Nutrition 101: Fat

By Steve Baldwin, MS, RD

The most misunderstood nutrient of them all? Fat.

It’s demonized in the media, in doctor’s offices, and in the “diet food” section of your grocery store. The government says that most Americans could stand to eat less…which is tricky, because it makes food taste so good. Remove the fat, and often times the food tastes only slightly better than the box it came in.

But the truth is that not all fats are created equal. Some types of fat should be limited, yes. But others should be a regular part of your healthy diet, and can actually help protect your body from illness. So let’s separate fact from fiction about the nutrient we love to hate: fat.

First, the basics. Fat plays several important roles in the body. Some fats are essential, meaning that your body needs them but cannot make them, so they must be included in the diet to prevent a deficiency (symptoms of essential fatty-acid deficiency include dry, scaly skin and brittle hair).

Fat provides energy that can be used by your muscles to do work. Gram for gram, fat provides more than double the amount of energy compared to carbohydrates or protein. This is one of the reasons we’re told to eat less – after all, more fat equals more calories. But like protein, fat helps keep you feeling fuller, longer. Including a little fat and protein with breakfast for instance (like adding peanut butter to toast, or having a scrambled egg on your bagel) can help keep you full until lunchtime.

Fat also helps form tissues in the body. The wall of every cell in the body is made from fat in the form of phospholipids. Other phospholipids work as hormones, providing signals related to the inflammatory response and immunity. Other fats form cholesterol, which carries fat-soluble nutrients (such as the fat-soluble vitamins A, D, E, and K) to body tissues. Although fat is an essential nutrient, some types of fat are healthier than others. The most basic single unit of fat – the fatty acid – is a chain of carbon molecules strung together like a necklace. It comes in two forms: saturated and unsaturated. They are classified as one or the other, depending on whether each carbon in the chain is filled (or saturated) with hydrogen. The carbon chain of a saturated fatty acid is holding all the hydrogen is can. Like a sponge that can’t hold any additional water, the carbon chain of a saturated fatty acid can’t take on any additional hydrogen.

Saturated fats generally come from animal sources, such as meats (e.g., red meat, poultry, bacon, sausage), dairy fats (e.g., whole milk, cream, butter, cheese), and egg yolk. Because these foods come from animals, they also contain cholesterol. Americans consume more than their fair share of saturated fat, which is linked to elevated blood cholesterol levels. Unlike saturated fats, unsaturated fat is not carrying all the hydrogen it can, but instead has some gaps that are filled by two carbons in the chain holding on to one another with a “double bond”. If the fatty acid has one double bond, it is said to be monounsaturated. Fatty acids with two or more double bonds are considered polyunsaturated.

These mono- and poly- unsaturated fats are great for your body. They help your blood vessels dilate, keeping blood pressure down and allowing blood to flow more freely. They also signal your liver to make less low density lipoprotein (LDL), which is the fraction of cholesterol that is linked to clogged arteries and heart disease.

The best food sources for unsaturated fats are plant foods, including vegetable oils (e.g., corn, olive, and canola), nuts (e.g., walnuts, almonds, pistachios, peanuts), and avocadoes. Because these foods are from plants, they are naturally cholesterol-free. Cold water fish like salmon and tuna are also good sources of heart-healthy unsaturated fats.
,br> Another type of fat that bears mentioning is Trans fat, which has garnered a lot of media attention in the recent past. Most Trans fats are man-made, although tiny amounts are present in red meats and full-fat dairy. They are shelf stable, meaning they can be used to lengthen the shelf life of baked goods like cookies, crackers, and pie crust.

But Trans fat has a huge downside: It not only raises the aforementioned LDL, but it also lowers high density lipoprotein (HDL), which is protective against heart disease. This double-whammy for your heart has led some scientists to suggest that the only safe amount of Trans fat in the diet is “zero”.

So, the bottom line when it comes to fat: reduce the foods in your diet that are high in saturated and Trans fat, and replace them with foods high in mono- and poly- unsaturated fats.

It’s not hard to put into practice. Eat less red meat, remove the skin before cooking chicken or turkey, and aim for eating fish twice a week. Bring nuts to work as a hearty (and heart-healthy) mid-afternoon snack. Add avocado to your next sandwich, instead of mayonnaise. Switch to a lower fat milk products, and read food labels to limit Trans fat as much as possible. Your body, especially your heart, will be glad you did.


Steve Baldwin, MS, RD lives in Long Beach, California with his wife, three kids, two dogs, and a kitchen full of delicious foods. He can be reached at wordstoeatby@yahoo.com.
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