My son was on sort of a modified atkins - ate little but burgers (no bun) and pork rinds - and lost 100 lbs. Has kept it off 3 years (well, gained some back, but he got a foot taller). Maybe not a real healthy diet, but he’s better off now without the extra weight.
Oh, I forgot to mention when I posted my success story: My oldest daughter (she’s 16) has taken off about 25 pounds on the same plan. She went from a size 16 to a size 12. Hubby has been following it, too. He’s only lost about 15 pounds, but he’s lost about 4 inches around his waist! All his pants are falling off of him! And he says that, unlike when we were going low-fat, he doesn’t crave chips and such!