Sugar and (refined) carbohydrates make you hungry:
Refined carbohydrates are converted into sugar very quickly.
Sugar gets into your bloodstream as Blood Glucose.
Blood Glucose spikes Insulin.
Insulin takes glucose out of the bloodstream (and stores it as fat). Insulin prevents you from burning fat.
This rapidly decreases Blood Glucose, stimulating the release of Ghrelin, the hunger hormone.
The Glycemic index of a food is the speed at which it is converted into glucose (Glucose has a Glycemic index of 100).
Eating fat satiates you so you do not feel you need to snack between meals... so the Low-Carbohydrate, High-Fat (LCHF) lets you lose weight without feeling hungry or counting calories. This is why (I)F works so much better when it is combined with a Low (or moderate) Carbohydrate, High-Fat diet.
This video also explains the benefits of drinking Green Tea: