The first step is to eat lots of beans. This will produce intestinal gas.
The second step is to plug your butt with a cork. By plugging your butt, the gas cannot escape. This will make you feel (and be) full. Thus, you will no longer feel hungry and cut down on eating.
DISCLAIMER: This has caused lab rats to explode. Intestinal explosions have been associated with dismemberment and death in some medical simulation models. Thus, we recommend wearing a helmet and not coming too close to children and pets.
Good luck on your new diet!