1. They don't diet
Or at least not in the traditional, all-or-nothing, deprivation sense of the word. "You need to get rid of that diet mentality and realize that what you are doing is making a permanent lifestyle change," says Anne Fletcher, M.S., R.D., author of the Thin for Life book series. She adds, "You do have to cut back on calories if you want to stay thin, but it's about reassessing what you eat and being more sensible in your choices, not about a quick-fix, crazy diet." Research has also shown that thin people tend to have a better quality diet than those who are overweight. They eat more fruits and vegetables and more fiber, and drink more water—all healthy things that provide more food volume for the number of calories.
2. They keep track of their weight
Thin people know how much they weigh, and they monitor that number by stepping on the scale frequently. It's not about a having an unhealthy fixation on that number on the scale, but it's a way to catch a 5-pound gain before it suddenly turns into a 20-pound gain. "Aim to keep your weight within a five-pound range, and if you see it go above that buffer zone, make sure you have an immediate plan of action for how to address it," suggests Fletcher.
3. They exercise regularly
"In my research, 9 out of 10 people who've lost weight and maintained it exercise regularly and make it a critical part of their lives," says Fletcher. Even if you've never been a fitness fanatic, it's not too late to get moving. Even taking a few 15-minute walks throughout the day will be a move in the right direction. Once you start to enjoy the mood-boosting and calorie-burning advantages of exercise, start looking for ways to keep your workouts interesting. Join a local gym and try a variety of classes and cardio machines, find friends to walk with, or experiment with at-home exercise DVDs.
4. They don't solve problems with food
Almost everyone is guilty of occasionally drowning their sorrows in a pint of Ben & Jerry's or taking out frustration on a batch of brownies, but thin people definitely don't make it a habit. "They tend not to eat purely for emotional reasons," says Fletcher. When you are upset (or bored, lonely, frustrated or angry), she suggests asking yourself: Is food really going to solve the problem, or will it just end up making you feel worse after you finish eating? Chances are, the food won't fix what's bothering you, so it's important to come up with a list of other small pleasures you can turn to instead of food. Some ideas include going for a walk, watching a movie, calling a friend, playing with your kids, or taking a bubble bath.
5. They stop eating when they're full
Most thin people are not members of the clean-plate club. Instead of mindlessly eating however much they are served, they pay attention to internal hunger cues and satiety. "Thin people are tuned into noticing when they are satisfied, and they stop eating even if there is food left," says Jill Fleming, M.S., R.D., author of Thin People Don't Clean Their Plates (Inspiration Presentations Press, 2005). "They often report that they don't like that feeling of being uncomfortably full, so they've learned how to stop before they reach it."
6. They don't surround themselves with temptation
Rather than stocking the cupboards with junk food, thin people's kitchens tend to be filled with healthy foods. That doesn't mean you can never have any indulgences in the house, just that you shouldn't have so many that you're likely to overeat them. For example, if you love to bake, give most of your sweets away to friends, or have your kids bring them to school or soccer practice, leaving just a few behind to enjoy yourself.
7. They allow themselves treats
It's the opposite of the deprivation mentality that many overweight (but dieting) people espouse: Thin people let themselves eat what they crave, sometimes even indulging in a treat every day. "The difference is that they do it consciously, choosing exactly what they really want to eat and then eating slowly and enjoying it," says Fleming. So if it's chocolate you want, don't try to eat around the craving with an array of foods that don't really satisfy you. Instead, allow yourself to have a small but really delicious chocolate bar and put the craving to rest.
8. They eat breakfast
According to the National Weight Control Registry, which tracks the habits and strategies of more than 5,000 people who have maintained a significant weight loss, nearly 80 percent of these successful losers eat breakfast every single day. And most of their naturally lean counterparts do the same, and make sure that eat within about an hour of waking up. "Breakfast is literally breaking the fast of the night," says Fleming. "Until you send food into your system, your metabolism doesn't really start to kick in."
9. They move, stand and fidget more
"Thin people are rarely sitting," says Fleming. Beyond their regular fitness routines, they simply move around more—and consequently burn more calories—throughout the day. And a study at the Mayo Clinic confirmed this: Researchers found that on average, a group of lean subjects sat for two hours a day less than the obese subjects, potentially burning up to 350 additional calories.
10. They don't skip meals