There has been some talk on here about how you shouldn't go below X calories on a diet, and I was researching trying to figure out what X is. Then I stumbled on the PSMF diet. Protein sparing modified fast. You eat 1.5g protein per kg of lean body mass, some non-starchy vegetables, vitamins, fish oils, and nothing else. This adds up to 800 calories at most. This diet was created for and proven on the bed-ridden morbidly obese. Active people may need to up the protein number a bit. This diet may impossible to follow, but it will burn fat like nothing else. Who wants to try?