"i started phentermine on 5-26-2015. first day taking it, i got shaky, the chills, and my heart raced, but it will be 2 weeks tomorrow and those symptoms are no longer there. unfortunately i don&#039;t get much energy as others described, but my appetite has decreased a lot and i get fuller easily. i&#039;ve lost 15lbs so far, but i eat about 1300 to 1600 calories a day, and walk every day."