Reminds me of DNP: https://en.wikipedia.org/wiki/2,4-Dinitrophenol

The actual paper: https://www.nature.com/articles/s41586-025-08996-y

The most important part, especially if somebody is wondering if they might wither away, weaken from massive weight loss, and have a good chance of organ harm:

>We did not observe significant differences in muscle (quadricep) histology across the four groups (Extended Data Fig. 2f,g). In the liver, there was no significant fat accumulation or apparent pathology (Extended Data Fig. 2h,i). These findings may explain the lack of any effects on movement and the ease with which Cse−/− mice on a no-Cys diet can recover.

Unfortunately, an easy (maybe the easiest and most accessible) way to avoid cysteine and its precursor methionine is to have a low protein diet(Fruits, Non-starchy low-sulfur Vegetables, Fats and Sugars) but without protein you may lose a lot of muscle mass and have other issues as well.

30% weight loss in a week sounds more like dying than a dietary adjustment. I'm sure the side effects of this will be unpleasant.

Enjoy drinking your Soylent Zero Cysteine, everybody!!