I wrote about a friend a few weeks ago who wants to get his weight down to a certain number, despite already losing over 100 pounds. Recently, he told me he wants to cut his calories in half. To me, this is dangerous, not just because of the potential for developing an eating disorder, but because cutting calories will not result in sustainable weight loss.
Too many people think that by not having enough calories, they will lose weight. Well, all that will happen is that the metabolism will slow down to a crawl. Do you want to feel tired and have no energy? That's what happens with calorie restriction.