Have you looked at the food labels on the side of a lot of "healthy" snack packages? They say "low fat" or "no fat" on the labels, but on the side you see the real truth. They often have lots of extra sugar to replace the fat. The calories are about the same, or even higher in some cases. Don't forget, even though it's lower in calories per gram than fat, sugar in excess turns to fat on your body.
Your body knows the truth. It cannot be fooled! You probably know what happens to excess sugar (of any kind, processed or natural) – it turns to fat, or added storage of excess energy. Just because the label says "no fat," this does not mean that the product will not turn to fat, if you consume too much of it.
Be careful. I think it's better to just eat regular food, even with fat, but just have one serving.