The Alkaline Diet. The Baby Food Diet. The Blood Type Diet. The Paleo Diet. The HCG Diet. The list goes on and on...

For people who are overweight or obese, and have tried to lose weight without success, fad diets offer hope. “Perhaps this one will work,” we think. Yet most experts note that the reason there are so many fad diets is because they don’t work for long-term weight loss, leading people to continue the cycle of try and try again.

“Fad diets come and go. Anything to promise a quick fix appeals to the public,” says Dotti Durbin, a Washington University diabetes educator and registered dietitian. “Some popular diets, such as South Beach, have some good attributes and have taught America about the importance of whole grains and providing meal plans and recipes that are well-balanced. But I am less fond of the first phase of the South Beach Diet, where it is a strict avoidance plan, characteristic of a fad diet.”

In fact, dietitians warn against any diet that eliminates entire categories of foods. “A person could end up being deficient in the nutrients that food group provides,” notes Cindy Martin, an outpatient dietitian with Mercy Bariatric Center. For instance, if a plan eliminates all grains, the B complex vitamins (riboflavin, niacin and thiamin) could be missed, which help promote a healthy attitude and appetite, she says.

Diets that require supplement use are another red flag for Martin. “Any plan that requires purchase of special food or supplements should be scrutinized,” she says. “Supplements do not have regulation oversight for content, cleanliness or effectiveness. The majority of nutrition supplements are not considered food, so they fall outside the jurisdiction of the Food and Drug Administration.”

Another danger of fad diets is the likelihood of losing and gaining weight, yo-yo style. “Fad diets usually end up slowing down one's metabolism and causing more weight regain in the end,” says Deanna Miller, a clinical nutrition manager at Missouri Baptist Medical Center. “People should ask themselves, Can I eat this way for the rest of my life? If not, then it’s not for them.”

So what can we do to lose weight in a healthy, sustainable way? Dietitians agree that it comes down to a well-balanced diet—consumed in moderate portions—and paired with regular physical activity.

Durbin provides specifics: “When choosing a diet, look for those that are well-balanced in the food groups so that they can provide adequate nutrients for good health. Combining healthier food choices—such as more fruit and vegetables, as well as moderate amounts of lean protein and whole grains—will provide a well-rounded diet to promote good health. There are no magic foods. Losing weight and keeping it off requires effort to change eating habits and include physical activity on a daily basis.” She also emphasizes the importance of talking with your primary-care physician about any dietary or activity changes.

One tactic that has been found successful in clinical studies is maintaining a written or online food and exercise diary. Many people find this practice makes them more mindful of what and how much they eat. Specific guidance and meal-planning is available from registered dietitians, and your physician can refer you.

“Making a commitment to any weight loss plan can be a challenge. Often, small changes add up to big differences over time,” Martin says. “A one- to two-pound weight loss each week can be achieved by cutting back food intake by 500 to 1,000 calories a day. This could be by passing on a sugary beverage, snack cake, dessert or candy bar. Switching to low-fat, low-calorie choices, such as fruits and vegetables, is a healthier option. Over time, the higher-calorie items will not be missed, and neither will the extra weight on the scale.”

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