Weight loss maintenance (WLM) is accompanied by metabolic adjustments that reduce energy expenditure (EE) throughout weight regain and accelerate mass accretion. Previously, our lab demonstrated that regular exercise attenuates weight regain, in part, by increasing EE beyond the cost of exercise. The purpose of this study was to investigate if the benefits of exercise on EE during weight regain are due to the acute effects of a single bout or the adaptations to chronic exercise. We hypothesized that both acute and chronic adaptations would be required to potentiate EE.
For all interventions, obese mice were calorie restricted to induce WLM and subsequently allowed to eat ad libitum to prompt weight regain. To recapitulate training adaptations independent of exercise, we used transgenic mice (mLPL) that overexpress lipoprotein lipase in skeletal muscle (SM). Acute exercise (AE) in wild type (WT) and mLPL mice consisted of a single 3-hour exposure to a running wheel immediately prior to day 1 of weight regain. Metabolic phenotype was assessed using indirect calorimetry. mRNA sequencing was performed on SM and analyzed for Kegg pathway enrichment.
Both AE and mLPL potentiated EE during weight regain compared to controls (p<0.05), but there was no interaction (p>0.05). For AE and mLPL, this increase in EE attenuated weight regain compared to controls (p<0.05), as no differences in energy intake were observed (p>0.05). Transcriptome analysis in SM revealed that WT mice reduced pathways of fat metabolism and increased pathways of carbohydrate metabolism during weight regain compared to WLM (p<0.05). Compared to WT, mLPL enhanced pathways of fat metabolism during WLM and regain (p<0.05).
These observations suggest that both the adaptive and acute response to exercise potentiate EE beyond the cost of an exercise bout during weight regain and are additive when paired together. Additionally, these results indicate that SM fat metabolism may influence EE during weight regain.