1. You hoard calories
Yes, cutting total calories leads to weight loss. But bank most of those calories for the end of the day and your hunger hormones will go haywire, making you eat more. Middle-aged men and women who ate their daily number of calories in one supersize supper produced more ghrelin, a hormone that causes hunger, than when they ate the same number of calories in three square meals, found researchers at the National Institute on Aging.
Smarter move: Front-load your calories. Overeating at night keeps you from being hungry in the morning, setting off a vicious cycle in which you're never interested in breakfast but always starving by dinner. The key is to rebalance your day so you don't set yourself up for an evening binge. To get your appetite back in the morning, cut your evening meal in half. Then eat a breakfast of about 450 calories, such as a scrambled egg with low-fat cheese on a whole wheat English muffin with an 8-ounce glass of juice—an amount that should keep you satisfied until lunch, says George L. Blackburn, MD, PhD, associate director of the division of nutrition at Harvard Medical School and author of Break Through Your Set Point. Once your appetite adjusts, don't go more than five hours without another meal of roughly the same size.
2. You eat erratically
Trouble is, grazing may contribute to weight gain, according to a study in the American Journal of Clinical Nutrition. When researchers asked women to eat at regular, fixed times or to break their usual amount of food into unscheduled meals throughout the day, they made a startling discovery: The women actually burned more calories in the three hours after eating the regular meals than they did after the unplanned meals. They produced less insulin, too, potentially lowering their odds of insulin resistance, which is linked to weight gain and obesity. What's more, grazing instead of planning ahead can set you up to eat mindlessly, says Zied. In the end, we rarely realize how many calories all those little nibbles and noshes really add up to.
Smarter move: Figure out how many times a day you need to eat—everybody is different—and then stick to a schedule. "It's not great to feel starved, but it is okay to feel slightly hungry," says Dr. Zied. You can home in on your body's internal cues with a food diary. It's so effective that earlier this year, researchers at Kaiser Permanente Center for Health Research found that dieters who kept a food journal lost twice as much weight as those who didn't record what they ate.
3. You don't count calories
People consistently underestimate the calories in nutritious items such as yogurt, fish, and baked chicken, found researchers at Bowling Green State University who quizzed students on calorie counts. "Just because a food is healthy doesn't mean you can eat big portions," says D. Milton Stokes, MPH, RD, owner of One Source Nutrition in Stamford, CT. "A handful of nuts can be 200 calories or more. And if you add that without cutting back elsewhere, it could be the reason you're not losing weight."
Smarter move: Count all calories. Once you learn that 1/2 cup of cereal can have as much as 200 calories or that there are about 220 calories in that "single-serving" bottle of OJ, you'll be more prudent about how much you use.
4. You crash diet
Slashing significant calories might sound like the fast track to weight loss, but it's likely to backfire. In fact, nutrition experts recommend you don't dip below 1,200 to 1,500 calories a day. "If you crash diet for more than two weeks or so, your metabolism will temporarily slow down," says Blackburn. "So the same exact dieting effort results in less and less weight loss." The reason: Your body is conserving energy to keep you from losing weight too quickly. And that's not all. When you drastically cut calories, you lose muscle along with fat—especially if you haven't been exercising. Because muscle is your body's calorie-burning furnace, this can slow down your metabolism, even long after your crash diet is done. Smarter move: Aim to shed about a pound a week—the slow, steady weight loss ensures you lose fat, not muscle. "If you want to lose 10 pounds, get started 10 weeks before your goal, not 4," says Blackburn. "You'll have a better chance of actually taking off the weight permanently." To drop a pound a week, shave 250 calories from your diet and burn an extra 250 calories through exercise each day.
5. You set short-term goals
The National Weight Control Registry estimates that only 20% of dieters successfully keep off lost weight for more than a year. That's because after we reach our goal, we let old eating habits creep back in. But people who win at weight loss consistently eat the same way even after they've slimmed down. In fact, the NWCR found that dieters who maintain their healthy eating habits every single day are 1½ times more likely to maintain their weight loss in the long run than those who relax their diets on the weekends.
Smarter move: Think of healthy eating as a work in progress, not as a "diet" with a beginning and an end. The key: making small changes you can maintain so they become long-term habits. Start by creating a list of problem areas in your diet, then tackle them one at a time. For example, if you snack on a heaping handful of Oreos every night before bed, set a goal of having two instead of six, and cut back by one a day. Once you've made that a habit, pat yourself on the back and move on to your next goal.
6. You load up on "low-fat"
Research suggests that when a food is described as a diet food, we're subconsciously primed to eat more—even if it's actually as caloric as regular food. When Cornell University researchers offered the same M&M's candies labeled either regular or low-fat to visitors at a university open house, visitors ate 28% more of the "low-fat" snacks. While less fat does not mean fewer calories, people make the assumption that it does, setting them up to overeat, say scientists.
Smarter move: First, check food labels: So-called diet foods frequently don't save you calories. Take low-fat chocolate chip cookies—because they've been infused with extra carbs to add flavor, you save only three calories per cookie. Once you have that reality check, follow the golden rule for any food: Keep close tabs on portions. Limit yourself to two small cookies, for example, or trade in a bowl of frozen yogurt for a kid's-size scoop; measure out condiments such as low-fat sour cream or low-fat ranch dressing. And remember—if you prefer the flavor of full-fat foods, you'll still lose weight if you watch your portion sizes.
