Medically reviewed by Lindsey Marcellin, MD, MPH

Myth: You Should Eat Small Meals Every Three Hours

As with many other diet tips, May believes, this myth was based on observing how thin people eat, and passing their habits along as diet advice. “Many thin people do tend to eat frequent small meals,” she says. “However, most of them don’t check their watch to tell them when to eat — they eat when their body tells them to. Instead of watching the clock, learn the signals your body uses to tell you it’s hungry.” Several studies, including one recent analysis at the University of Texas, have shown that training dieters in the practice of mindful eating, or focusing on the body’s hunger cues, is an effective way to curb overeating.

If you do find that eating every few hours works for your diet, watch your calories to make sure you’re not consuming too many.

Myth: You Shouldn’t Eat After 7 P.M.

“The danger of nighttime eating is true and false,” says Melissa Dobbins, RD, a dietitian and spokeswoman for the Academy of Nutrition and Dietetics. A Northwestern University study in mice found that when the mice consumed their calories impacted weight gain. At the end of the study, mice who ate during sleeping hours gained more weight than those who followed regular eating schedules. “However, there’s no magic to the 7 p.m. time,” Dobbins says. “Losing weight is a matter of limiting our calorie intake, and most people tend to eat most of their calories in the evening, at dinner and snacking afterward. If you’re limiting your calories at night, this diet trick will probably help you.”

Myth: Drinking Eight Glasses of Water a Day Flushes Out Fat

This is another diet myth that has a grain of truth in it, but not because any fat is being flushed away. “I hear this myth a lot, but I always have to keep reiterating that there’s no magic about drinking water,” says Sue Gebo, RD, MPH, an assistant professor at the University of Connecticut School of Medicine. “It doesn’t flush away any fat.” However, a study at Virginia Tech University found that people who drank 16 ounces of water before eating consumed between 75 and 90 fewer calories than a control group. Even though all participants in the study were on low-calorie diets, on average, the water drinkers lost 4.5 more pounds than the non-water drinkers.

Myth: High-Fructose Corn Syrup Causes More Weight Gain Than Sugar

The vilification of high-fructose corn syrup has become so intense that the American Medical Association was asked to issue a warning against it but declined, citing no evidence that this type of sweetener contributes to obesity any more than standard table sugar does. The difference is that table sugar is made from one glucose molecule joined with one fructose molecule, so it contains glucose and fructose in equal proportion. High-fructose corn syrup is the same mixture, just with slightly more fructose. Because the two products have the same ingredients in roughly the same proportions, some researchers believe they affect the body similarly. However, research results are mixed — a team of Princeton University scientists recently found that rats who consumed HFCS gained significantly more weight than those who ate table sugar, even when their caloric intake was the same.

The real takeaway is that both HFCS and sugar add unwanted calories, make weight loss more difficult, and can contribute to disease risk. For long-term weight loss success, stay away from both.

Myth: You Should Follow Your Diet for Six Days and Then Have a ‘Cheat’ Day

“This is absurd,” declares May, noting that people who try to be “perfect” six days a week invariably fail because dieting perfection is impossible to obtain. Also, such a dieting edict might encourage you to overeat on that seventh day, even if you have no intention of doing so. Dobbins agrees, although she adds that for a few people, this strategy might make sense if it helps them keep on track but not if it undermines their healthy eating patterns the rest of the week.

Myth: All Refined Grains Are Bad for Dieters

Increasingly, there’s been an emphasis on eating whole grains instead of refined grains, like choosing whole-wheat bread instead of white. Whole grains contain more fiber and are metabolized more slowly than refined grains, but that doesn’t mean there is anything inherently evil about refined products as part of a smart dieting plan. Gebo says current government guidelines that suggest Americans choose whole grains half of the time make sense to her. “Why would we ever want to tell ourselves we could never have a loaf of crunchy French bread again?” she asks. “It just doesn’t make sense.”

Myth: Honey Is Better Than Sugar for Weight Loss

Honey, though it has some additional health benefits, is just another form of sugar. Both are carbohydrates and are considered “double sugars,” which refers to their type of sugar molecule. Because the two are essentially the same, they are digested at the same rate, whether you’re dieting or not. “The difference between honey and sugar is that honey does contain trace amounts of amino acids, vitamins, and minerals and sugar does not, but you would have to eat large amounts of honey to receive any nutritional benefit,” Dobbins says. In fact, honey may actually be worse for your waistline because, tablespoon for tablespoon, it has 63 calories to granulated sugar’s 48.

Myth: You Should Cut Out All Carbs to Lose Weight

Don’t be fooled by diet fads that are based on making one food group “bad” and other ones “good.” The best way to eat, even when dieting, is to create meals from all the different food groups, carbohydrates included. Carbs provide fuel for the body and power the brain and nervous system. The truth is that all types of food fit into a healthy diet, and that includes not only carbs but a certain amount of fats and proteins as well. “Since different foods have different nutritional qualities, it’s up to you to use balance, variety, and moderation in order to make up a healthy diet,” May says.

Myth: You Should Eat Only a Certain Number of Calories or Points per Day

People’s nutritional needs vary from day to day, depending on their activity levels, hormonal needs, or other bodily functions, May says. But knowing your ideal calorie intake for weight loss can still be a valuable measure. The trick is not depriving your body every single day and expecting that to be a sustainable diet. If you’re not feeding your body properly, you’ll be tempted to “cheat” on a day when you are actually hungrier, depriving your body of the nutrition you need and also never getting free of the “dieter” mentality, May notes. The takeaway is to just beware of any unrealistic fad diets that are too rigid to stick with.