are. >> reporter: similarly in the long run, she wasn't able to keep the weight off. >> i was able to keep it off for a little bit and i gained it back. and a little bit more. >> reporter: turns out, they're among the 85% of dieters who fail. recent studies say it's a matter of biology. >> your body starts to secrete hormones that make you feel hungrier. your brain responds more to food cues, telling you to eat those foods. >> reporter: but there is an elite group -- people who have beaten the odds. they're called super dieters. they've not only lost weight but kept it off for years. more than 10,000 are tracked in a database tracked by the national weight control registry. >> we have been able to study these individuals carefully and find out what strategies have been related to their success. >> reporter: the data suggests there are golden rules of these super dieters. rule number one, don't cheat. they never give themselves a break. not even on holidays or weekends. and rule number two, eat breakfast.