"Chronic diseases like obesity and diabetes—which I have studied for over forty years—have increased in prevalence despite the fact that many new insights into their pathophysiology have been achieved and new treatments have become available. Changes in nutritional and other environmental exposures are certain to be important contributors, but the specific causes are vigorously debated, and new research insights are desperately needed to address these."

Yes and no. You might need specific causes if you want to solve this with a pill or at a 100% level. You could very well solve this for 90% of people with lifestyle changes. Just look at the Amish for obesity and type 2 diabetes. But being more active and eating less ultraprocessed stuff is too burdensome - we all want to eat our cake and have it too.