Not exercising or exercising too much
You will undoubtedly lose some muscle mass as well as fat during weight loss, however, the amount depends on several factors. If you don't exercise at all when calorie-restricting, you're more likely to lose muscle mass and have a lower metabolic rate. Exercising, on the other hand, may be beneficial in minimizing the amount of lean mass you lose, increasing fat loss and preventing your metabolism from slowing down.
The more lean muscle mass you have, the easier it will be to reduce weight and keep it off. Overexercising, on the other hand, might be unhealthy. Excessive exercise, according to studies, is unsustainable in the long run for most people and can contribute to stress. Furthermore, it may have a negative impact on endocrine hormones, which help regulate body functions. Exercising excessively to force your body to burn more calories is neither productive nor healthful. Lifting weights and doing cardio several times per week, on the other hand, can be a long-term strategy for maintaining metabolic rate while losing weight.