I once did a fast where I ate nothing but apples and drank a half of a lemon in a glass of water every hour waking hour for 2 weeks and lost a pound a day. When I tried it again without the lemon juice I gave up after a week because I didn't lose ANYTHING. I realized then that the lemon juice was crucial to the fat loss. I think it would be the same with vinegar because it's the acid which combines with your fat cells to give you energy, this is what the promoter of the fast said. Kind of confusing what the has to do with losing weight quick but all I know is that if you use a lot of lemon juice it will really speed up weight loss, and it's probably the same with vinegar.