Welcome to the newest MedHelp doctor forum! It's been a slow start; we're glad you found us.
As you obviously know, but other readers may not, orlistat (trade name Xenecal) inhibitis fat absorption from the intestine and is prescribed as a weight loss aid. There are no reported interactions between orlistat and either Truvada or Kaletra. That doesn't prove adverse interactions might not occur, but it certainly is unlikely. To the extent you want to avoid any problem, here's something to consider: your HIV drugs are approved to be taken either on an empty stomach or with food, but to be effective, orlistat must be taken with a meal containing fat. So if you take your Kaletra and Truvada at least an hour before or 2 hours after eating, and take orlistat with meals, it should reduce any slim chance of some sort of interference.
As always, MedHelp recommends questioners under regular medical care cross check our advice with their health care providers. This question probably isn't worth an extra visit to your HIV/AIDS provider, or even a phone call -- but you should ask about it during your next routine visit. In the event you get different advice, please return with a follow-up comment to let me know.
Best wishes-- HHH, MD