Your body needs calories to function properly. On average, a woman should have a minimum of 1600 calories a day, while men need a minimum of 1800.
Now, if you live a pretty inactive lifestyle, spend your days working at a desk, spending your evenings on the couch, then most likely you are not in the best shape of your life, even if you’re dieting really hard.
You need to be active. You should spend 2 or 3 days minimum each week weight training. This will help build muscle mass. This is when you actually need to increase your caloric intake. The idea is to build some muscle, and burn off fat in the process. You cannot do this efficiently if you are starving yourself of much needed calories.
Eat healthy foods. Doing this will increase the amount of food you can eat, because healthy food is less calorie dense.
Add cardio a few times a week. This increases the rate you burn off any excess calories, and allows you to eat more just in case you’re lacking in energy.
Cutting calories too low will cause your body to think it’s starving. At that point, it is incredibly hard to keep fat off, because your body will see every bit of excess calories as fuel that it needs to store, which is where fat comes from.
So basically, you need to eat enough every day to avoid starvation mode, but eat healthy foods. You need to exercise, but not just cardio. Weight training is very important for fat loss. Build some muscle, eat healthy, and you will lose that fat.