over the course of the study. The subjects in the high protein diet group had a clear order that read: "Consume 4.4 grams of protein equal to 4.4 g/kg/d." (Antonio. 2014)
307g of ptorein per day at only 2835kcal? No problem if you have protein shakes
For the average study participant trying to live up to this demand yielded an average protein intake of ~307g protein per day. Needless to say that the latter induced a significant shift in the macronutrient composition, as well as an unfortunately undocumented shift in food quality (I will write more about this in the bottom line).
|Figure 1: Macronutrient composition (g) during the 8 week experiment and changes in energy intake (pre vs. post)|
With only 226g of carbohydrates the previously mentioned dietitians would call this "a dangerous high protein low carb diet that ignores the fundamental need of the food industry to sell tons of healthy grains"... obviously they would not say the stuff after the "that...", but I think you are getting the idea here. What we are dealing with is in fact a high protein, albeit rather lowish carb diet, that delivers the baseline amount of carbohydrates I have suggested in "Carbohydrate Shortage In Paleo Land" (read the whole article) along with a little extra that keeps their energy levels stable, in spite of regular workouts and prevents the dreaded liver glycogen depletion on real low carbohydrate, but due to very high protein intakes non-ketogenic diets that's carrying off one mislead trainee after the other, these days.
If you look at the study outcomes in Table 1, there are - aside from the previously hinted at non-fatal nature of the diet - a couple of other interesting things to observe - most importantly: No changes in body composition!
|Table 1: Changes in body composition pre vs. post 8 week high protein vs. placebo intervention, absolute values,|
(BW: body weight, FFM: fat free mass, FM: fat mass, %BF body fat %; Antonio 2014)
Now, in view of the way protein is glori- and carbs villified these days in the fitness industry, some of you may find that surprising or disappointing. I for my part would rather say that it confirms what you all should know: More protein does not build more muscle (learn more)! That's not "bad". That's basic physiology that is rooted in the same processes as the non-existent weight gain, Antonio et al. rightly consider to be the "key finding in the present study." (Antonio. 2014) - yes, as surprising as it may seem, the study at hand really is, the
"first investigation in resistance-trained individuals to demonstrate that consuming a high protein hypercaloric diet does not result in a gain in fat mass." (Antonio. 2014)We have tons of studies on the effects of high protein diets in low-energy intake (hypocaloric) scenarios, but overeating on protein is news.
With the Bray study (read more) we had a completely different scenario. The corresponding experiment in the course of which the subjects gained a significant amount of body fat on a "high protein" (Bray's interpretation) diet, we do still have a candidate that can help us explain the lack of body fat gain in the study at hand. In said study, the fat gain in the high protein group was after all slow compared to the one that occurred in the subjects who were overeating (+40%, by the way ) on fat, and carbohydrate. It's the "effort" (kcal = energy loss) that's connected to the use of protein as a source of gluconeogensis and the additional energetic effort that's required to turn this newly formed glucose into fat and store it that explains a large part of the observations in both, the Bray study and the study at hand (Antonio. 2014).
- Antonio, Jose, 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 11.1 (2014): 19.
- Bray, George A., et al. "Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial." JAMA 307.1 (2012): 47-55.