What I'm about to say, is from observation only.
Most (yes, most, not all) people that have a hard time eating after upping the intensity by quite a bit, means that they were not eating enough before.
In other words, your body is not adapting as your intensity went way higher then it should have.
My solution was to tone the exercise program down and concentrate on the diet. After things were in line, I upped the intensity gradually.
Biggest example was going from a three days a week program in under 75 minutes to switching to p/p/l program, 6 days a week, 90+ minutes. The dot cannot adapt that fast.