> not only regained significant amounts of the weight they had lost on the drug, but they also saw their cardiovascular and metabolic improvements slip away. Their blood pressure went back up, as did their cholesterol, hemoglobin A1c (used to assess glucose control levels), and fasting insulin.

This does sound like "reversion to the mean", but saying it's "regaining weight" may be missing the bigger picture. More like "losing all previously gained health benefits."

It's less clear how "unsafe" those regressions in health markers are.