Less fat means less loose fat, which is a good thing. Fat is always wobbly, muscles are strong, and it won't sway, indicating that you have lost fat and gained muscle, and some fat has become muscle. If so, weight gain is normal. Fat meat of the same quality is bigger than muscle, so it doesn't matter if there are more muscles. Besides, health indicators can't rely entirely on weight. Being as thin as bean sprouts is unhealthy.