Why your diet should include more fat

Think back to the '80s and '90s when buying anything that didn't don a low-fat label was simply taboo.

Back then, butter and egg yolks topped the "do not eat" list, while refined carbs and packaged foods weren't given a second thought. But times have definitely changed.

These days, experts tout fat as a must-have macro and full-fat products, like whole milk, avocado, ghee and coconut oil, join the ranks of superfoods.

Yet, some people still question what kinds of fat they should eat and exactly how it affects the body. That's why we called on Mark Hyman, MD, author of the "Eat Fat, Get Thin Cookbook," to help us wipe clean the greasy mess of info and lay down the facts on fat.

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5 Myths About Fat — Debunked

1. Myth: Fat on my plate equals fat on my body.

Reality: Even though this myth is the basis for low-fat diets and food products, it's far from the truth. Eating fat won't make you fat. Completely eliminating or limiting fat from your diet can actually make you gain weight, often because it leaves you feeling so deprived. Conversely, some studies have found that fatty foods can aid in weight loss.

"The problem with most diets is that they lack the key ingredient that makes food taste good and cuts your hunger," says Dr. Hyman. And you guessed it, that's fat. "Healthy fats are the best source of energy for your body, and they keep your metabolism and fat-burning mechanisms running as they're meant to," Dr. Hyman explains.

Research supports this, showing that a low-fat diet could slow down metabolism. So now you have permission to enjoy a spoonful of nut butter with an apple before your next workout or a satiating piece of steak for dinner every once in a while.

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2. Myth: Saturated fat should get a big fat "I'll pass."

Reality: Not so fast. While saturated fat has long been known as public health enemy number one, recent research proves it's not so scary. Of course, you shouldn't always opt for a meal full of red meat and butter, but having them occasionally won't wreck your health (or your waistline).

In fact, Dr. Hyman whips some butter into his coffee in the morning. Although it's higher in saturated fat, he says butter is a more wholesome ingredient, particularly the grass-fed variety.

What's worse than eating high-fat foods: replacing them with loads of sugar. Refined carbs can increase your chances of developing coronary heart disease and diabetes.

3. Myth: All fat causes health problems.

Reality: Eating different sources of fat can actually boost your health. Omega-3 fatty acids (those found in fish and some nuts and seeds) can help strengthen your heart and possibly your mental well-being, too. And the monounsaturated fats in olive oil (as well as nuts and avocados) can also cut your risk of heart disease.

Dr. Hyman has even seen some of his patients reverse type 2 diabetes by eating a high-fat diet.

4. Myth: High-cholesterol foods raise your LDL cholesterol levels.

Reality: Previous thinking also cautioned against foods high in cholesterol (a type of fat), but that's no longer the case. Dietary cholesterol doesn't necessarily raise the "bad" cholesterol levels in your body, Dr. Hyman explains. Instead, it can elevate HDL or the "good" kind.

One caveat: Trans fats and linoleic acid (found in vegetable oils) can harm your health. So steer clear of partially hydrogenated and hydrogenated oils, like canola, as well as packaged foods like cream-filled candies, frozen pizza and margarine. Sometimes, the nutrition label doesn't show trans fat, so look for hydrogenated oils on the ingredients list.

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5. Myth: Fat will keep me from my fitness goals.

Reality: Some endurance athletes actually embrace what's known as the ketogenic diet. This plan involves getting about 70 to 75 percent of your daily calories from fat and just five to 10 percent from carbs. Though researchers are still looking into the proven (dis)advantages of the diet, it can help your body adjust to running off fat stores, rather than carbs, explains Pam Nisevich Bede, RD, dietitian with Abbott's EAS Sports Nutrition.

(The mechanisms for this work similarly to intermittent fasting: When you run out of glycogen for energy, your body turns to other sources, like fat.) "Since most of us exercise to burn off that internal fat storage, it can be a win-win," Bede says.

The typical high-fat foods in a ketogenic diet aren't cheeseburgers and fries, though. It's more like avocados, fish, peanut butter, meat and eggs. Note that it also takes the body about three to five weeks to adapt to a low-carb, high-fat diet, especially if you regularly chow down on foods like pizza and pasta. And because your body digests fat more slowly than carbs (like bagels), it keeps you fuller for longer and provides a steadier source of energy levels to help you power through a long run or fitness class. If you do have a high-fat meal, wait about two hours before working out, Bede says.