A Structured Diet and Exercise Program Promotes Favorable Changes in Weight Loss, Body Composition, and Weight Maintenance

Background A number of diet and exercise programs purport to help promote and maintain weight loss. However, few studies have compared the efficacy of different methods. Objective To determine whether adherence to a meal-replacement–based diet program (MRP) with encouragement to increase physical activity is as effective as following a more structured meal-plan–based diet and supervised exercise program (SDE) in sedentary obese women. Design Randomized comparative effectiveness trial. Participants/setting From July 2007 to October 2008, 90 obese and apparently healthy women completed a 10-week university-based weight loss trial while 77 women from this cohort also completed a 24-week weight maintenance phase. Intervention Participants were matched and randomized to participate in an MRP or SDE program. Main outcome measures Weight loss, health, and fitness-related data were assessed at 0 and 10 weeks on all subjects as well as at 14, 22, and 34 weeks on participants who completed the weight maintenance phase. Statistical analyses performed Data were analyzed by multivariate analysis of variance for repeated measures. Results During the 10-week weight loss phase, moderate and vigorous physical activity levels were significantly higher in the SDE group with no differences observed between groups in daily energy intake. The SDE group lost more weight (−3.1±3.7 vs −1.6±2.5 kg; P=0.03); fat mass (−2.3±3.5 vs −0.9±1.6 kg; P=0.02); centimeters from the hips (−4.6±7 vs −0.2±6 cm; P=0.002) and waist (−2.9±6 vs −0.6±5 cm; P=0.05); and, experienced a greater increase in peak aerobic capacity than participants in the MRP group. During the 24-week maintenance phase, participants in the SDE group maintained greater moderate and vigorous physical activity levels, weight loss, fat loss, and saw greater improvement in maximal aerobic capacity and strength. Conclusions In sedentary and obese women, an SDE-based program appears to be more efficacious in promoting and maintaining weight loss and improvements in markers of health and fitness compared to an MRP type program with encouragement to increase physical activity. Obesity has become a worldwide epidemic, with an estimated 1.2 billion people overweight and at least 300 million people considered obese ( [1], [2], [3] and [4]). Obesity is associated with increased risk of hypertension, diabetes mellitus, dyslipidemia, and liver disease ( [1], [4] and [5]). It is also associated with increased morbidity, mortality, and has a significant socioeconomic effect ( [5], [6], [7], [8], [9], [10] and [11]). Whereas obesity had been thought to simply be related to an imbalance between energy intake and expenditure, more recent research has indicated that genetic, physiological, psychological, socioeconomic, cultural, and behavioral factors also play a role in the etiology of obesity in various populations ( [1], [2], [3], [4], [7] and [12]). For this reason, the prevention, treatment, and management of obesity are complex and require multifaceted interventions ( [4] and [7]). A number of studies have reported that different types of diet, exercise, and/or behavioral interventions can promote weight loss. For example, studies have shown that reducing energy intake ( [13], [14] and [15]), altering macronutrient intake ( [16], [17], [18] and [19]), increasing dietary fiber intake ( [20], [21] and [22]), use of ready-to-eat (RTE) meals as meal replacements ( [23], [24], [25], [26], [27] and [28]), and increasing dietary availability of some nutrients can promote weight loss to varying degrees ( [17], [29], [30], [31], [32] and [33]). It is also known that increasing physical activity (PA) and energy expenditure can help promote and/or maintain weight loss ( [25], [34] and [35]) and that the mode of exercise employed (eg, walking or resistance training) may have differential effects ( [36], [37], [38] and [39]). In addition, a number of behavioral interventions (eg, nutrition education, counseling, provision of meal plans, use of prepared meals, monitoring of results, social support, and degree of supervision) can influence the success of weight loss and maintenance programs ( [7], [25], [40] and [41]). However, few studies have compared one strategy to another to assess the efficacy of different diet, exercise, and/or behavioral intervention strategies on weight loss and management. Given the high costs of treating obesity and weight loss program interventions, it has become increasingly important to conduct comparative effectiveness trials on weight loss strategies and commercial programs so informed decisions can be made regarding the efficacy, safety, and value of these programs ( [28] and [42]). The purpose of this study was to determine whether adherence to an RTE meal-replacement–based diet that included additional dietary recommendations and encouraged an increase in physical activity is as effective as following a more structured diet plan and supervised exercise program. It was hypothesized that both groups would experience beneficial changes in body mass, body composition, and markers of health. However, participants following the more structured diet and supervised exercise program would experience more favorable results.