This was one of the 'truisms' I found on sites I was visiting during my journey. This research seems to back it up for mice at least. The claim is being overweight makes you lethargic. Overweight people are not 'lazy'.
I could exercise but nothing like now. I also credit going 'Primal' not only with my weight loss but also appetite loss. And 'allowing' me to run. I was very active growing up. But never a runner. Even got diagonised with exercise induced asthma. I had lousy food: school lunches, fast food and TV dinners at home.
In any case very active now. But this is an unfortunate 1-2 punch. Good news is anyone can turn it around.