|While being misinterpreted as an "anti-whey" study by one of you, the latest whey as your main protein source study from Brazil only adds to the evidence that there's something special about whey.|
But before we get to the implications and interpretations, let's first take a look at what the scientists did and what they observed. You'll see that this is of paramount importance wrt to not misinterpreting the weight gain in Figure 1.
Being aware that whey protein (WP) is known for its nutritional value and antioxidant properties, the authors speculated that the latter, or rather the protective effect they would have on the muscle tissue, would be another important contributor to Wheys beneficial effects on skeletal muscle development.
To test their hypothesis that a reduced muscle damage and thus reduced effort to rebuild the broken tissue before accumulating new muscle would contribute to the muscle building effects of whey protein in resistance training individuals, the authors used a model study: in thirty-two male Fischer rats who were randomly assigned to control sedentary, control exercised, whey protein sedentary, and WP exercised groups (n=8/group), half of the rodents (those in the exercise group) were subjected to an interesting resistance training regimen:
"RE consisted of inducing the animals to perform sets of jumps in a circular plastic container with a depth corresponding to 150 % of their body length. Weights were attached to the animal’s chest to promote submersion and the resistance to the exercise. When the rats touched the bottom of the container, they had to jump to emerge from the water to breathe. The RE program consisted of inducing the animals to perform four sets of 10 jumps per day, five times per week for 8 weeks. A one-minute rest interval was included between each set of jumps. Exercise intensity was increased weekly by changing the maximum weight supported by each animal to perform the set of jumps correctly (~25 % of body weight in week 1, ~30 % in week 2, ~ 35 % in week 3, ~40 % in week 4, ~45 % in week 5, ~50 % in week 6, and ~ 55 % in weeks 7 and 8); 55 % of body weight was the greatest weight supported by the rats to perform all jumping sets correctly" (Teixeira. 2016)Now, what is particularly interesting about the study is that the researchers did not add the whey protein to the diet, but simply replaced the regular 14% protein in form of caseinate in the rats' AIN-93M chow with whey protein (still only 14% of the energy).
Why is it important that the scientists replaced the protein source? If Teixeira et al. had simply added extra-whey on top, you could always have argued that the effects they observed would have been the mere result of extra protein, not some special quality (in this case most likely the antioxidant effects) of whey.Against that background, it is quite interesting to see how significant the effect of whey turned out to be... at least in the exercised group, where you can easily see in Figure 1 that the initially identical weights differed significantly at the end of the 8-week study. Since differences occurred only in comparison to the control + exercise group and we don't have total lean and fat mass data, it is, unfortunately, impossible to tell for sure how much if any of the gained weight was, as the previously mentioned SuppVersity reader feared body fat and how much was muscle weight.
|Figure 2: Changes in body weight (%-ages indicate relative weight change from baseline), muscle weight and food intake (%-ages indicate difference between exercise and control group | Teixeira. 2016)|
So, if it's not the "disconcerting news" that whey could make you fat and/or blunt weight loss what is it, then, that the study at hand tells us. Well, I guess there are two answers: Answer (a) is a confirmation of the authors' hypothesis that whey protein has significant antioxidant and anticatabolic effects. Answer (b), on the other hand, is not as favorable for whey protein is (a) as it emphasizes that, without exercise, simply adding whey protein to the diet won't build any extra muscle... speaking of muscle, I've communicated with the authors who confirmed that they "did not evaluate body composition in these rats" (so it's not that they just didn't report it, because it may not be that relevant for their specific study interest), but found "that WP exercised rats showed a better body composition and exercise performance" (private communication); and, what's more, to quantify the last-mentioned effects, will be the goal of follow-up studies.
- Baer, David J., et al. "Whey protein but not soy protein supplementation alters body weight and composition in free-living overweight and obese adults." The Journal of nutrition 141.8 (2011): 1489-1494.
- Chesky, Jeffrey A., and Morris Rockstein. "Life span characteristics in the male Fischer rat." Experimental aging research 2.5 (1976): 399-407.
- Hayes, Alan, and Paul J. Cribb. "Effect of whey protein isolate on strength, body composition and muscle hypertrophy during resistance training." Current Opinion in Clinical Nutrition & Metabolic Care 11.1 (2008): 40-44.
- Teixeira, Kely R., et al. "Whey protein increases muscle weight gain through inhibition of oxidative effects induced by resistance exercise in rats." Nutrition Research (2016).