When you lose weight, you may lose weight but your weight has not changed. This is because after a certain period of exercise, the speed of muscle synthesis in our body has slowly "caught up" with the speed of fat consumption. At this time, the muscles will gradually increase and the fat content will gradually decrease.
Weight loss mainly depends on body fat rate, and we can't blindly pursue weight loss. Some people are light in weight because of osteoporosis.
People with high bone density will naturally be heavier.