The Biggest Loser gets criticized because there's a lot of relapse among former contestants. I actually think this is unfair--because the bar that needs to be passed to qualify as effective long-term is pretty low. We live in a world where a diet and exercise program can have most participants relapse and still be very effective compared to the average program. I'm not sure "can it be sustained long term" should be a criticism of a weight loss method, that's more along the lines of maintenance. Is the program on the ranch sustainable long term? No. But if the mainstream advice for maintenance, simply don't eat more than you burn was practical, it wouldn't need to be. They shouldn't pretend they've entirely cracked the maintenance problem for any dietary approach.