"last year i started taking phentermine 37.5 mg and lost about 15 pounds, but when i stopped i gained it all back. so i went back on it december 1 and started weight watchers at the same time. eight weeks later i have lost 21 pounds. and my cholesterol has dropped 30 points already from 189 to 159. the key this time around is the ww. you&#039;re wasting your money on the phen if you don&#039;t follow some sort of diet program and learn to change your eating habits for life. my downfall last year was thinking i could eat anything i wanted and not gain weight, and that&#039;s why you gain when you stop taking the pills. i am 59 years old and can&#039;t do that anymore."