The main reasons for gaining weight while working out include:
- Gaining muscle mass, which weighs more than fat and can make the scale go up even as body composition improves.
- Water retention caused by muscle inflammation and repair, especially when starting strength training or a new workout routine.
- Increased glycogen storage in muscles, which binds to water and can temporarily add weight.
- Potentially eating more calories than burned, sometimes due to increased appetite from exercise.
- Insufficient rest or high stress levels raising cortisol, which can cause fat retention.
- Underlying health issues like thyroid problems or insulin resistance that affect metabolism.
This weight gain is often temporary and a sign the body is adapting, building muscle, and repairing itself. It doesn't necessarily mean fat gain, and over time the body adjusts, often leading to fat loss and improved fitness despite the temporary upward shift on the scale.
