"i&#039;ve been on phentermine for 17 days now and i started at 181 lbs. i weighed in a 168lbs this morning. i&#039;m still hungry while taking it, but i don&#039;t eat huge plate fulls like i used too. sometimes i eat very little, like 5 bites of food all day.  i do not have increased energy, actually i was quite tired the first week. the second week, insomnia. i actually stayed awake for over 24 hours one day last week. i&#039;m 29 and haven&#039;t done that since i was a teen. no headaches or nausea. extreme dry mouth and diarrhea every other day, also whenever i stand up i have to do it slowly, i get dizzy every time and almost fall over. i work out 3 times a week to kickboxing but that&#039;s about it, besides chasing my kids around."