Why we gain more weight after going off diet?

The threshold of your body to produce insulin changes as your food intake levels changes

After you go off the diet and start to eat as before the dieting, the new threshold will release excess insulin at lower levels storing more of unused calories as fats. This causes people to gain more weight after they go off diet than the their original weight. Body slowly and continuously adjusts this threshold.

It is essential to continue exercising to prevent post dieting weight gain.