To many, this is an unexpected question as cardio (the sweaty type) has always been associated with weight loss. You may also recall the simple rule: to lose weight one must eat less and move more.
The reason cardio is controversial for weight loss is because of the phenomenon called over compensation. Some people over eat after they engage in cardio either because they overestimate the calories they burned through exercise, or they fall victim to an increase in hunger.
The solution is thus two-fold.