How long have you taken it? I tend to plateau and I generally take a few weeks off of it to level out. I didn't know about this site and hadn't read the report about how to keep from building a tolerance for it so I'm anxious to try again and see if the amino acids and/or fewer cups of coffee each day makes a difference.
I know that vitamins help and water makes a big difference. Whether you're on phentermine or not, dehydration can really slow you down so make sure you're getting enough water. I'm hypoglycemic so during PMS I tend to eat things that are not good for me nor my energy level ... I have to have a protein with every meal and stick to good carbs if I want to maintain energy and keep from being really irritable. There are lots of factors that can play a role, however, hope this triggers some ideas that might help  .
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