They do, if taken properly, and preferably ones which've been prescribed by a doctor. I know someone who lost over 3 st. on some, but she was carefully monitored, because they can increase blood pressure and cause heart palpitations, etc. The tabs also have to be used alongside a careful diet. It's no good taking a pill and then having a pile of chips for lunch. The other thing, is that you have to exercise every day - walking & swimming particularly recommended, becausde the output of energy has to be more than the intake of it (through food). If you do this, you can expect to lose a steady 3-4 lbs a week, and by the time you've reached your goal, your body should've adjusted to taking in less calories. never buy the amphetamine-type tabs which're available on the internet. they can cause serious side effects, such as permanent heart trouble.