https://astralcodexten.substack.com/p/shilling-for-big-mitochondria

In the 1930s, a shady outfit called Isabella Laboratories made a popular over-the-counter diet pill called Formula 281 (slogan: "281 for the too weighty one"). If you're familiar with any of: the 1930s, shady pharma, or diet pills, your next question will be "did it contain amphetamines?". Actually, no! It contained 2,4-dinitrophenol, a mitochondrial uncoupling agent.

DNP is that rarest of birds: a weight-loss pill which really works, no diet or exercise required. About 100,000 people used it in the mid-1930s. On average, they lost about 2 to 5 pounds per week, for however many weeks they wanted to keep losing it. The formula stayed popular until it was banned by the FDA in 1938, about one second after Congress passed the law saying the FDA could ban things.

What was the catch? Well, several catches, really. Many users went blind. Others got rashes, liver problems, kidney problems, or peripheral neuropathy. A few died horribly, apparently burning to death from the inside. Occasionally the DNP would just explode - the "di-nitro" of DNP is pretty similar to the "tri-nitro" of TNT, and it turns out that's not a coincidence. As far as I know, DNP is the only substance to be banned by both the FDA and the Department of Homeland Security for unrelated reasons.