I can eat "millions" of calories as long as little wheat/milk
I eat tons all day long, and ever since one bad experience in college when I ate way too much wheat/milk/sugar (and gained lots of weight) ever since I've kept these three foods (which are the worst for type o's) to a minimum. Result: I eat what my friends say are "millions of calories", and only weigh 125. I'm 5'7" female, in late 30's. This has been the case since I wised up in college, at about age 26.
Fats literally don't seem to cause an ounce of weight gain in this type O! despite their high number of calories. And red meat - same thing.
I do eat lots of other grains because I don't have the willpower not to (other than corn, which I don't really like). so I do have other health problems, and I'm not convinced that Dadamo's program works well for those other health problems, as I've tried his full-on diet, and not had results in those health areas. But as for maintaining proper weight, just cutting the 3 or 4 worst offending foods for your blood type can work wonders - and allow big meals.