There's definitely a difference betwee n being "thin" and being CR. From what I can see of Whoa's diet he is eating pretty low carb, avoiding grains and dairy. Those are 3 things just "thin" people don't necessarily do. Add on top of that whatever metabolic changes happen to CR people and you've probably got a recipe for a much healthier, longer, less aged life.

My Mom is thin too at age 86, but she's thin because of a side-effect of COPD. She's also going downhill very fast right now. Failing vision, glaucoma, corneal damage, maybe a bit of senility, osteoperosis (probably due to gluten intolerance), and blood sugar issues. She doesn't want to change her diet even though she now knows, thanks to a DNA test I had, that she probably shouldn't eat wheat.