The literature summarized above suggests that combining exercise and a reduced dietary fat intake should favor spontaneous body weight loss in obese individuals. In obese women, this combination was found to induce a mean decrease in body weight of 16% that was associated with a normalization of the metabolic risk profile (7). In a more recent study, we used the exercise-low fat diet combination as a follow-up of a treatment of obesity consisting of drug therapy and low calorie diet (56). In this context, exercise and low fat diet accentuated the fat loss induced by the first phase of treatment up to a mean cumulative weight loss of 14% and 10% of initial values in men and women, respectively. In addition, the exercise-low fat diet follow-up was again associated with a normalization of the metabolic risk profile. As shown in Table 12.4, these observations are consistent with a recent study demonstrating that the regular physical activity and adherence to a low fat dietary regimen are the main features of the lifestyle of ex-obese individuals maintaining a large weight loss on a long-term basis (57).
Even if the combination of exercise and low fat diet can induce a considerable body energy deficit under free-living conditions, it is likely that adipose tissue-related regulatory factors of energy and fat balance will over time favor the restabilization of body weight. These factors, which are associated with resistance to further loss of weight in the reduced-obese individual, are probably the same ones that promote the achievement of a new body weight plateau in the context of overfeeding. Thus, as discussed above, the decrease in sympathetic nervous system activity and in plasma FFA, leptin, and insulin probably contributes to resistance to losing more fat after having experienced success with exercise and a low fat diet. In this context of increased
Table 12.4 Characteristics of individuals maintaining a weight loss of at least 30 pounds (13.6kg) for at least one year
Body weight loss 30.1 kg
Duration of maintenance 5.7 years
Relative fat intake 25% of total energy intake
Physical activity participation" 11 847 kJ/week including strenuous physical activities. Adapted from McGuire et al. (57).
vulnerability towards a fattening lifestyle, the ex-obese person obviously must maintain his/her new exercise-low fat diet lifestyle to prevent further weight regain.
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