Picking a Weight Loss Supplement

How do you pick a weight loss supplement?  Do you just pick up something off the store shelf and hope for the best?  Do you talk to your doctor?  Do you research online with the company?  Do you look for scams?  For instance, if I was considering Apidexin, I'd want to look up reviews from real people as was as google apidexin scam and make sure it was a legitimate supplement.

I would also talk to my doctor because I take medication for asthma and thyroid disease. It would be very important to me to make sure there wouldn't be any dangerous interactions, especially because of my thyroid medication.