What fruits are the most effective in weight loss?

Depends: Even an elephant is a vegetarian. In other words any fruit in big amounts will cause you to gain weight. So as far as "effective" and fat burning, there are none if you eat too much. Now in small moderate amounts, avocado, citrus fruits, coconut, and grapefruits are always touted as having the best fat burning properties by the registered dietitians i work with.