|If you want weight loss support, chose the "Wheytloss Wonder" whey concentrate over the allegedly "healthy plant proteins" in soy isolates - if your physiology works anyway similar to the one of the study subjects you won't regret it - promise!|
Based on the existing evidence of the weight loss benefits of high(er) protein diets, the Iranian scientists hypothesized that supplemental preloads of whey protein concentrate (WPI) and soy protein isolate (SPI) would decrease appetite, caloric intake, anthropometry, and alter the body composition of healthy overweight and obese men in free living conditions.
To test this hypothesis, we supplemented free living overweight and obese men with WPC and SPI 30 min before their ad libitum afternoon meals, and monitored each subject’s appetite, calorie intake, anthropometry, and body composition.
Using a monthly bulletin to advertise, volunteer employees of a power plant in Karaj city were recruited to participate in the study. Inclusion criteria included: no cigarette smoking and/or alcohol consumption, no medication and/or supplement usage, no high amounts of caffeine consumption (>250-300 mg/d), no history of diseases or clinical problems that increase oxidative stress (injuries or burns), no allergy to soy/cow's milk, and no severe weight changes within the last three months. Exclusion criteria included any changes in physical activities (PA), diets, and a compliance of 70% or lower for consumption of treatment beverages.
This is a randomized, controlled trial, no epidemiological "healthy plant protein guesswork"
At the first visit, eligible participants were randomly assigned to either the WPC or SPI (26 in each) group, using a convenience allocation. Individuals were instructed to deliver empty sachets in exchange for full ones at visits 2 through 12, in order to calculate compliance.
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"Preload proteins included 80% WPC (DMV, Netherlands) and 90% SPI (Red Crown, China), with similar color and texture. Sachets contained 67.5 g WPC and 60 g SPI (54 g effective compound as a protein / sachet).Calorie contents of WPC and SPI sachets were 261.8 Kcal and 216 Kcal, respectively. They were closely matched for taste with strawberry flavor and sucralose (Vita Sweet, China) (0.2 gr and 0.1 gr in each sachet respectively), as a no-energy sweetener since sucralose is not metabolized in the body and has no effect on blood glucose or insulin secretion." (Tahavorgar. 2014)After packing 4368 similar sachets, they were numbered 1- 84. The numbers were randomly divided into groups A and B (SPI and WPC, respectively) and kept by the executive director of research until study commencement.
One of the strenghts of the study is the fact that dietary intake and physical activity were closely monitored. If the subjects didn't lie about their food intake and activity levels the results of the study at hand are thus highly accurate. Unfortunately, the same cannot be said of the relatively unreliable body fat measurements that were conducted with a body fat monitor by Jawon Medical.The consumption of the protein shakes (65 gr WPC or 60 gr SPI that was dissolved in 500 ml water) 30 min before the ad libitum dinner (late afternoon) lead to significant increases of the total protein intake in both groups, with a slightly higher total protein intake of 33.5% of the total energy intake (vs. 28.7%) in the whey vs. soy group. No wonder that the mean changes in appetite (p=0.032), CI (p=0.045), anthropometry (body weight (BW) (p=0.008), body mass index (BMI) (p=0.006), and waist circumference (WC), body composition (body fat mass (BFM) and lean muscle (LM) were significant in both groups.
|Figure 1: Changes in appetite, calorie intake and body composition during the 12-week study (Tahavorgar. 2014)|
- Tahavorgar, Atefeh, et al. "Whey protein preloads are more beneficial than soy protein preloads in regulating appetite, calorie intake, anthropometry, and body composition of overweight and obese men." Nutrition Research (2014).