Exercise and Dairy Protein have Distinct Effects on Indices of Liver and Systemic Lipid Metabolism.

OBJECTIVE: This study aimed to explore the individual and combined effects of skim milk powder (SMP) and exercise on indices of systemic and liver lipid metabolism in male obese rats. METHODS: Rats were fed a high-fat (~ 40% kcal from fat), high-sugar diet for 8 weeks. At 12 weeks of age, rats were assigned to one of four weight-matched, isocaloric, high-fat, high-sugar groups for 6 weeks: (1) casein-sedentary, (2) casein-exercise, (3) SMP-sedentary, and (4) SMP-exercise. Nonfat SMP or casein was the sole protein source in the dairy and control casein diets, respectively. Exercise training occurred 5 d/wk for 60 minutes on a motorized treadmill. Whole-body metabolism was assessed by a Comprehensive Lab Animal Monitoring System. Lipidomics, Western blot, and polymerase chain reaction were used to assess markers of hepatic lipid metabolism. RESULTS: Exercise, but not SMP, altered the fatty acid composition of liver triglycerides, reduced indices of lipogenesis, and increased expression of genes linked to oxidative metabolism, in conjunction with increases in whole-body fat oxidation. SMP and exercise reduced plasma triglycerides in an additive manner. CONCLUSIONS: These findings provide evidence that SMP and exercise exert distinct effects on whole-body and hepatic carbohydrate and lipid metabolism and that they could work in a synergistic manner to reduce serum triglyceride concentrations.

Distinct Gut Microbiota and Serum Metabolites in Response to Weight Loss Induced by Either Dairy or Exercise in a Rodent Model of Obesity.

Energy imbalance is a primary cause of obesity. While the classical approach to attenuate weight gain includes an increase in energy expenditure through exercise, dietary manipulation such as the inclusion of dairy products has also been proven effective. In the present study, we explored the potential mechanisms by which dairy and exercise attenuate weight gain in diet-induced obese rats. Male Sprague-Dawley rats were fed a high fat, high-sugar (HFHS) diet to induce obesity for 8 weeks. Rats were then further grouped into either control (HFHS + casein) or dairy diet (HFHS + nonfat skim milk) with and without treadmill exercise for 6 weeks. Serum and fresh fecal samples were collected for gut microbiota, serum metabolomics, and metallomics analysis. Diet and exercise resulted in distinct separation in both gut microbiota and serum metabolite profiles. Most intriguingly, obesogenic bacteria including Desulfovibrio and Oribacterium were reduced, and bioactive molecules such as mannose and arginine were significantly increased in the dairy group. Correlations of at least six bacterial genera with serum metal ions and metabolites were also found. Results reveal distinct impacts of dairy and exercise on the gut microbiota and in the modulation of circulating metabolites with the former primarily responsible for driving microbial alterations known to attenuate weight gain.

Prior Endurance Training Enhances Beta-Adrenergic Signaling in Epidydimal Adipose from Mice Fed a High-Fat Diet.

OBJECTIVE: Adipose tissue beta-adrenergic signaling is attenuated in obesity and insulin resistance. It has been previously demonstrated that prior exercise training protects against short-term, high-fat diet (HFD)-induced weight gain and glucose intolerance. This study aimed to determine whether prior exercise training results in altered beta-adrenergic and lipolytic signaling in adipose tissue when challenged with a HFD. METHODS: Male C57BL/6J mice underwent 4 weeks of treadmill training (1 h/d, 5 d/wk). Twenty-four hours after the final bout of exercise, mice were fed a HFD (60% kcal lard) for 4 days. RESULTS: Serum fatty acids, beta-adrenergic signaling (phosphorylated ERK, hormone-sensitive lipase, and p38), and perilipin 1 content were greater in epididymal white adipose tissue (eWAT) from previously trained mice. These changes were not evident in eWAT from trained mice prior to the HFD and were not secondary to alterations in insulin responsiveness or catecholamine concentrations. CL 316,243-mediated increases in hormone-sensitive lipase phosphorylation and fatty acid accumulation in the media were greater in adipose tissue explants from previously trained mice fed a HFD. CONCLUSIONS: These findings suggest that previous training increases adipose tissue beta-adrenergic responsiveness to a short-term HFD. This may help to explain the protective effect of prior exercise training against the deleterious effects of a HFD.

Dairy Attenuates Weight Gain to a Similar Extent as Exercise in Rats Fed a High-Fat, High-Sugar Diet.

OBJECTIVE: To compare the individual and combined effects of dairy and endurance exercise training in reducing weight gain and adiposity in a rodent model of diet-induced obesity. METHODS: An 8-week feeding intervention of a high-fat, high-sugar diet was used to induce obesity in male Sprague-Dawley rats. Rats were then assigned to one of four groups for 6 weeks: (1) casein sedentary (casein-S), (2) casein exercise (casein-E), (3) dairy sedentary (dairy-S), and (4) dairy exercise (dairy-E). Rats were exercise trained by treadmill running 5 d/wk. RESULTS: Dairy-E prevented weight gain to a greater extent than either dairy or exercise alone. Adipose tissue and liver mass were reduced to a similar extent in dairy-S, casein-E, and dairy-E groups. Differences in weight gain were not explained by food intake or total energy expenditure. The total amount of lipid excreted was greater in the dairy-S compared to casein-S and dairy-E groups. CONCLUSIONS: This study provides evidence that dairy limits weight gain to a similar extent as exercise training and the combined effects are greater than either intervention alone. While exercise training reduces weight gain through increases in energy expenditure, dairy appears to increase lipid excretion in the feces.