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The Skinny on Fat: How to Tell the Healthy from the Harmful
To most of us, fats are a four-letter word – the nutritional equivalent of the guy in the black hat. We tend to think of fats as the root of all dietary evil, responsible for the growing rates of obesity and type 2 diabetes. The truth is both happier and less black and white than that. Fats (note that it's a plural term) are both good and bad for you. They can help or harm your heart, and it's good to know the differences.
Fats are an important part of our diet. Our bodies can’t function properly if we avoid fats completely because fats provide important building blocks for many tissues in the body and brain (this is why no-fat diets can’t be sustained). However, eating too much fat — particularly too much of the wrong kinds of fat — is just as bad, as this can lead to significant health problems down the road, like heart attack and stroke. So it is important to become educated about the different kinds of fat and to know what a healthy low-fat diet looks like. (Hint: it does not mean loading up on carbohydrates and low-fat chips and cookies by the bag-full.)
Today our take on fats is more balanced and more accurate than it was years ago, as researchers understand more clearly the different roles that fats play in our bodies. As opposed to the diet crazes of old, most experts now recommend eating a balanced diet, rich in proteins, complex carbs, and healthy fats, like omegas and unsaturated fatty acids, which our bodies need to function properly.
We hope to clear up some of the confusion that surrounds people's ideas about fat these days. We’ll start with a break-down of the types of fats you should consume for a healthier you, as well as those you should try to avoid or eat in moderation. We’ll also discuss how the fats in your body affect the health of both your body and mind.
What Do Fats Do? How Much Do You Need?
Fats provide your body with the energy that it needs to function properly. In fact, fats are the most energy-efficient form of fuel out there, with one gram of fat providing nine calories (contrast this to both carbohydrates and protein, where one gram only provides four calories)(1). For this reason, fats are great for energy, but are also easy to consume too much of (and excess fat from food is converted to fat stores in the body, making us… well, fat).
Another function of fat is to provide the fatty acids that the body uses for building blocks for certain tissues, for example, like those that insulate nerve cells. Fats are also necessary for the absorption of fat-soluble vitamins like A, D, E, and K(2), and, as we’ll see, play an important role in keeping cholesterol levels in check, which directly influences your heart health.
The NIH recommends that adults get between 20% and 35% of one’s daily calories from fat, depending on a person’s lifestyle and activity level. Children need more fat than adults, because their bodies are still developing and require more fats for this purpose. In fact, the NIH recommends that children under 2 be given whole milk rather than skim(2), and the USDA suggests that kids between the ages of 2 and 3 should get 30-35% of their total calories from fat(3). For children 4-18 years of age, between 25-35% of their energy should come from fat. But, as we’ll discuss shortly, for adults and kids alike, the type of fats that make up your diet is as important as the total amount that you consume. In general, adults should eat healthy fats like mono- and polyunsaturated fats (like omega-3s) rather than saturated and hydrogenated fats.(4) Learning to find a balance between the good and the bad fats, as well as between fats, carbs, and protein, is an important skill, and one that gets easier with practice.
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