Why not? Ever heard of keto or paleo? This kind of result is common when you get serious and knock off the carbs. He obviously has the military discipline to pull it off, and he's WAY healthier for it. Before, he looked like he was about to pop.

I only dropped 15 my first month, but I wasn't an enormous moose like Pompeo was. I was only about 20-25 lbs overweight to start with.

One month is a lot of time to lose weight.

Or, certainly pre-diabetic at least.

It's almost physically impossible to accumulate the vast amount of subcutaneous adipose tissue he was lugging around, without first making yourself seriously insulin-resistant by overwhelming the pancreas daily with carbohydrate.