A Tale of Macro- & Micronutrient Modifications: Eating "Unlimited Protein" Will Make You Fat. A Hypercaloric Low Protein Diet With a Large Amount of Arginine Won't!
|Image 1: The main message of the Bray study (according to Bray himself is) that you won't get away with consuming way more energy than you need - no matter how much of this energy comes from protein.
The nitty gritty on overeating: Eat 140% of the energy you expend and get fat - no matter what!
The one difference a higher protein intake on a hyper-caloric diet makes - and I am certain that you will have been aware of that - is that overeating on protein will help stimulate muscle protein synthesis and thusly facilitate increases not only in fat, but also in lean mass. Now, while this obviously is a good thing (compared to gaining fat, only), you should be aware that "gains" like that won't be particularly aesthetic. After all, even the subjects in the high protein group gained more fat than muscle and though the difference was statistically insignificant, the mere fact that you have more muscle than fat tissue should tell you that your body fat percentage increases even if you gain identical amounts of fat and muscle weight. So, I guess that the average participant of the Bray study was probably not very pleased with the way he looked when the study was over.
|Figure 1: Composition of the diet of the participants at baseline and during the 8 week intervention period (left); lean body mass and fat mass (in kg) of the participants before and after the intervention (right; data calculated based on Bray. 2011)
An arginine rich low protein diet builds muscle, and melts away body fat
Allegedly, this is only another rodent study, but hey, haven't we been able to predict the outcome of the Bray study based on previous data from rodent studies, as well? Yes, we have! So, bear with me, because the effects the 10% total protein, of which ~8% came from casein and 1.8% from supplemental l-arginine (cf. figure 2) had on the body composition of the 6 week-old mice in the Clemmenson study, were pretty astonishing (Clemmenson. 2011).
|Figure 2: Macro- and micronutrient (protein component) composition of the diet the control and arginine groups of the Clemmenson study were fed in the course of the 10-week intervention period (Clemmenson. 2011)
|Figure 3: Additional cumulative energy intake over 21day and 72h period, as well as reduction in feed efficiency in l-arginine fed mice over 21day period (left); total body weight over the course of the whole study (right; data based on Clemmenson. 2011)
|Figure 1: Body composition and fat weight of mice after 10 weeks on normal and high l-arginine diet low-protein diet (data based on Clemmenson. 2011)
Micronutrient (l-arginine) mediated modulation of insulin sensitivity as a key to lean gains
OGTT and ITT, performed at week 8 and 9, respectively, demonstrated that L -Arg supplemented mice were signifi-cantly more glucose tolerant (34% reduction in AUC, P < 0.03) and insulin sensitive than mice on the control diet. Fasting blood glucose levels were significantly lower in the L -Arg supplemented group (7.9 ± 0.4 mmol/L) compared with the control group (9.7 ± 0.2 mmol/L, P = 0.003), but basal plasma insulin concentrations after 10 weeks on the diet did not significantly differ between the two groupsNow, don't get me wrong (I know you will ;-), I am not saying that eating a low-protein diet with "huge" amounts of l-arginine in it (the human equivalent, by the way, would have been ~0-8g/kg body weight) is going to turn you into a ridiculously ripped mass monster. I am just trying to make a point that we are only scratching the surface, when we focus solely on the "good protein", the "bad carbohydrates" or the "good and bad fats"... and that the body fat of the mice in the Clemmenson correlated with total insulin only in the "control", yet not in the l-arginine group (cf. figure 5), goes to show that even the contemporary vilification of insulin will probably have to be re-evaluated in light of the effects the identical levels of insulin can have on the body composition and other important health factors in different dietary contexts, individuals and probably even time-points.
Note: As soon as I find the time I am going to write something more comprehensive on the whole "how much protein is enough and when can it even become detrimental"-issue... promise ;-)So, before you jump aboard the boat of any "unlimited whatever" nutritional strategies, you better focus on the myriad of small adjusting screws, which will all have to be in place to optimize firstly your health and if that is in place, secondary your performance or body aesthetics.... and I guess, I don't have to remind you that the SuppVersity is the place to go for your daily dose of information that will help you not to "screw up" ;-)