The Keto Diet a.k.a. Atkins Diet, a.k.a. phase 1 and 2 of the Dukan Diet, etc. Essentially, a low carb (under 50 – 20 grams a day depending on your activity level) ketogenic diet has been around for decades now and was widely used to promote weight loss.
https://www.jillianmichaels.com/blog/health-and-fitness/truth-about-keto