you are most likely not eating enough food and your body thinks you are starving. You need to find a meal plan that is more balanced, limit all processed foods and simple sugars, cut out all refined foods, no bread, or if you have some make it organic and WHOLE grain. You need to read the label for this not the title on the package. Stick to lean protein sources and complex carbs such as vegetables. Drink lots of water..

I have lost a lot of weight before and there are a few golden rules. You lunch should be exactly the same as your dinner. You need to combine lean proteins with a tinny ammount of carbs. Think two pieces of chicken one whole tomato, same for lunch and dinner. During the start of any diet the body looses arround 4lbs of water. Then for 3-4 weeks your body goes in shock, like cahardcore describes you go to starvation mode and the body trys to keep every cal you put on it. You have to keep pushing through that phase after those 4 weeks you enter cytosis and things become much easier. Limit your carbs dont eat sugar, chewing gums, sweets, soft drinks nothing is allowed if you are serious about your diet. Also make sure your last carbs of the day are at 18:00pm. Have lost arround 50kg in the past, hope this helps