Keto definitely works well, but it's more of a lifestyle (like being vegetarian), not just a quick-fix diet. It doesn't change your body's underlying physiology, so it's of little surprise that when people stop eating Keto and resume carbs, the insulin-fat cycle resumes from where it left off and weight goes up.

Having said that, though, it's definitely not a fad diet where you're starving or eating only alfalfa sprouts. If you love eggs, cheeses, butter, meat, cream, cauliflower, broccoli, etc... then it's easy to stay satiated.

If you're an athlete, training while in ketosis has double benefit. You train your body to efficiently consume fat for energy, but it hasn't lost the ability to use carbs if they are present. So, during a marathon, for example, you can have a high-fat meal instead of carb-loading the night before, and also consume gatorade and gels during the run - a double whammy of energy sources.

The munchies during the first day are the worst (for me, at least). I wrote up a quickstart menu that I used as a jumpstart recently: https://steemit.com/lifestyle/@jfollas/keto-quickstart