Meh -- don't buy it, because the reasons and behaviours for weight gain are so personal...
1. Sometimes I skip breakfast -- I'll have water and go to Hot Yoga. Then I'll have lunch. Hasn't made me fat, cause it is just another way to manage my food intake.
2. 2 meals a day -- often I do this, no impact here...but I control my portions.
3. Nap after eating? I will if I'm tired...
4. BIG BEEF HERE -- I DARE you to do Hot Yoga after eating! You'll barf on your yoga mat. No food 4 hours before Hot Yoga is the rule of thumb, else you'll get sick. Love to see the author run 5km after breakfast!!!
5. I know my secret solitary eating behaviours get me into trouble. I eat with DH, and control my portions...
I think the way sumo wrestlers gain weight is that they eat huge portions, they continue to pack in the food well beyond the point of fullness, and they drink copious amounts of beer.
http://www.tinajuanfitness.info/articles/011403.htm
This probably has more to do with their weight gain than exercising on an empty stomach...