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-   -   Whey Protein but Not Soy Protein Supplementation Alters Body Weight and Composition (http://www.catalystathletics.com/forum/showthread.php?t=6250)

William McAlpine 06-29-2011 05:25 AM

Whey Protein but Not Soy Protein Supplementation Alters Body Weight and Composition
In Obese Adults

2011 American Society for Nutrition



A double-blind, randomized clinical trial was conducted to determine the effect of consumption of supplemental whey protein (WP), soy protein (SP), and an isoenergetic amount of carbohydrate (CHO) on body weight and composition in free-living overweight and obese but otherwise healthy participants. Ninety overweight and obese participants were randomly assigned to 1 of 3 treatment groups for 23 wk: 1) WP; 2) SP (each providing ~56 g/d of protein and 1670 kJ/d); or 3) an isoenergetic amount of CHO. Supplements were consumed as a beverage twice daily. Participants were provided no dietary advice and continued to consume their free-choice diets. Participants’ body weight and composition data were obtained monthly. Dietary intake was determined by 24-h dietary recalls collected every 10 d. After 23 wk, body weight and composition did not differ between the groups consuming the SP and WP or between SP and CHO; however, body weight and fat mass of the group consuming the WP were lower by 1.8 kg (P < 0.006) and 2.3 kg (P < 0.005), respectively, than the group consuming CHO. Lean body mass did not differ among any of the groups. Waist circumference was smaller in the participants consuming WP than in the other groups (P < 0.05). Fasting ghrelin was lower in participants consuming WP compared with SP or CHO. Through yet-unknown mechanisms, different sources of dietary protein may differentially facilitate weight loss and affect body composition. Dietary recommendations, especially those that emphasize the role of dietary protein in facilitating weight change, should also address the demonstrated clinical potential of supplemental WP.

William McAlpine 06-30-2011 09:09 AM

Some snips from the paper:


Mean energy intake (including supplements) was 9060 + or - 560, 9140 + or - 510, and 940 + or - 460 kJ/d for the CHO, WP and SP groups, respectively and did not differ among treatment groups.

Energy and macronutrient intakes were higher for men than for women (P<.0001), with no detectable effect of treatment on changes in energy, protein, carbohydrate, or fat intake during the course of the intervention. Between the initial and final recall, there was a decrease in carbohydrate intake in the group consuming the WP supplement (P<.04).

Additionally, consuming WP resulted in a significantly smaller waist circumference compared with the group consuming supplemental CHO. This finding is important, because the amount of intra-abdominal adipose tissue is more significantly correlated with metabolic complications in obese individuals than in subcutaneous fat.

Circulating IGF-1 concentrations were higher in the group consuming the SP supplement than in the groups supplemented with WP or CHO, whereas IGFBP-3 concentrations were lower in the group supplemented with WP than in the other 2 groups. THE IGFBP-1 concentration was not affected by treatment. T3 uptake was lower in the group supplemented with SP; the group supplemented with CHO did not differ from either protein group. Free T4 concentrations were lower in the groups supplemented with WP and CHO than in the group supplemented with WP and CHO than in the group supplemented with SP.

The authors did not suggest a mechanism why WP would be superior to weight loss. Any ideas?

Steven Low 07-01-2011 11:39 AM

Well, whey is primarily derived from animal milks.

Soy is from plants.

Since we evolved as meat eaters I don't think it would be a stretch to say that we absorb and translate energy and other signalling more from animal type proteins better than plant protein.

I don't know the particular amino acid compositions of whey and soy respectively, but I do know that whey contains at least a significant percentage of BCAAs which has been shown to have favorable effects during exercise and metabolism in general

Blair Lowe 07-01-2011 03:00 PM

Steve I recently look up the amino acid values of whey concentrate, egg, brown rice, spirulina, hemp, and soy for a thread over on gymnasticbodies.

Whey has a far higher amount of amino acids per gram of protein than soy does. I found data for some form of sprouted brown rice and some other brown rice proteins.

Whey, egg were pretty close. Soy and hemp were pretty close though spirulina was superior to them. Whey and egg were quite a bit higher than soy. That sprouted brown rice was on par with whey and egg according to the data I found.

Steven Low 07-02-2011 10:55 AM

Makes sense since animals are more dense sources of protein anyway (e.g. muscle) and it would make sense that nutrition from such animals would be geared towards their growth

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