As your insulin sensitivity decreases, you will become more fat and this leads to leptin resistance. Leptin is a hormone produced in fat cells and controls appetite. As the fat cells increase, the amount of leptin produced increases and a signal is sent to the brain that "there is enough fat storage, decrease appetite". As the fat cells increase, more leptin is produced and enters the bloodstream. Eventually, leptin resistance occurs when the leptin ratio remains high for a long time. That is, leptin stops working. so the brain's “I'm full” command is useless and you lose your appetite control. This causes a bad vicious circle. The more you eat, the more fat you get, the more fat you get, the more leptin is produced and the more leptin is produced, the more leptin resistance occurs. You lose more appetite control and eat more.
When insulin is high, our body uses more carbohydrates and when low, fat is used as energy. high insulin = use carbohydrates, low insulin = use fats