Male
Female
I can't tell from that pic of yours as you can't really see the area where the sex organs are stored. Try taking a pic with tail lifted like above photo and I can tell you if its M or F.
I wouldn't worry too much about him slowing down on the feeding until he looks like he's losing weight. As they get older they tend to slow down on the feeding form time to time. Just make sure he's getting plenty of uva/uvb exposure as
sometimes lack of appetite is an early sign of Metabolic Bone Disease. But in your case, with that fat happy lizard, I would say it's just that he's getting older so he's slowing down. How old is he anyway?