So fruit sugar, will it make you fat? And the quick answer is, yes and no. It can. Certainly it's possible to get a lot of calories through fruit, and it boils down mostly to that. And sugars can turn to fat in the body.
That being said, I know fruitarians who eat a diet 90 percent fruit, no fat at all. An incredibly low fat content. There's one triathlete who is a fruitarian and he wins many, many triathlons. He's won back to back, one week to the next, triathlons, which is incredibly hard. And just eating almost primarily, only fruit. But also he is exercising a lot.
So it's kind of like with any kind of food. If you eat too much, yes you can gain weight, and if you're not doing enough exercise. But for the most part, it's no different than any other food. You're not going to necessarily gain weight just because you're having fruit.
Also something that can effect that also, is food combining. If you combine fruit when you're eating proteins and so on, it's not the best combination. And you're body won't digest it as well, and potentially you could have problems with gaining weight by improper mixing of fruits and other items that might not be the best for your digestion.
So one of the best ways to eat fruit and not gain weight is, just have fruit on it's own. Let your body digest it and you'll be fine.