What are you feeding him? Does it look like he could be bloated or possibly impacted? Has he pooped lately? If he is impacted this could be why he is refusing food and appears fat. It also could be possible that if you got him as a baby or a juvenile he needed to eat everyday, and now that he is an adult he does not need to eat as often. I feed my adult FBTs 2-3 times per week, usually about 3-4 crickets per frog each time. Are you dusting the food? I dust my crickets with a multivitamin and vitamin D supplement once a week.