Overweight and obesity result from a complex interaction of behavioral, environmental, and genetic factors. The present study reports on the efficacy of a community-based weight control program in 31 overweight and obese adults. TrymGym is a multi-dimensional lifestyle behavior change program for improving both diet and physical activity (PA) related behavior with education and cognitive behavioral training. The program was evaluated using nutritional, physiological, and physical activity-related psychological factors before and after the 12 week program. Paired sample t-tests were conducted to identify significant changes. Body weight (BW) and diastolic blood pressure decreased by 3.6 and 6.4% respectively in completers of the study. Waist and hip circumferences decreased by 4.1 and 5.7% respectively. Caloric intake decreased from 1994+/-146 at baseline to 1768+/-144 in completers of the study. There was also a significant 5.2% decrease in the percentage of calories derived from fat and a 4% increase in percent of calories from protein. Although intake of vitamin C was increased at the end of the study, intake of several other micronutrients at baseline did not meet Dietary Reference Intake recommendations and were further compromised at week 12. Despite a trend toward increased participation in leisure-time and strenuous PA there was a decrease in behavioral intention to participate in future PA. Overall, this community-based weight control program was effective in fostering a significant improvement in BW, anthropometric measurements, participation in PA, and nutritional intake.