Fat often gets a bad rap. If you’ve dieted at some point in your life, chances are you’ve tried going low-fat—after all, low-fat was all the rage for a while there. Nowadays, however, we’ve updated our understanding of fats. We know that certain types of fat are actually good for you—and that they do a lot for your body, from cushioning your organs to controlling your temperature to absorbing fat-soluble vitamins (A, D, E, and K), according to research from the University of Virginia Medical School. In fact, it turns out that not getting your fill of the good fat every day could actually lead to some scary health issues.
First, it’s important to understand how fat works in your body.
“Good” Fats vs. “Bad” Fats
On the good side, you’ve got polyunsaturated fats and monounsaturated fats. On the not-so-good side, you’ve got saturated fats and trans fats.
Polyunsaturated fats and monounsaturated fats help reduce levels of bad cholesterol in your blood, according to the American Heart Association (AHA). In fact, research has shown that both types of good fat can reduce your risk of heart attacks and cardiovascular disease, says Vanessa Rissetto, R.D.
On the flip side, trans fats (which are found in fried foods and many baked goods) and some saturated fats (which are most commonly found in foods like fatty beef, pork, butter, and cheese) can raise your cholesterol. (It’s worth noting, though, that some saturated fats, like those found in coconut oil, can raise your HDL or ‘good cholesterol.’)
Where To Get Those Good Fats
Two types of polyunsaturated fats you’ve probably already heard of: omega-3 and omega-6 fatty acids. Since your body doesn’t produce them on its own, you’ll need to get them through your diet. You can find omega-3s in walnuts, flax seeds, and salmon, while you can find omega-6s in eggs, poultry, nuts, and pumpkin seeds, says Rissetto.
Meanwhile, you can find monounsaturated fatty acids in nuts, seeds, and high-fat fruits like olives and avocado, she adds. (Guac, for the win!) Just keep portions in mind, says Rissetto. A serving of fat equals about a tablespoon of olive oil or a fourth of an avocado, for example.
Related: 7 Fatty Foods That Are Good For Your Health
Even good fats have their pitfalls, though. Research published in BMJ suggests that there could be a link between excessive omega-6 consumption (relative to omega-3 consumption) and increased risk of heart disease. Plus, too many omega-6s can actually promote inflammation, says Rissetto, so you’ll want to watch your intake.
The National Institutes of Health (NIH) recommends adult men get 1.6 grams of omega-3s and 17 grams of omega-6s per day and adult women get 1.1 grams of omega-3s and 12 grams of omega-6s per day. As far as monounsaturated fats go, there’s no specific recommended amount.
The United States Department of Agriculture’s Dietary Guidelines for Americans advises getting less than 10 percent of your daily calories from saturated fats and swapping in polyunsaturated fats and monounsaturated fats for saturated fats as much as possible.
What Happens When You Go Too Low-Fat
If you’re still not convinced that healthy fats should be a part of your daily grub, the following facts—all effects of eating too little fat—may inspire you to update your grocery cart. Here’s what might happen if you keep living the low-fat life:
1. You’ll put yourself at an increased risk for diabetes and heart disease. Think about it: Noshing on good fats helps cut your risk of cardiovascular problems—so if you don’t get enough of them, you’re missing out on some legitimate heart benefits, says Rissetto.
2. Your blood sugar may pay the price. When you decrease your intake of saturated fats and up your intake of monounsaturated fats, you may even be able to improve your sensitivity to insulin, a hormone made in the pancreas that regulates your blood sugar levels, says Rissetto. When your body isn’t sensitive enough to insulin, it reacts by producing even more of it, which can lead to type 2 diabetes down the line.
3. You’ll feel really hungry all day long. Fat actually keeps you full for longer, since it’s harder than sugar for your body to break down, says David Greuner, M.D., managing director and co-founder of NYC Surgical Associates. Fat also helps inhibit ghrelin, the hormone responsible for hunger, he says.
4. Your energy levels will be all over the place. When your blood sugar spikes and then dips rapidly—which happens when you eat carbs, since they are full of sugars—you cycle through bursts of energy and subsequent crashes. “When you eat a little fat, though, your blood sugar stays even for a much longer period of time,” says Greuner. And that stability will keep you going full steam ahead.
5. You may have trouble concentrating. Per the University of Maryland Medical Center, there is a high concentration of omega-3s in your brain, so they play a crucial role in your ability to concentrate and memory function. According to a study published in the journal Neurology, when people stuck to a Mediterranean diet (which is full of foods that contain omega-3s, like fish and seeds), they experienced fewer instances of cognitive impairment over the course of about four years.
6. Your skin may feel dry and itchy. Although rare in healthy adults, there is such a thing as essential fatty acid deficiency (EFAD), says Rissetto. Essential fatty acids may contribute to skin health, so one of the symptoms you might deal with if you don’t get enough is a dry, scaly rash, according to Oregon State University’s Linus Pauling Institute. (Other symptoms include decreased immunity and poor wound healing.)
You’re at a higher risk for EFAD if you have a GI condition (such as inflammatory bowel disease), which might make it harder for your body to digest fats, according to the University of Virginia Medical School.