BioLayne did a good video about metabolic damage from such low-calorie dieting. his angle was more focused on fitness competitors, but his message was/is the same: if you want to be fabulous & stay thin without going out of your mind, you have to heal your metabolism first & only then move on to losing weight. He does this w/his clients by, yes, increasing their calorie intake over the long term (I repeat: long term) and only then starts to whittle them back down to competition levels of body fat. In one case, his client stays only 4 pounds above her stage weight in the off season & eats a boatload of carbs (400-500g per day, I recall) & is happy. My takeaway is that if your metabolism is healthy – or healthier, at least – you no longer need to plummet your caloric intake to concentration camp levels & play diet-roulette with your poor beleaguered metabolism for the weight to come off. But that takes time and patience is that very annoying grown-up attribute which is pretty much MIA these days.