here are certain health “truths” we tend to take for granted, largely because they are repeated again and again by people with letters after their names or in countless news reports or TV broadcasts. But it turns out that some conventional wisdom is more hype than help. Hers separates fact from fiction to debunk some popular health myths.

1. Eating breakfast is crucial to successful weight loss.

New thinking: While it’s true that breakfast plays an important role in your diet, it may not be the magic bullet we once thought when it comes to weight control. A review of breakfast studies published in the American Journal of Clinical Nutritionfound no clear evidence that regularly skipping breakfast also means packing on the pounds.

Keep in mind: We’re not saying to shun the morning meal altogether. In fact, if you’re active (and if you’re visiting this website, we know you are!) there are plenty of good reasons to eat breakfast. A healthy morning meal supplies the nutrients and energy you need, especially to fuel morning workouts. You just don’t have to sit down to a full-on feast shortly after jumping out of bed. Rather, the idea is to have at least a little food in your stomach before rushing out the door, says Michelle Dudash, R.D., a chef and the author of Clean Eating for Busy Families. “Eat some of your breakfast at home or in the car, and have the rest later,” she suggests. Among her favorite protein-packed portable meals: whole-wheat crackers topped with cottage cheese, blueberries, and hemp seeds. Dudash recommends stocking the ­kitchen with the basics for dine-and-dash breakfasts, including hard-boiled eggs, spinach frittata, and Greek yogurt.

2. Avoid caffeine before exercise because it’s dehydrating.

New thinking: Past fluid-­balance studies done on people who consume little or no caffeine may have initially created this long-lasting misconception. But more recent research has concluded that all beverages—even caffeinated ones—can contribute to your daily fluid needs.

Keep in mind: Caffeine can play an important part in boosting performance, helping you burn more fat, and increasing endurance while reducing perceived exertion, or how hard an exercise feels. That said, too much of this substance can backfire, causing headaches, nausea and stomach cramps. Try to get the bulk of your fluid from plain water rather than a venti double latte or extra-large iced tea, since those often provide extra calories along with lots of caffeine. And remember that if you are jittery, have trouble sleeping, or simply find yourself at a loss without a cup of coffee close at hand, it may be time to cut back a bit.

3. You need at least eight hours of sleep for good health and energy.

New thinking: Sleep needs differ, and they change with age—there’s no one set formula for everyone. Research has shown that some people need up to nine hours of shut-eye a night, while others seem to function perfectly fine on a mere six or seven.

Keep in mind: It’s not just the quantity of sleep you’re getting—quality is even more crucial. “Studies have shown that waking often during the night, which we call fragmented sleep, can affect how well a person functions during the day,” says Jodi Mindell, Ph.D., associate director of the Sleep Center at the Children’s Hospital of Philadelphia. Waking up often during the night can leave you crabby, forgetful, and worn out. The better rested you are, says Mindell, the more productive your workdays and your workouts.

While you can’t necessarily banish a partner whose snoring interrupts your slumber, there are other areas that you can control. For example, limit your food and fluid intake just before bed to avoid indigestion (and those early-morning trips to the bathroom). And avoid relying on those nightcaps: Although alcohol can help you relax, it can also significantly disrupt the quality of sleep.

4. Eating after 6 p.m. causes weight gain.

New thinking: There’s no science to support the notion that eating after a certain time plays havoc with your waistline. Yes, your metabolism slows down as night approaches, but research published in the journal Obesity shows that night eaters burn the same calories as people who don’t eat after the sun goes down.

Keep in mind: It’s OK to dine after 6 p.m. and even to indulge in that late-night supper with friends. Just remember that calories count whenever they are consumed, and if your eating window is open longer, there’s a higher chance you’re taking in far more than you burn. Consume most of your calories earlier in the day and you’ll avoid busting your daily calorie budget before you go to bed.

Also remember eating at night often triggers overindulgence as a way to cope with stress or boredom. If you need an end-of-the-day snack, budget up to 200 calories for a mini-meal that contains about 20-40 grams of protein plus some complex carbs, such as a green smoothie made with 1 small ripe banana, ½ scoop vanilla protein powder, 8 ounces fat-free milk, and 2 cups raw spinach; or ¾ cup low-fat ricotta cheese mixed with 1 teaspoon honey and 1 cup fresh or frozen berries. This kind of smart eating will help fuel your muscles while you sleep so you recover faster.

5. Food cholesterol causes heart disease.

New thinking: Cholesterol has a poor reputation that’s not entirely deserved. Research suggests only a weak link for most people between the ­cholesterol in food and artery-clogging blood cholesterol that may lead to heart disease. “Dietary cholesterol has little effect on blood cholesterol,” says Maria Luz Fernandez, Ph.D., a professor of nutrition at the University of Connecticut, Storrs. “Only about a third of individuals have an increase in blood cholesterol when they consume 600 additional milligrams of dietary cholesterol, and even when total cholesterol increases, so do levels of HDL, which protects against heart disease.” If your eating plan is packed with veggies and whole grains, which offer heart-healthy fiber, vitamins, and minerals, foods like egg yolks probably won’t cause additional harm.

Keep in mind: While the link between food cholesterol and blood cholesterol levels isn’t strong for everyone, it may matter for a small percentage of people. There’s no simple test to tell who is prone to the effects of dietary cholesterol, so if you have a family history, get your blood levels checked on a regular basis to make sure you’re always within healthy limits.

6. Daily workouts are crucial to keeping you strong.

New thinking: Everybody needs recovery time. Rest plays an important role in your exercise regimen by allowing your body to repair and strengthen itself between workouts. “It takes approximately 48 hours for the body to repair itself,” says Brad Schoenfeld, Ph.D., author of The M.A.X. Muscle Plan. “If you work out without time off, you may end up in an overtrained state, which could result in reduced exercise performance, chronic fatigue, and lower immunity.”

Keep in mind: Doing a split routine like resting your upper body while working your legs and glutes may not provide enough time for your body to fully recover. “Muscles don’t fully work in isolation, so even if you think you’re resting one area, you’re still engaging some effort,” Schoenfeld says. “Those upper-body ­muscles are still working hard to stabilize you during the performance of many leg exercises, such as squats and lunges.” Rule of thumb: Train for no more than three consecutive days without time off, says Schoenfeld, who ideally recommends two days on and one day off for either strength training or cardio.