Regular exercise attenuates the metabolic drive to regain weight after long-term weight loss

Abstract

Brown IE, Hill JO. Regular exercise attenuates the metabolic drive to regain weight after long-term weight loss. Am J Physiol Regul Integr Comp Physiol 297: R793-R802, 2009. First published July 8, 2009 doi:10.1152/ajpregu.00192.2009.-Weight loss is accompanied by several metabolic adaptations that work together to promote rapid, efficient regain. We employed a rodent model of regain to examine the effects of a regular bout of treadmill exercise on these adaptations. Obesity was induced in obesity-prone rats with 16 wk of high-fat feeding and limited physical activity. Obese rats were then weight reduced (ϳ14% of body wt) with a calorie-restricted, low-fat diet and maintained at that reduced weight for 8 wk by providing limited provisions of the diet with (EX) or without (SED) a daily bout of treadmill exercise (15 m/min, 30 min/day, 6 days/wk). Weight regain, energy balance, fuel utilization, adipocyte cellularity, and humoral signals of adiposity were monitored during eight subsequent weeks of ad libitum feeding while the rats maintained their respective regimens of physical activity. Regular exercise decreased the rate of regain early in relapse and lowered the defended body weight. During weight maintenance, regular exercise reduced the biological drive to eat so that it came closer to matching the suppressed level of energy expenditure. The diurnal extremes in fuel preference observed in weight-reduced rats were blunted, since exercise promoted the oxidation of fat during periods of feeding (dark cycle) and promoted the oxidation of carbohydrate (CHO) later in the day during periods of deprivation (light cycle) . At the end of relapse, exercise reestablished the homeostatic steady state between intake and expenditure to defend a lower body weight. Compared with SED rats, relapsed EX rats exhibited a reduced turnover of energy, a lower 24-h oxidation of CHO, fewer adipocytes in abdominal fat pads, and peripheral signals that overestimated their adiposity. These observations indicate that regimented exercise altered several metabolic adaptations to weight reduction in a manner that would coordinately attenuate the propensity to regain lost weight. fat oxidation; energy balance; indirect calorimetry; postobese; adipocyte cellularity WEIGHT REGAIN AFTER WEIGHT loss has been repeatedly shown in both obese animals (3, 4, 6, 9, 21-23, 25, 26, 30) and humans (14,18,32,42,43). A meta-analysis of a large number of U.S. weight loss studies summarized the propensity to regain after a wide variety of weight loss programs (1). Not only does lost weight tend to return, but the rate of return is highest immediately after the cessation of the structured weight loss program. Over 35% of the lost weight returns in the first year, and the majority is gained back within five years. Most people view their weight loss program as a transient change in their lifestyle and dietary habits or have difficulty in sustaining the changes that they have made to lose the weight (7, 11).The proposed reasons for the high rate of weight rega...

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Biology's response to dieting: the impetus for weight regain

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Measurement and Physiological Relevance of the Maximal Lipid Oxidation Rate During Exercise (LIPOXmax)

“…However the effects of exercise as a weight reducing procedure have been considered during many years as rather limited and almost negligible. It is beyond any doubt that regular exercise attenuates the metabolic drive to regain weight after long-term weight loss (MacLean et al, 2009). The interest of physical activity was thus mostly to prevent weight gain, to improve stabilization after slimming, and to reduce obesity-related co-morbidities but not to reduce weight by its own (Jakicic & Otto, 2005Duclos et al, 2010).…”