My husbnd's belly is huge!looks like he's 10m pregnant!but hes not obese.very active&a workaholic.why?

Visceral Obesity: You describe metabolic syndrome/pre-diabetes mellitus. Body stores fat (reserve fuel & padding) lots of places. The most active/higher blood flow fat deposits, termed visceral, are around arteries, veins & the deep internal, especially abdominal organs. The primary driver of storage is carb/sugar/etoh beyond quantities quickly burned. All excess rapidly converted into fats & exported to viscera.