When you stop working out, you may experience weight gain for several reasons.

First, without regular physical activity, your body may burn fewer calories, leading to an increase in body fat. Physical activity helps increase your metabolism and burn calories, so when you stop working out, your body may not be able to burn as many calories, leading to weight gain.

Second, without regular exercise, you may lose muscle mass. Muscle is an active tissue that burns calories, so when you lose muscle mass, your body may burn fewer calories, leading to weight gain. In addition, losing muscle mass can decrease your resting metabolic rate, which is the number of calories your body burns at rest, further contributing to weight gain.

Third, when you stop working out, you may experience changes in your appetite and eating habits. Without the structure and routine of a regular exercise program, you may be more likely to eat more or make poor food choices, leading to weight gain. In addition, without the physical and mental benefits of regular exercise, you may be more likely to experience stress, boredom, or emotional eating, which can also contribute to weight gain.

Overall, when you stop working out, you may experience weight gain due to a decrease in calorie burning, loss of muscle mass, and changes in appetite and eating habits. To prevent weight gain when you stop working out, it is important to maintain a healthy diet, engage in regular physical activity, and manage stress and emotional eating.