Could You Lose Weight On A Fruit Diet? Could you lose weight on a fruit diet ? The answer is yes you can lose weight on a fruit diet. I would not suggest going on a fruit diet as a permanent choice. Rather you can use fruit diets as a way of fasting to clean out your system. There are different fasting periods you can use. The 1 day fruit diet is the easiest and of course does the least to help your body out. Then you could do a 5 day fruit diet which will help you out immensely. The most powerful fruit diet would be a 10 day fruit diet, which I would not recommend unless you have already done the other two fasting periods.