Numbers of obese and overweight people continue to grow in Germany as they do worldwide. Men are affected more often but do less about it and few weight loss services attract men in particular. To evaluate the effectiveness of a men-only weight loss program, Football Fans in Training (FFIT), delivered by football clubs in the German Bundesliga, we did a non-randomized trial with a waiting list control group. Participants' data were collected between January 2017 and July 2018. FFIT is a 12-week, group-based, weight loss program and was delivered in stadia and facilities of 15 professional German Bundesliga clubs. Inclusion criteria were age 35-65 years, BMI ≥ 28 and waist circumference ≥100 cm. Clubs recruited participants through Social Media, E-Mail and match day advertisement. 477 German male football fans were allocated to the intervention group by order of registration date at their respective clubs. 84 participants on waiting list were allocated to the control group. Primary outcome was mean difference in weight loss with treatment condition over time as independent variable. We performed a multilevel mixed-effects linear regression analysis. Results were based on Intention-to-treat (ITT) analysis with Multiple Imputation. After 12 weeks, the mean weight loss of the intervention group adjusted for club, course and participants' age was 6.24 kg (95% CI 5.82 to 6.66) against 0.50 kg (-0.47 to 1.49) in the comparison group (p < 0.001). The results indicate that Football Fans in Training effectively helped German men to reduce their weight and waist circumference.