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.
The human body is an adaptive organism and will fight any drastic changes trying to stay in balance.
You do realize that's pure speculation on your part. It's nice to be able to just say things like, "the brain is so powerful that if you imagine eating it will be like you did". But you actually need the science and data to back it up.
Furthermore, where is the line? Is 500 calories too much? What about a 50 calorie per day deficit? What about 1 calorie? Is it better to lose the calories per day, or in a single sitting? Does it matter the food composition? Does it matter if the deficit is paired with exercise? What if the deficit is purely exercise (no reduction in caloric intake)? Etc... You use the scientific method to try to understand this. Not just speculation from random Joe's on the corner, because frankly everyone and their mom has an opinion. And that's why everyone and their mom has a new diet they've just introduced.
Pubmed has a lot of abstracts pertaining to metabolic rate:
http://www.ncbi.nlm.nih.gov/pubmed/18198305
"Body weight is defended in non-obese participants during modest caloric restriction, evidenced by metabolic adaptation of RMR and reduced energy expenditure through physical activity."
There are plenty of other studies that support CR as a factor in lowered RMR. I read one (can't remember where) that used non-obese women. IIRC, the women on 300kcal deficits had no change in metabolic rate, while those on 500 did.
