Years ago, nutritionists cautioned individuals to steer clear of “fattening” foods on a list that included nuts, seeds, avocados and olives. But eventually, findings showed that these plant-based foods as well as oily fish, such as salmon, sardines, mackerel and tuna—all rich in omega-3 fatty acids—are good sources of healthy monounsaturated and polyunsaturated fatty acids, which lower the risk of cardiovascular disease and type 2 diabetes.

According to the American Heart Association, the body needs dietary fats for energy, cell growth, regulation of body temperature, nutrient absorption, hormone production and protection of the vital organs, such as the kidneys, heart and intestines.

The avocado is the fattiest fruit. Nearly 85 percent of its total calories are from fat, surpassing the olive, which also contains healthy fat. “While fat is often regarded as a bad word, not so when it comes to the avocado,” says Ian K. Smith, MD, in his book The Clean 20: 20 Foods, 20 Days, Total Transformation.

These fatty foods help lower levels of LDL, or bad cholesterol, and provide a host of vitamins, minerals, fiber and other phytonutrients, Smith adds.

But to avoid excess calories, be sure to eat these healthy fats in moderation.