Regular exercise counteracts the propensity to regain weight following weight loss
by Steig, Amy Jean, Ph.D., UNIVERSITY OF COLORADO HEALTH SCIENCES CENTER, 2009, 129 pages; 3375576

Abstract:

Weight loss is associated with a number of metabolic adaptations that promote weight regain. Exercise has proven to be a critical component of the prevention of weight regain following weight loss. It is unclear, however, whether the shift in metabolism caused by exercise is simply a consequence of the reduced energy imbalance, or whether exercise imparts additional adaptations in the periphery that increases the oxidation of dietary fat.

In a rodent paradigm of weight regain, obesity-prone rats were matured in an obesigenic environment and then calorically restricted for eight weeks (25% fat diet) with (WR-EX) and without (WR-Sed) regular exercise (1h/day, 6d/wk, 15m/min). A 24-hour dietary tracer (14C-palmitate/ 14C-oleate) was used in conjunction with indirect calorimetry to assess the oxidation of dietary fats in WR-EX and WR-Sed rats, while in energy balance; and in relapsing rats, with (Rel-EX) or without exercise (Rel-Sed), while feeding ad libitum for one day. An additional group of sedentary, relapsing rats were given enough food to match the energy gap found in REL-EX rats (gap-matched, GM) in order to assess the peripheral effects of exercise, given the same caloric excess.

Regular exercise significantly decreased energy intake by 28% on the first day of relapse (Rel-Sed vs. Rel-EX; p<0.001). Regular exercise increased 24-hour dietary fat oxidation in both the weight reduced (WR-EX vs. WR-Sed; p<0.05) and relapsing (Rel-EX vs Rel-Sed; p<0.05) rats. Despite consuming the same caloric excess as GM rats, the oxidation of dietary fat in the REL-EX rats was 21% higher (p<0.05). Gene expression analysis of the skeletal muscle demonstrates that regular exercise increases the expression of key genes that promote fatty acid uptake (LPL, CD-36, FABP3) and oxidation (PGC1 a, Sirtuin1, and Adiponectin Receptor2, PDK4).

Regular exercise increased the oxidation of dietary fat, an effect that is due to adaptations in the periphery. Specifically, regular exercise increases the ability to take-up and oxidize fats in the skeletal muscle. These peripheral adaptations result in increased oxidation of dietary fat on the first day of relapse.

 
AdviserPaul MacLean
SchoolUNIVERSITY OF COLORADO HEALTH SCIENCES CENTER
SourceDAI/B 70-09, p. , Oct 2009
Source TypeDissertation
SubjectsNutrition; Kinesiology
Publication Number3375576
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