Why you actually should be eating dessert, plus 6 other tidbits of diet wisdom you've heard over and over that aren't necessarily true.

Brierley Horton, MS, RD

Pictured recipe: Queen of Sheba Cake

Diet advice runs rampant on the internet-and, perhaps even more so, among friends and colleagues with well-meaning anecdotes and tidbits they've picked up along the way. But decades-old advice and intuition isn't always legit. We know a lot more now than we did back then. Here, we tackle the truth behind six well-known diet wisdoms and set the record straight.

Read more: 5 Ways to Help Your Diet Become a Way of Life

1. Skip dessert.

Lots of people give up their favorite foods when they're dieting. Deprivation isn't a great way to lose weight long-term, since most people can't sustain diets that cut out all the foods they actually like to eat. You don't need to give up your favorite foods to lose weight, and you don't need to cut out desserts entirely.

New research helps shed light on why dessert eaters can have their cake and eat it too. When people chose an indulgent dessert as part of their meal, they actually consumed fewer calories overall. Skipping dessert led people to think they were making a "healthy" choice and they gave themselves license to go overboard on other parts of their meal. It's called a "health-halo" effect.

It makes sense-eat what you want and you'll be more satisfied and make other healthy choices throughout the day to balance out your sweet treat. Also, when you don't restrict sweets, they won't be (or feel) off-limits and potentially more desirable.

2. A calorie is just a calorie.

If you're trying to slim down, it doesn't matter if you follow the "Twinkie Diet" or another more nutritionally well-balanced diet like the Mediterranean diet, so long as you stay below your calorie target, right? Nope, all calories are not created equal.

As cliché as it may sound, quality does legitimately trump quantity. How much you eat matters, yes, but choosing healthier, nutritious foods-like fruits, vegetables, whole grains, lean proteins, etc.-versus less-healthy foods (or so-called "empty calories") bodes better for your waistline. (Something that's deemed "empty" calories means it's food that contributes calories, but no good-for-you nutrients whatsoever, such as doughnuts, sugar-sweetened beverages, candy.)

In fact, in one study, published in the New England Journal of Medicine, people who gravitated toward less-healthy foods (think: potato chips, sugary drinks, red and processed meats) gained more weight over the course of the 20-year study than those who typically ate healthier foods.

So keep quantity in mind, yes, but aim more for quality food choices as much as possible.

Pictured recipe: Avocado Toast with Burrata

3. Eat low-fat to easily cut calories.

We've been hearing this advice for decades. Literally. (Here's a little nutrition history: a cap on total fat came into play in the 1980s in the U.S. Dietary Guidelines).

Well, in 2015 the Dietary Guidelines eliminated their recommendation to limit your total fat intake, which was welcome news, as nutrition science has evolved and we now know (with much more confidence than we did four decades ago) that those good-for-you unsaturated fats found in nuts, oils, avocado and fish are core to a healthy diet. "Adding healthy fat and decreasing starchy carbs are key factors to lose, or maintain, weight. Fat provides satiety, but what has an equal-and maybe more important-impact on cravings and appetite is avoiding the fillers filled with carbs, sugar and sodium in low-fat foods," explains Carolyn Williams, Ph.D., R.D. (Learn more and see our picks of 4 foods to choose full-fat.)

It's true; when you swap your full-fat product for a lower-fat version, it's likely (though not always the case) that your lower-fat version will save you calories, and a few grams of fat, but it likely delivers more sodium, more added sugar and possibly extra, unnecessary additives.

What's more, newer research, published in November 2018, showed that dieters who ate a lower-carb diet and replaced some of those carbs with fat actually burned more calories and were more successful in keeping off weight that they had previously lost.

4. Going low-carb is the best way to lose weight.

Yes, you did just read that eating a lower-carb diet can boost your metabolism and make it easier to maintain your weight. We're not going to contradict ourselves and now tell you that going low-carb doesn't work. If you want to slim down, low-carbohydrate diets work, folks! But eating more carbs (and dialing back on other food groups) also works. There's even research that shows following that kind of eating pattern may ever-so-slightly boost your metabolism and help you burn off more fat.

Perhaps more importantly, though, remember that good-for-you carbohydrates like whole grains, legumes, fruits and veggies are some of the leading sources of fiber in your diet. Cut those out completely and you'll also be following a very low-fiber diet, which is, well, not good. That's because not only does fiber help to keep you regular, but it also can help you slim down and keep extra weight at bay. Learn more about the 10 Amazing Health Benefits of Eating More Fiber.

Pictured recipe: Grilled Blackened Shrimp Tacos

5. A cheat meal is OK.

If you are looking forward to a cheat meal, that means whatever you are eating on the regular feels restricted, boring and unsatisfying. "That's no good because giving yourself 'cheat meals' perpetuates the idea of being good versus being bad-being on a diet versus being off a diet. And that's just not a healthy mindset," says Dawn Jackson Blatner, R.D.N., author of The Superfood Swap. "This is exactly what not to do if you really want to live a healthy lifestyle and get off the yo-yo of weight gain and weight loss," she adds. And newer research suggests that regularly yo-yo dieting (also called weight cycling, or the constant loss and gain of weight) could shorten your lifespan.

Instead, don't wait for a cheat meal to eat what you want. "Use healthy swaps to eat what you want-pizza, burgers, nachos-just use better-for-you ingredients like more veggies, whole grains and less-processed versions of your favorites," says Blatner.

Get inspired: Healthy Comfort Food Recipes

6. Don't skip meals.

You've heard this diet "wisdom" over and over again, and likely with an explanation along these lines: It'll keep your metabolism humming along (and kick-start it in the morning, which is why you shouldn't pass up breakfast). Regular meals and snacks will also prevent you from becoming ravenous and making a "bad" food choice.

"The idea that you need to eat every three to four hours is so ingrained into the concept of a healthy diet and efficient metabolism," says Williams. "I never even considered going longer stretches without eating until I started looking at research a few years ago."

But there's ample science to show that following some sort of fasting diet-be it intermittent fasting, a time-restricted diet or a religious fast-does help people eat less and lose weight. "Eating every few hours actually causes more fluctuations in blood sugar-making us feel hungrier. Turns out, research suggests metabolic rate is the same-if not slightly higher-when you fast 12 to 24 hours. And there are other benefits: no dips in blood sugar or energy; the ability to make better food choices; and the flexibility to splurge without feeling it immediately in your clothes," says Williams, who has tried intermittent fasting herself.

Intermittent fasting isn't a one-size-fits-all solution, but it may be worth exploring.

7. Grocery-shop on an empty stomach and you'll buy more.

Intuitively, yes, this resonates: if you're hungry-ish while you cruise the grocery store aisles, you could be more inclined to pick up more food along the way. And then a study was published that suggested exactly that: hungry grocery shoppers put more high-calorie food (candy, salty snacks, red meat) into their shopping carts than their nonhungry counterparts. A month later, a similar study was published. This one found that when students preordered their lunch, they were more likely to make a healthy choice. But get in that lunch line hungry and they're more likely to make a less-healthy lunch purchase.

But-big but here-both of those studies were recently retracted for lacking scientific validity. That doesn't necessarily mean that we should all always go grocery shopping when we're hangry. But if you don't have time for a meal or snack before you shop, it's OK because it might not make much of a difference. And to put it all in a bigger-picture perspective: even if the research was valid, it didn't follow up to see if those shoppers ate all of that extra food they purchased.

One grocery shopping strategy that can help you put healthier items in your cart? Make a list. That will help keep you from impulse purchases and allow you to get items you actually need for healthy meals to make at home (learn more about meal-prep strategies for weight loss here).

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