If you are obese because you eat too much and your knees hurt, the solution is not an opioid. The whole discourse about pain being a condition that must be addressed is nefarious. Except in some pretty rare case (like terminal illness), pain is a symptom for which the healthcare organizations must find the root cause of and treat properly. Using expedient like opioids is a recipe for failure and a problem of that only the medical community can address. Serious introspection for those in charge of healthcare system in the US (and many other countries) is necessary.
Also, serious failures of the FDA for labeling opioids as not addictive and putting the breaks on fixing it for years.