The point is that certain diets are more likely to prevent non-overweight individuals from remaining non-overweight. Example study where participants ate two different diets, one highly processed and one less processed, that were matched for macronutrient and calorie content: https://www.cell.com/cell-metabolism/pdf/S1550-4131(19)30248...
No, I don't agree. We have evidence to suggest that a large number of normal weight people have poor metabolic health, likely due to diet: https://pubmed.ncbi.nlm.nih.gov/30484738/
Not sure about the drugs, particularly if treatment has to continue indefinitely in order for people to keep the weight off. Someone else on here linked to a blog post about how those drugs increase the number of fat cells in the body but prevent fat cell hypertrophy, suggesting that rebound weight gain after the drugs are stopped could potentially leave patients worse off than they started. Most adults do not gain new fat cells when they gain weight, their existing fat cells merely get bigger. Leaving people with more fat cells than they had to begin with might make it even harder for them to maintain a lower weight without the drugs, given that fat cells are metabolically active. Who knows how many people may end up stopping them due to side effects or complications like the thyroid tumors these drugs are known to cause in mice. We know very little about the potential unintended consequences of these drugs.
