The Fat Truth

The Fat Truth

Fat is on the radar again. It’s gone from being banished in the ’90s in the name of heart health to making a comeback with a recent media frenzy touting the virtues of saturated fats like butter.

The low-fat trend became popular largely due to a groundbreaking 1990 study, The Lifestyle Heart Trial, by cardiologist Dean Ornish, MD. This was the first randomized clinical trial to look at whether people could make and sustain lifestyle changes and, as a result, reverse coronary atherosclerosis (hardening of the arteries) without lipid-lowering drugs. The study worked. The subjects had a reversal in severe cardiac blockages after one year of following a low-fat diet plan; however, the plan encompassed a whole lifestyle approach beyond just limiting the fat in their food.

“The low-fat diet lifestyle is more than just low fat; it’s a comprehensive approach, which involves eating a largely plant-based diet with limited animal products and it emphasizes regular exercise, social support and stress management,” explains Bethany Doerfler, MS, RD, clinical research dietitian in the Division of Gastroenterology at the Digestive Health Center at Northwestern Medicine.

The low-fat message was muddled, however, resulting in high production and consumption of sugar-laden, empty-calorie food products—think SnackWell’s cookie craze—that arguably led to obesity and other chronic diseases rising in the United States.

“Americans heard ‘low-fat’ and simply took to fat-free eating, which meant a lot of refined sugars and excess calories,” Doerfler says. As a result, the Americanization of the low-fat message increased triglycerides (blood fats) and decreased the good cholesterol or high-density lipoproteins (HDL)—both risk factors for cardiovascular disease (CVD).

The Fat Difference

Our bodies need fat, but not all fats work the same way inside of us. Saturated fat, which has been implicated in CVD and is found in red meat, dairy products and fried foods, has been on the public-health watch for decades.

“What is not often recognized is that there are dozens of saturated fats, and each has unique biologic properties. For example, the saturated fat in dark chocolate is stearic acid, one that doesn’t raise LDL cholesterol,” explains Stephen Devries, MD, a preventive cardiologist and executive director of the Gaples Institute for Integrative Cardiology, an educational nonprofit in Deerfield with the mission of advancing the role of nutrition and lifestyle in healthcare.

“Some saturated fats, like those concentrated in butter and meat, raise cholesterol more than others,” Devries says.

Also, artificial trans fatty acids or partially hydrogenated vegetable oils found in some store-bought baked goods should be avoided because of their detrimental effect on heart health. Trans fats are formed when hydrogen is added to liquid vegetable oil, turning it into a more shelf-stable, semisolid fat.

But not all fats are bad. For example, coconut oil— rich in another saturated fat called lauric acid—raises the bad cholesterol, LDL, as well as the good, HDL, in equal measures, according to Devries. Coconut oil is also a concentrated source of so called medium-chain triglycerides, or MCTs, that are metabolized differently from other fats and may have some beneficial properties. Similarly, eating full-fat dairy products like butter, whole milk and yogurt, and olive oil, avocados, nuts and fish help your body utilize fat-soluble vitamins A, D, E and K. Reproductive hormones like estrogen and progesterone in women and testosterone in men function better with a moderate amount of fat, both saturated and unsaturated, in the diet. Plus, full fat can be satiating and may make you feel full longer so that you eat less overall.

Unsaturated fats are best known for their role in heart health. These can be found in foods like extra-virgin olive oil, avocados, walnuts, seeds like flax, chia and hemp, as well as cold-water fatty fish like cobia, salmon, trout and barramundi.

Therefore, banishing fat is not the answer, but including foods with healthier fats in your diet is the key.

“I believe we would be far better off to think about healthy foods rather than to focus on individual nutrients. Each food is a package that contains much more than fat. It’s important to focus on the whole food,” Devries says.

The best bet for heart health is honing in on vegetables, fruits and whole grains instead of refined, sugar-laden fat-free substitutes. Plus, it’s smart to cut back on meat and replace it with fish and plant-based protein like beans, legumes, nuts, seeds and grains.

“One of the main problems with focusing on eliminating any single nutrient including fat, is that what is added is just as important as what is removed,” Devries explains. So skip the fat-free products, and focus on whole foods for health.

Fatty Fish nutrition infographic

Originally published in the Fall 2015 print edition.