I am having the same experience with exhaustion and headaches....I was already on a low-fat diet and have not had to withdraw anything...I do not drink caffiene...so that's not the problem either.  The only thing new is the alli pill.  Any ideas to why?

 Hello. alli is very minimally absorbed - only about 5% of the dose gets into your bloodstream so it is usually unlikely that it would cause systemic side effects. It is possible, however, and if alli is the only factor that you can contribute these effects to, you have 2 choices. Either wait it out - side effects usally sibside within 1-2 weeks of starting the product - or stop the alli and see if the effects go away. If you chose to wait it out, be sure to drink plenty of water throughout the day to keep hydrated (dehydration can cause headaches and tiredness), and get some exercise which is naturally energizing.

Hope this helps. Best of health!