Background: As obesity increases the risk of chronic diseases. Many countries have developed group-based programs for weight loss and a meta-analysis of diet and physical activity weight loss interventions which have shown that they are effective in promoting weight loss.

Objective: To study the effects of intensive lifestyle intervention combined with competition groups on body mass index.

Materials and Methods: The 120 officers at the Airports of Thailand Public Company Limited (AOT) joined this program for 3 months in the year 2017. The authors allocated the samples into small divisions to enable competitions in LINE groups. During the 3-month program, we provided education, assigned activities, and reported step counts. The parameters studied were body weight, BMI, waist circumference, % Fat, % visceral fat and % muscle. Physical fitness was assessed by recording hand-grip power, number of sit-ups completed in 1 minute, and flexibility before and after the 3-month program.

Results: Seventy-three samples completed the program. Significant reductions were achieved in body weight (75.6 kg to 71.7 kg), BMI (27.3 to 26.0 kg/m2), waist circumference (90.3 to 83.5 cm) % fat (31.1 to 29.6%), and % visceral fat (11.0 to 9.4%), and a significant increase in the % muscle (27.1 to 27.6%) was also found. Physical fitness improved, including hand-grip power, number of sit-ups completed in 1 minute, and flexibility. There were no significant differences between these changes in male and female groups except that % fat and % muscle improved significantly more in the male group.

Conclusion: A combination of lifestyle intervention and competitions in LINE groups achieved weight loss and enhanced physical fitness.

Keywords: Weight loss, Physical fitness, Line group, Competition, Lifestyle intervention, Group-based program