Which is the quickest way for a teen to lose weight?

Weight loss: No easy answer. There are a very large number of diets and diet pills sold but none are reliable nor life long. Weight lose will vary even with the same person. In general, eat normal meals, even have small snacks, but cut out any binging and no extra helpings. Exercise daily for an hour a day but try not to build up muscle mass. If you teen is willing i would suggest calorie counting.