Methamphetamine (desoxyephedrine) was first approved in 1943 by the FDA for treating narcolepsy, mild depression, postencephalitic Parkinson syndrome, chronic alcoholism, cerebral arteriosclerosis, and hay fever. Later, in 1947, methamphetamine was also approved as the first drug for treating obesity.
It’s literally FDA approved for weight loss.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5473499/