F-61 Thematic Poster - Energy Balance and Weight Control Friday, June 3, 2016, 3:15 PM - 5:15 PM Room: 110
Energy restriction (ER) reduces body weight (BW) and adiposity, but is often less than expected due to hypometabolism produced by reductions in lean body mass (LBM). A comparable energy deficit created by combining ER and exercise energy expenditure (EE) has been shown to attenuate the reduction in EE produced by ER. Continuous moderate-intensity training (MIT) is commonly used to sustain energy balance or expedite weight loss, but high-intensity interval training (HIIT) may produce greater results.
PURPOSE: The purpose of this investigation was to determine if HIIT preserves LBM and improves energy metabolism to a greater extent than MIT in the presence of ER.
METHODS: Thirty-two 5-wk old male C57BL/6J mice were placed on a 45% kcal high-fat diet (HFD) for 11 weeks (ad libitum). Mice were then randomized to 4 groups for 14 weeks: 1) HFD (n = 8; remain on HFD); 2) HFD with 25% ER (n = 8); 3) HFD with 25% energy deficit induced by 12.5% ER and 12.5% EE through HIIT (n = 8); and 4) HFD with 12.5% energy deficit induced by 12.5% ER and 12.5% EE through MIT. HIIT consisted of 9-12 intervals of 2.5-minutes of treadmill running at 0.18-0.30 m/s with 1 minute of passive recovery between intervals. MIT consisted of 35-50 minutes of continuous treadmill running at 0.13-0.21 m/s. Body composition was assessed by Quantitative Magnetic Resonance (QMR) and resting energy expenditure (REE) by indirect calorimetry. Glucose tolerance tests were performed on all groups at 1.0 g/kg BW (i.p.), while insulin tolerance tests were performed at 0.75 mU/g BW (i.p.).
RESULTS: HFD increased BW from 20.2±0.2 to 38.8±0.8 g (92.3% increase in BW). REE was 11.2% lower in the ER group compared to Control (73.0±1.7 to 64.8±1.6 kJ/hr LBM, p<0.05). HIIT, but not MIT, preserved LBM and rescued ER-mediated reductions in REE. The increase in LBM was associated with improvements in glucose tolerance and insulin sensitivity.
CONCLUSION: Twenty-five percent ER produced reductions in LBM and REE, whereas HIIT preserved LBM, increased REE and improved glucose tolerance and insulin sensitivity. These results suggest that HIIT may produce a hypermetabolic state in the presence of ER, which could lead to long-term success in weight loss interventions. Supported by UAB Department of Human Studies Pilot Award.