Weight loss or gain is 80% calorie intake and 20% calories burned by exercise. Exercise to building muscle mass causes more calories to be burned due to muscle burning more calories than fat. But, it takes a lot of exercise to burn off 500 calories of excessive eating.

I dropped 30 pounds and have kept it off by changing my eating habits. No more soda ( couple servings a week). I still have an occasional treat but in moderation. 2 cookies is enough to make my need for a sweet feel satisfied. I am as sedentary as a couch pillow but my weight stays off.

The struggle is the change in lifestyle to avoid stimulation means spending more time bored and near food sources.

The fatigue is more often from poor sleep than anything else. The brain does tire of cognitive effort more easily and will fatigue from stimulation. A small disruption in sleep can make these other factors much worse.