1. Reduce fat: You may lose body fat during fitness, and muscle gain and fat loss may cancel each other out, resulting in no obvious change in weight. In the process of reducing fat, your body will lose some fat, and muscle growth may fill these lost fat spaces, thus maintaining the stability of weight.

2. Diet: If your diet is not well controlled and your calories are not enough, then your weight may not increase significantly. At the same time, if your nutritional intake is not balanced, it may also affect the change of weight.

3. Training: Your training plan may have reached a plateau, and you need more frequent or intense training to further increase your muscle mass. In addition, if your training plan is too simple and you don't fully exercise all parts of your body, it may also lead to little weight change.

Generally speaking, weight change is not the only goal of fitness, but more importantly, physical health and body symmetry. If you already have good fitness habits and diet plans and feel healthier and stronger, don't worry too much even if your weight has not changed significantly. Maintaining a healthy body and a healthy lifestyle will help you get better physical effects.