The whole weight loss approach described in the article seems flawed to begin with. The human body is an adaptive organism and will fight any drastic changes trying to stay in balance. 500 calories a day will certainly cause the body to begin changing hormone levels. Then you come out of it after a while and start eating correctly you still have severely imbalances hormones (relative to normal levels). So now you're eating healthy but have completely screwed up the way your body handles food, essentially storing more calories than before. If you slowly shift into better habits and allow your body time to keep up you'll end up with a calorie burning machine. The main problem is people get so motivated to change they dive in head first (such as. 500 calorie per day diet), throw everything out of whack, try to maintain their losses which start coming back and end up worse than where they started.