At the end of World War II, researchers starved 36 young male volunteers for 24 weeks, giving them a low-fat diet limited to just 1,600 calories a day, which was 600 to 1,500 calories fewer than their body needed (depending on their level of daily activity) to maintain a healthy weight.
Though the men lost about a pound a week for the first 12 weeks, they lost only one-fourth a pound a week for the last 12 weeks. Worse things happened as well: Many became obsessed with the thought of food, began to lose their hair, and noticed that their wounds seemed to heal more slowly.
When the men were finally allowed to eat freely, many went on extreme binges, consuming as much as 10,000 calories a day — five times as many calories as they needed. Twenty weeks after freedom the men had gained an average of 50% more body fat than when they began the study.
You cannot go hungry forever, and your body doesn't want you to, so be smart about losing weight. First, know how many calories your body needs with online calculators like this one from the Mayo Clinic, and then reduce your caloric intake moderately.