Dietary Whey Protein Decreases Food Intake and Body Fat in Rats

Abstract

We investigated the effects of dietary whey protein on food intake, body fat, and body weight gain in rats. Adult (11–12 week) male Sprague–Dawley rats were divided into three dietary treatment groups for a 10-week study: control. Whey protein (HP-W), or high-protein content control (HP-S). Albumin was used as the basic protein source for all three diets. HP-W and HP-S diets contained an additional 24% (wt/wt) whey or isoflavone-free soy protein, respectively. Food intake, body weight, body fat, respiratory quotient (RQ), plasma cholecystokinin (CCK), glucagon like peptide-1 (GLP-1), peptide YY (PYY), and leptin were measured during and/or at the end of the study. The results showed that body fat and body weight gain were lower (P < 0.05) at the end of study in rats fed HP-W or HP-S vs. control diet. The cumulative food intake measured over the 10-week study period was lower in the HP-W vs. control and HP-S groups (P < 0.01). Further, HP-W fed rats exhibited lower N2 free RQ values than did control and HP-S groups (P < 0.01). Plasma concentrations of total GLP-1 were higher in HP-W and HP-S vs. control group (P < 0.05), whereas plasma CCK, PYY, and leptin did not differ among the three groups. In conclusion, although dietary HP-W and HP-S each decrease body fat accumulation and body weight gain, the mechanism(s) involved appear to be different. HP-S fed rats exhibit increased fat oxidation, whereas HP-W fed rats show decreased food intake and increased fat oxidation, which may contribute to the effects of whey protein on body fat.

Bioactivity in Whey Proteins Influencing Energy Balance

“…The suggestion that whey proteins induce satiety has been further confirmed in mice by showing that whey protein isolate providing 30% energy increased intermeal interval (satiety) compared to soy protein during the 7 day period of the study [7]. Similar findings have been reported from a long term study lasting 10 weeks [8]. These data are consistent with the findings from human studies that whey proteins reduce food intake by inducing satiety in the lean state.…”

“…In the studies mentioned above, except for the latter, the observed effects of whey protein on lipid metabolism were shown relative to casein. Interestingly, in contrast, soy proteins at 24% (wt/wt) in the diet of rats had a similar effect on body weight and abdominal fat as whey proteins [8]. This data could be interpreted to suggest that whey protein effects on lipid metabolism are detectable only when casein is used as the control protein, or that the lack of an effect on lipid metabolism in comparison to soy might be due to the fact that the above study assessed dietary protein effects on lean rats as oppose to obese rodents, which are known to have a higher body weight and body fat content and thus, are likely to be more susceptible to whey protein effects on lipid metabolism.…”

“…Similar data have been obtained from rodent studies. Zhou et al showed that the reduction in food intake in lean rats on a diet supplemented with 24% (wt/wt) whey protein concentrate, is accompanied by an increased GLP-1 level in the plasma [8]. Given that both α-lactalbumin and β-lactoglobulin have been shown to influence food (energy) intake, it would be interesting to find out whether these proteins are responsible for the observed changes in hormone levels detected in human and rodent studies.…”

Factors affecting circulating levels of peptide YY in humans: a comprehensive review

“…Two studies in human subjects have reported no differences in the PYY response to a whey v. casein protein meal (105) or whey v. both pea protein hydrolysate and a combined casein/whey milk protein (80 % casein, 20 % whey) (106) . Further, a 10-week feeding study in rats found no differences in plasma PYY levels between whey and soya protein diets (107) . Conversely, PYY mRNA was down-regulated in rats following a lifetime of a high-whey diet v. high-casein or high-soya diets (108) .…”

Desenvolvimento, caracterização e análise sensorial de formulações alimentares com proteínas do soro de leite ou albumina para crianças

“…Dentre as propriedades funcionais desses peptídios, pode-se citar as ações antihipertensiva (MORAIS et al, 2014;, hipocolesterolêmica, imunomoduladora (SINHA et al, 2007), antioxidante (SINHA et al, 2007;SILVESTRE et al, 2013), inibidora do apetite e redutora de gordura corporal (ZHOU et al, 2011;SOUSA et al, 2012).…”