Fats: Friend or Foe?


Creamy, chewy, delicious, deadly. Fats of all kinds have been nutritional boogeymen for decades. However recent research suggests that, not only are fats important as part of a healthy diet, but they may have special value for active athletes. So before you drench your salad with another “lite” dressing—or pile your plate with crispy bacon—get the skinny on what fats can (and can’t) do for you.

What is a Fat?

Chemically speaking, fats are made up of groups of fatty acid chains attached to a central molecule of glycerol, a colorless sugar alcohol. While our bodies can synthesize some of these fatty acids from other food sources, two of them—linoleic acid and linolenic acid—are essential fatty acids that must be obtained directly from food.

Fats play a variety of critical roles in the body, including aiding the absorption of fat-soluble vitamins such as A, D, E, and K. (See “Micronutrients, Mega Benefits” in the October 2015 issue for more details.) They’re used to build cell membranes and to regulate blood pressure and immune response. They also provide concentrated source of energy, containing twice as many calories per gram as proteins or carbohydrates. It’s this energy-dense quality that has given them their bad rap as contributors to obesity.

Good Fats, Bad Fats?

Not all fats are created equal, however. Saturated fats are typically of animal origin and solid at room temperature. (Think butter, bacon fat, and coconut oil.) Mono- and polyunsaturated fats, such as olive oil and avocado, typically come from plant sources and are often liquid at room temperature. (The terms “saturated” and “unsaturated” refer to the kinds of chemical bonds in the fatty acid chains.) To further complicate the issue, trans fats are unsaturated fats that have been chemically hydrogenated to make them solid and shelf-stable. These “Frankenfats” are universally unhealthy and are being gradually phased out of the American food supply. In the meantime, avoid any food with hydrogenated oils listed among its ingredients.

Saturated fat has long been tagged as a nutritional no-no, with increased consumption being linked to heart disease and stroke. While the American Heart Association still recommends limiting your intake of saturated fats, other researchers point to their potential benefits:

  • Stronger bones. Saturated fat is required for the effective incorporation of calcium into bone. Female and senior endurance athletes, who are at special risk of osteoporosis or bone fracture, should make sure to get plenty of saturated fat along with supplemental calcium.
  • Cardiovascular health. Sound counterintuitive? Higher saturated fat intake is associated with higher HDL, or good cholesterol, numbers. One study showed that it also cuts levels of lipoprotein (a), a substance that increases the risk of heart disease.
  • Brain boosting. The brain is made primarily of fat and cholesterol, and many important signaling mechanisms in the nervous system depend on saturated fats to work properly.

While the jury is still out on how much saturated fat is too much, rest assured that you’re probably doing a good thing for yourself by spreading real butter in your toast and enjoying full-fat cream in your coffee.

That Full Feeling

One critical role of dietary fat is regulating satiety: the feeling that you’ve had enough to eat. Low-fat diets tend to be low in satiety as well, leading to overconsumption of high-carb snacks. (Think of how easy it is to binge on candy or pasta, versus how quickly a nicely marbled steak fills you up.)

Additionally, fat-rich meals provide better regulation of blood sugar and insulin than either carbohydrate- or protein-rich foods. This regulation is critical for people with Type I or Type II diabetes, but even those without blood sugar issues can avoid the sugar rush/crash cycle by including fatty foods with a meal.

Making Fats Work for You

Glycogen, a form of carbohydrate stored in the liver and muscles, is the body’s
primary fuel during exercise. But these reserves are quickly depleted in endurance competition, and the result is the proverbial “hitting the wall.”

Sports nutritionists have found that you can actually train your body to break down fat for fuel more efficiently. A 2009 study learned that this process is fostered by a high-protein, high-fat, low-carb diet. Put its power to work for you by eating a fat-rich diet in the days and weeks leading up to a major event, then switch to high-carb foods just before the competition. You’ll burn fat as fuel more efficiently and spare your glycogen reserves for later in the race when you need them most.


About Author

Molly writes about fitness and nutrition from her home in Portland, Oregon. When she’s not at her desk, you can find her teaching history, hiking the Gorge, or hitting the archery range.

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