The body is only able to burn 70 grams (6 handfuls) of carbohydrates per day. Any excess of 70 grams causes your insulin levels to increase. High insulin causes a reduction in growth, sex and other hormone levels as well as increased fat storage.
There is no scientific evidence that low fat diets are healthy. People who do not eat enough good fat crave sweet things and tend to overeat because their body is not satisfied. Fat is best for satisfying your hunger.