Most Americans will follow some kind of diet at some point in their lives. Unfortunately, most diets have an extraordinarily low success rate. Around 80 percent of dieters regain all the weight they lost within a year, and 85 percent regain it within two years.[1,2] Within three years of finishing a diet, 95 percent of people regain all or more of the weight they've lost.[3] Of those who regain weight, at least one in three puts on more pounds than they originally lost.[4]

When they try to lose weight and fail, many people think it's because they don't have enough willpower, so they grow discouraged and resume their normal eating pattern. But failure is often due to diets that ask people to make radical changes in how they eat.

To produce long-term results, your diet must be sustainable. And part of eating sustainably is avoiding these five dieting pitfalls.

1. You Resort to the Latest Fad Diet

Blood-type diet? Tried that. Gluten-free diet? Yep. Paleo? Check. HCG diet? Been there. How about the Lunar diet? (Yes, it's a real thing.) The list goes on. We all know people who've tried every fad diet known to man, only to end up back where they started—if not heavier.

Why is that? Generally, diets that are heavy on promises but light on science tend to produce only short-term weight loss at best. Instead of focusing on reasonable, sustainable dieting, people often focus on an immediate objective: They want to lose weight for the holidays, for a wedding, for the beach.

It is possible to reach these short-term goals. But as bikini pro and amateur powerlifter Sohee Lee, CSCS, says, "If you can't see doing the diet you're currently on for 3, 6, 12, or 18 months into the future, rethink your plan, because it's going to fail."

2. You Eat More Calories Than You Think You Do

Research into dieting shows that most people underestimate the number of calories they take in—and obese people tend to underestimate more than lean people do.[5,6] Trace calories are one of the biggest culprits. For example, a piece of gum contains 2 grams of carbohydrates. A packet of sweetener containing maltodextrin or dextrose has around 0.8 grams of carbohydrates. And while vegetables are vital to a healthy diet, you should track those carbs as well.

It all adds up. If you chew three pieces of gum, use five packets of sweetener, and eat four servings of vegetables each day, that adds up to more than 30 grams of untracked carbohydrates each day. Couple this with a tendency to underestimate calories in general, and you can see how your calorie intake may not be aligned with the results you expect.

If you're not meeting your weight-loss goals, it might be that these hidden sources of calories are slipping by uncounted.

3. You Try to Diet Too Rapidly

If you try to drop 3 pounds per week, you'll probably feel miserable. As you probably know, feeling starved increases the likelihood that you'll break down and overeat or binge eat.

A very-low-calorie diet can also send your body into survival mode. When this happens, your body reduces its metabolic rate and stores those scarce calories as extra body fat—the exact opposite of the result you want.[3,4] Again, focus on a rate of fat loss you can sustain, one that doesn't require extreme levels of calorie restriction.

4. You Don't Give Yourself a Break—or a Reward

It takes time to lose weight when you want it to stay off. If you're 100 pounds overweight, don't expect to be shredded in six months, or even a year. You put that weight on over a long period of time, and it's going to take time to permanently lose it.

Divide up that time by giving yourself milestones to hit along the way. Celebrate every time you lose another 5 pounds or every month you stick to your diet. Maybe give yourself a planned "diet break"—a week or two off when you return to what you would consider a maintenance level of caloric intake.

These short breaks give you a chance to cleanse your mental palate, reward yourself (in moderation or in some other way that doesn't involve food), and possibly increase your metabolic rate a bit. They also give you a brief vacation from your diet and something to look forward to.

5. You Don't Give Yourself Enough Flexibility

Most diets are based on rigidity: Don't eat this, don't eat that, and make sure you limit yourself to a short list of food choices. Some diets may even force you to cut out entire food groups. While these diets can produce short-term weight loss, they are unlikely to produce lasting results.

If you're about to start a diet, make sure it gives you the option to eat almost anything you like, as long as you "calorically budget" for it. If you want to eat that 400-calorie slice of pie, make sure you deduct those calories from your daily caloric goal. And before you dig in to that slice, make sure you have enough room in your calorie count to get the protein, fiber, fat, and carbs you need.

Join the 5 Percent!

Remember that research result: Within three years of finishing a diet, 95 percent of people regain all or more of the weight they've lost. To avoid that fate and join the 5 percent who succeed, focus on long-term success and sustainability.

Reaching long-term weight-loss goals requires patience. But it'll be worth it when you realize that the changes you've made will help you manage your weight—not just for the next 3-6 months, but for the rest of your life.

References

1. Kraschnewski, J. L., Boan, J., Esposito, J., Sherwood, N. E., Lehman, E. B., Kephart, D. K., & Sciamanna, C. N. (2010). Long-term weight loss maintenance in the United States. International Journal of Obesity, 34(11), 1644-1654.
2. Ayyad, C., & Andersen, T. (2000). Long‐term efficacy of dietary treatment of obesity: a systematic review of studies published between 1931 and 1999. Obesity Reviews, 1(2), 113-119.
3. Langeveld, M., & De Vries, J. H. (2012). [The mediocre results of dieting]. Nederlands tijdschrift voor geneeskunde, 157(29), A6017-A6017.
4. Dulloo, A. G., Jacquet, J., & Montani, J. P. (2012). How dieting makes some fatter: from a perspective of human body composition autoregulation. Proceedings of the Nutrition Society, 71(03), 379-389.
5. Taksler, G. B., & Elbel, B. (2014). Calorie labeling and consumer estimation of calories purchased. International Journal of Behavioral Nutrition and Physical Activity, 11(1), 1.
6. Lichtman, S. W., Pisarska, K., Berman, E. R., Pestone, M., Dowling, H., Offenbacher, E., ... & Heymsfield, S. B. (1992). Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. New England Journal of Medicine, 327(27), 1893-1898.