Excessive masturbation does not cause weight gain, according to scientific evidence. A combination of poor diet, lack of exercise, and genetics usually causes weight gain. Masturbation, when done in moderation, is a natural and healthy sexual activity that does not directly affect a person's weight. However, excessive masturbation can lead to a sedentary lifestyle, contributing to weight gain if combined with unhealthy eating habits and lack of physical activity. Maintaining a healthy lifestyle and practicing moderation is important to avoid any potential negative effects of excessive masturbation.