It's not that I'm not thin, but I can't see it. Your body fat has definitely decreased and your muscles have increased, but the increased muscles are similar to the lost fat, so your weight has not increased. It doesn't matter. Just pay attention to nutrition. Don't count calories during muscle gain, eat as much as you can, whether it's fat, carbohydrates or protein. No, eat hard. I believe you will gain weight again in a month.