I know my female is underweight. My male is four months old, and after she pooped they are the same weight and he has more girth. She is 6-8 inches longer than he is and he has more girth. I tried to bump her up to 20% tonight but she just finished shedding and only ate one weaned rat at least she got 10% of her body weight. I may even consider 30% starting next week and take it back to once a week instead of five days so I can pack some weight on her, she should be at least 600 grams right now.