I have only been taking Phentermine for just over a week. My doctor recommended starting with half the pill to see if that dosage would work. I lost 2 lbs. the first week! I just started on protein shakes today as a meal replacement and am eating one healthy meal a day. However, I'm wondering if that is the best diet. I want the weight to come off and STAY off, so I want to do the right thing. Also, I had LOTS of energy the first week, but am now finding myself wiped out half-way through the day. Is that normal? I'm wondering if I should take the entire pill instead of just half...Any advice would be appreciated!