“Sixty percent of the human brain is comprised of fat,” says Longwill. Fat (or lipids) make up the lipid bilayer that surrounds all the cells in the body and the nerve cells in the brain. “We need fat and cholesterol for brain development,” says Carpenter. “Fat is food for the brain.”
Fat and your nutrients
If you’ve ever heard the term “fat-soluble” vitamins, then the name says it all: Without fat, the vitamins A, D, E, and K cannot be efficiently absorbed and utilized. According to Dr. Mary Enig, Ph.D and author of Know your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils, and Cholesterol, “A low-fat diet can very easily become a vitamin-deficient diet, in part because these vitamins are only found in the fatty (or oily) part of food.” And, not absorbing these vitamins can have dramatic consequences that affect everything from your reproductive system to your ability to burn calories and stave off wrinkles. (So, the next time you slug down one of those $9 green juices, throw in a little bit of coconut oil.)
Fat and your skin
If you suffered through middle school, high school, or last Tuesday with acne or you’re starting to see those crow’s feet creeping up, you might be familiar with Retinol or Retin A — prescription creams containing retinoids, the synthetic form of vitamin A. This is because vitamin A has been shown to help clear skin conditions like acne, psoriasis, and also treat premature aging. People on a low-fat or no-fat diet will have difficulty getting vitamin A says Carpenter. Lack of fat in the diet will also cause the cell membranes to literally become wrinkly, says Orlando, which can translate into wrinkly, sagging skin. “Younger and younger women are having wrinkle issues and using Botox to try to counter them, when all they need is to eat healthy fats,” she says.
Fat and your metabolism
Fat will not make you fat. Repeat: Fat will NOT make you fat. This is another statement echoed by all three experts. Unless, that is, you eat it in excess. “Anything in excess will create fat,” says Orlando. However, short- and medium-chain fatty acids like coconut oil and grass-fed butter are almost never stored as fat — they go directly into the blood stream and are burned for fuel, says Carpenter. Because both of these fats are quickly converted to energy, they actually speed up the metabolism! But, that’s not all — butter contains butyric acid, which is crucial for large intestine health, helping to promote good gut bacteria. Meanwhile, coconut oil contains lauric acid, which, according to Longwill, can increase good cholesterol, energy, and endurance. Some people believe it can also help to hasten recovery from a viral infection, like the flu or a cold sore breakout.
Fat and your appetite
Fat is digested slowly, meaning the stomach empties more slowly when you eat foods with higher fat content. This allows you to feel fuller longer. Additionally, the presence of fat in the small intestine produces the hormone cholecystokinin, which acts as a hunger suppressant. But, bodies on low-fat diets will keep sending hunger signals. “You can eat all the calories you need for the day and still be starving at a cellular level” says Orlando. “A careful balance of fat in the diet becomes critical for someone trying to lose weight,” says Enig. So, we actually need to eat fat to lose fat. Now that, Ms. Tingle, is what you call irony.
Fat and your hormones
Our sex hormones, estrogen and progesterone (which regulate libido and the menstrual cycle) and our steroid hormones, cortisol and adrenaline (which regulate stress and energy levels), are all built on a backbone of cholesterol, says Carpenter, who is also a specialist in women’s hormones. A low- or no-cholesterol diet impairs the body’s ability to manufacture these hormones and have been linked to health problems like mood and sleep disorders, adrenal burnout, infertility, polycystic ovarian syndrome (PCOS), and even extreme PMS symptoms that are becoming more and more common.
Wait — cholesterol is good for you?!?
Although not technically fat, cholesterol is referred to as a “fatty substance” that’s “essential to life,” says Enig. Cholesterol is not only necessary to manufacture hormones, it’s also a potent antioxidant, scavenging free radical cells, says Orlando. It helps give the cell membrane the proper rigidity, it’s needed to convert vitamin D into its active form, and it helps the body heal as a component of scar tissue. To Orlando, if you take away one thing about fat, it’s to understand the importance of cholesterol.
Saturated fat you say?
You may want to sit down for this, but saturated fat is also not the dastardly deliverer of health problems it’s been believed to be. Even Dr. Oz and Dr. Weil have recanted on their anti-saturated stance, after numerous scientific studies showed “no significant evidence” that saturated fat in the diet is associated with heart disease. And, according to Enig, the body needs saturated fatty acids to create at least half, and sometimes more, of the fatty-acid part of the cell membrane.
So what’s the bad fat?
Carpenter says fat is like oil in your car — poor quality fats mean poor quality functioning of everything in your body, from the cellular level up. All three experts agree the one type of fat you should never have is trans fats, which are currently in the process of being outlawed. Without getting too Bill Nye on you, trans fats are created when oils are infused with hydrogen (partially hydrogenated corn oil, anyone?) to make them more stable and have the shelf life of Methuselah. When you eat these “Frankenfats” most commonly found in processed packaged foods, they deform your cell membranes and ultimately alter how your body functions.
What’s the best fat?
Orlando says no fat found in nature is bad. Monounsaturated fats, polyunsaturated fats, and saturated fats are all good for you, the key is to have the right balance, and here’s how to get it:
Sources: organic, cold-pressed coconut oil, responsibly sourced palm oil, grass-fed butter, beef tallow, or lard
Best used: cooking at heat above 275 degrees
Sources: organic, cold-pressed olive oil, and avocado oil
Best used: cold or at low-medium heat
Sources: organic, cold-pressed flaxseed oil, wheat germ oil, walnut oil, hempseed oil, wild-caught cold-water fish like sardines and salmon
Best used: cold — never heated
Sources: organic, cold-pressed black-currant seed oil, evening primrose oil, borage oil
Best used: cold – never heat
The moral of this story is that it’s time to start using the F word on the regular. And, the best part about it? Fat is a health food that actually tastes good. Hallelujah — pass the butter and bon appetit!