Good Fat, Bad Fat

Not all fats are created equally. Learn which ones are best for your joints—and your overall health.


A few years ago, “fat” was something people were told to avoid. Today, fat is no longer the dietary bad guy. In fact, certain fats are essential to a healthy eating plan. By choosing your fats wisely, you might reduce inflammation throughout your body, which could help with your arthritis.

Good Fats

The two good-for-you fats are polyunsaturated and monounsaturated fats. These fats are liquid at room temperature.

  • Polyunsaturated fats include omega-3 fatty acids, found in fish, flaxseeds, walnuts and canola oil; and omega-6 fatty acids found in soybean, corn and safflower oils.
  • Monounsaturated fats are found in nuts, seeds, olives, vegetable oils and avocados.

Omega-3s in particular are worth adding to your diet. They have the potential to reduce inflammation, lower unhealthy low-density lipoprotein (LDL) cholesterol, and lessen the risk of heart disease.

“Our body cannot make omega-3s. That’s why they are considered an essential nutrient that needs to come from our diet,” says Christine McKinney, RD, a clinical dietitian at Johns Hopkins Bayview Medical Center. The best dietary source is fatty fish like salmon and sardines, which are high in the omega-3s EPA and DHA. 

“People with arthritis should be eating fish at least two to three times a week,” advises Kim Larson, RDN, registered dietitian and nutritionist based in Seattle, WA, and Academy of Nutrition and Dietetics spokesperson. If you don’t like fish, you can get the omega-3s you need from a supplement, but check with your doctor on the dose.

Plant sources like walnuts and flaxseeds contain another type of omega-3 fatty acid, called ALA. However, the body must convert ALA into EPA and DHA, which it doesn’t do very effectively.

Bad Fats

Two types of fats should have little to no place in your diet:

  • Saturated fats are found in meat, butter, and cheese. They stay solid in room temperature.
  • Trans fats are created when hydrogen is added to vegetable oil. This process keeps the oil solid at room temperature, and helps foods like cookies, cakes, and potato chips stay fresh on store shelves longer. You’ll find trans fats in baked goods, fried foods, and margarine.

In contrast to omega-3s, saturated and trans fats have been linked to pro-inflammatory processes in the body. They raise LDL cholesterol and block the beneficial effects of healthy high-density lipoprotein (HDL) cholesterol, which might influence heart disease risk. “People with arthritis are more at risk for heart disease, so they need to be watching that,” McKinney says. The best strategy is to get less than 10 percent of your daily calories from saturated fats and avoid trans fats as much as you can.

There might be one exception in the saturated fat category—coconut oil. This plant-based form of saturated fat has gained popularity in recent years, and animal studies published in 2014 and 2015 have suggested it has anti-inflammatory properties. Unlike other saturated fats, which consist mainly of long-chain fatty acids, coconut oil is made mostly of medium-chain fatty acids. The difference? Long-chain fatty acids tend to deposit in fat tissue, whereas medium-chain fatty acids travel to the liver, where the body burns them off. While you don’t want to overdo it on coconut oil, it might be worth adding—in small quantities—to your diet. “I think including a little saturated fat from a healthy source like coconut oil is fine, but that shouldn’t be your main fat,” McKinney says.

Don’t Splurge

Even the best fats are high in calories. One tablespoon of oil contains 120 calories—about the equivalent of eating one slice of bread, McKinney says. Getting too many calories per day can tip the scales against you. “When your weight goes up, you’re putting more stress on your joints.”

To harness the flavor and health benefits of omega-3 oils without loading up on calories, use an oil sprayer when you cook or bake. And limit the total amount of fat you eat to less than 35 percent of your daily calories.

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