The most effective fat burner isn't easy to say because not every burner is guaranteed to be effective. Our pick for the overall best fat burner for women is PhenQ because of its clean, science-backed ingredients and potent formula that hits weight loss from five angles. PhenQ is highly reputable, and popular, and may be effective for many, according to reviews. Lastly, besides a particular fat-burning brand, generally, fat-burners are most effective when added to a healthy eating and exercise regimen.