BackgroundObesity has reached epidemic proportions in the United States. It is implicated in the development of a variety of chronic disease states and is associated with increased levels of inflammation and oxidative stress. The objective of this study is to examine the effect of Medifast's meal replacement program (MD) on body weight, body composition, and biomarkers of inflammation and oxidative stress among obese individuals following a period of weight loss and weight maintenance compared to a an isocaloric, food-based diet (FB).MethodsThis 40-week randomized, controlled clinical trial included 90 obese adults with a body mass index (BMI) between 30 and 50 kg/m2, randomly assigned to one of two weight loss programs for 16 weeks and then followed for a 24-week period of weight maintenance. The dietary interventions consisted of Medifast's meal replacement program for weight loss and weight maintenance, or a self-selected, isocaloric, food-based meal plan.ResultsWeight loss at 16 weeks was significantly better in the Medifast group (MD) versus the food-based group (FB) (12.3% vs. 6.9%), and while significantly more weight was regained during weight maintenance on MD versus FB, overall greater weight loss was achieved on MD versus FB. Significantly more of the MD participants lost ≥ 5% of their initial weight at week 16 (93% vs. 55%) and week 40 (62% vs. 30%). There was no difference in satiety observed between the two groups during the weight loss phase. Significant improvements in body composition were also observed in MD participants compared to FB at week 16 and week 40. At week 40, both groups experienced improvements in biochemical outcomes and other clinical indicators.ConclusionsOur data suggest that the meal replacement diet plan evaluated was an effective strategy for producing robust initial weight loss and for achieving improvements in a number of health-related parameters during weight maintenance, including inflammation and oxidative stress, two key factors more recently shown to underlie our most common chronic diseases.Trial RegistrationClinicalTrials.gov NCT01011491
A diet using portion-controlled meal replacements yielded significantly greater initial weight loss and less regain after 1 year of maintenance than a standard, self-selected, food-based diet. As PCDs may help obese patients with type 2 diabetes adhere to a weight control program, diabetes educators may consider recommending them as part of a comprehensive approach to weight control.
The effects of a group-oriented contingency on the social and supportive interactions of three preschoolers with autism and their socially competent peers were examined. Children participated in daily manipulative play activities in groups of three (including one target child and two peers). A group reinforcement contingency increased all three target children's social interactions with peers (e.g., share, assistance, and play organizers) but produced few or no corollary supportive exchanges within the playgroups (e.g., one socially competent youngster tells another to "Ask [target child] to share the Lego toys with us"). After a withdrawal of treatment phase in which social interactions decreased to low levels, children were taught to direct supportive comments to other members of their playgroups. Following this brief training, the interdependent group contingency was reinstated to reinforce the share, assistance, and play organizer exchanges between the target children and peers. In addition to interacting with the target children, socially competent youngsters also used supportive prompts to facilitate the social exchanges between their remaining group members. Children's social and supportive interactions decreased and increased again during subsequent baseline and group contingency phases. These results are discussed with regard to the efficacy of group-oriented contingencies and the function of supportive peer behaviors.
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