I took intro to nutrition for my nursing prerequisite requirement. No they are not true, especially the fruit part, they all have calories. One of the few really negative calorie food is celery, since it is high in fiber and requires more digestion but it's not significant amount. You can't just eat a pound of it and lose weight, it's very small. But the vegetables are so low in calories that you don't have to worry about it when you eat them. Only real way to lose weight is to eat healthy and exercise. Just run.