I can’t stress this enough. If I could afford a billboard to slap on every street in America it would say this…
STOP STARVING YOURSELF AND EAT DANG IT!!!
It’s not poetic but it gets the point across. Starving yourself to lose weight is not only unhealthy but stupid. OK maybe saying people are stupid is a little harsh but it’s the truth. I have talked to a ton of people who admit to eating less than 1000 calories a day and think that’s a healthy way to live. Do you know how crazy that sounds? 1000 calories is virtually nothing. One meal at Mcdonalds can have about 1200. A lot of these people who eat so little are actually quite thin but to be honest, they don’t look healthy. Typically they look to have little muscle mass and almost look to be emaciated. FACT: Being thin does not equal being healthy
It’s even worse for people who are over weight and choose to eat very little. Over weight people who have been eating 3000+ calories a day over a long time and by reducing your caloric intake to nearly nothing can send the body into shock. If you are feeding your body only 1000 calories a day eventually that will cause muscle loss and when you gain the weight back (and most people do) you actually end up fatter.
When you deprive yourself of food in order to lose weight, you lose muscle along with fat. This way when you return to the same lifestyle that made you overweight in the fist place, you gain back the weight and the total amount of body fat increases. The final result is that you become even fatter and end up having less muscle mass, which decreases your ability of burning calories. 
When you regularly eat too little food to provide your body with the necessary nutrients, it perceives itself to be in danger from starvation. Since your body is wonderfully designed to protect you, it will slow down your metabolism to conserve energy so it can keep vital organs such as the brain and the heart going for as long as possible in the face of the perceived threat. While it will burn fat for fuel, it will also start burning lean muscle mass for fuel, which will slow down your metabolism even further. People on starvation diets invariably find that they regain all the weight they’ve lost (and then some) very quickly as soon as they start eating again.