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The Rumor: Fats make you fat

Fats in our diet used to get a bad rap. But for a while now, we’ve been hearing that there are such things as “good” fats, which seems rather befuddling. Should we really be eating “good fats," or should we shun lipids of all types?

The Verdict: Some fats really are good for you

The idea that all fatty foods are bad for you should go the way of leg warmers, shoulder pads and “The Safety Dance.” In other words, avoiding fats is an outdated idea that just doesn’t belong in the healthy here and now.

“The persistent myth is the idea that we should be avoiding fatty foods altogether,” says Tanvir Hussain, MD, a cardiologist at St. Francis Medical Center in Los Angeles. “I sometimes think these people are stuck in the ’80s, which is the last time I heard low-fat was good for anything. The research has gone way beyond that, to show what we need are the right type of fats... not necessarily less of them.” 

In other words, all fats are not created equal. Different types will have good or bad effects on not only your waistline, but your arteries, heart and even your mood -- so knowing the difference between them will affect more than the notches on your belt loop. 

“The only truly bad-all-the-time, no-redeeming-qualities fat is man-made trans fat,” says Jonny Bowden, Ph.D., CNS and author of The Great Cholesterol Myth“You can't even say that all trans fats are bad, since natural trans fats found in the meat and milk of ruminants -- for example, CLA in cow's milk -- are actually good for you. But man-made trans fat is really bad stuff.”

Indeed, a recent study published in the American Journal of Clinical Nutrition found that natural trans fats, which are found in beef, lamb, pork, butter and milk, for example, don’t seem to be as harmful as their man-made counterparts.

It’s the latter you wouldn’t want to meet in a dark alley -- or, for that matter, a wide, brightly lit supermarket lane. 

The reason they’re called “trans” fats is that fatty-acid chains are formed when manufacturers turn liquid oils into solid fats via a process called hydrogenation. Hydrogenation is used to create trans and saturated fats and increases the shelf life and flavor stability of foods. That's why some of the worst offenders are spreads like margarine and packaged foods such as cake mixes, as well as fast food, frozen foods, commercial baked goods, chips, crackers, cookies and candy. (Sorry, sweet tooths.)

Unfortunately, trans fats also live a long, happy life clogging our arteries, which can pave the way to heart disease.

The best approach is to look closely at labels and avoid foods that contain partially hydrogenated or vegetable oils, which often contain trans fats. Experts agree that the further away you stay from these bad boys, the better off you’ll be.

Which brings us to the good fats -- and here’s where we get to the root of a lot of the confusion: We need fats in our diet, and some fats actually promote good health.

“What we call ‘good fats’ are essentially unsaturated fats,” says Hussain. “Saturated fat is called ‘saturated’ due to its chemical structure.” (He’s referring to all the hydrogen atoms involved in hydrogenation.) Unsaturated fats, on the other hand, are not saturated with hydrogen atoms, which results in a more pliable chemical structure. “That’s what we want to happen in the body,” he explains. “You want your arteries to remain soft and pliable.” Unsaturated fats are commonly found in foods like fish, nuts, avocados and olive oil.

Then there are the fats that are especially good for you. You’ve probably heard the term “omega-3” thrown around, right? These essential fatty-acid chains -- so-called because human bodies don’t produce them, so we have to get them in our diets -- are found in foods like salmon, walnuts, flax seeds, grass-fed beef, shrimp and tofu, and are believed to do everything from reduce inflammation to increase the production of “good” cholesterol (aka HDL).

One type of omega-3, ALAs, are also found in green, leafy vegetables such as Brussels sprouts, kale, parsley and spinach, as well as in chia seeds and kiwi. They're nutritional superstars that are becoming increasingly available, with grocery store aisles brimming with staples such as orange juice that’s fortified with omega-3s.

“Omega-3s are anti-inflammatory, lower blood pressure, lower triglycerides and improve mood,” says Bowden. “Virtually everyone could benefit from more omega-3s in their diet.”

The Fat Bottom Line

While America may still be suffering from "fat phobia," nutritionally speaking, most fats aren’t the enemy. “The role of fat in the diet is absolutely essential,” explains Bowden. “You would live just fine on protein and fat with no dietary carbohydrate, but you would die with just dietary carbohydrate and no dietary protein or fat. Fat is needed for storage of energy, for cushioning of the organs, for fuel, for survival… period. It's absolutely essential for life.”

But before you run off and bear-hug the nearest unsaturated fat, there is one caveat: “While good fats should make up a greater proportion of the diet than they do now,” says Hussain, “one still would have to watch the total calorie intake.” Translation: While the fats in avocado may be good for you, that doesn’t give you license to eat your weight in guacamole. Overall, the FDA recommends that between 20 and 35 percent of your daily caloric intake come from fats. 

So, how do you manage your fat intake and get enough of the good stuff without going overboard on calories or eating unhealthy processed foods? Try these tips:

Shop The Perimeter. Of the store, that is. This is typically where grocers stock the freshest foods, like fruits and veggies. By passing up the middle aisles, you’ll be more likely to avoid coming face-to-face with tempting trans fats. 

Up Your Omegas. Try to eat omega 3-rich fish like salmon, herring or sardines at least once a week. Not a seafood lover? Stock your favorite snack drawer with walnuts -- which, ounce for ounce, boast more omega-3s than even wild salmon.