Most popular or most effective?

Effective!

The ones with research to back them up are green tea (effective and lots of health benefits), CLA (works, but subtle and long term), yerbe mate, caffeine (most popular diet pills are based on caffeine, but black coffee works as well).

If you are deficient in them, then adding fish oil, calcium, vitamin C and D and chromium to your diet can be helpful, but will do nothing if you are not deficient.

Most of the popular diet pills are based on caffeine with a sprinkle of vitamins and the latest wonder supplement. Right now, it's acai, but there'll be another one along soon.

Alli (over the counter form of Xenical) has research to show that it produces statistically significant weight loss. But that weight loss is 6lb A YEAR more than diet alone.

Pretty much anything else that is effective is either on prescription, or is illegal.

Until they invent the magic pill, I'd discourage using a pill. Your solution has to come from inside of you. And yes, it is basically move more, eat less, pay attention to your feelings that are encouraging you to eat. Think first. Learning these skills is a lifelong journey for most of us. Some move along the path more slowly than others.