Considering the high-fat keto diet is currently the top lifestyle trend around, it’s safe to say we’ve come a long way since the low-fat-everything days of the ’80s and ’90s. And now that we know how essential eating fat is for overall wellness, many of us are more concerned with getting enough than with avoiding it.

Not sure whether you’re getting your proper fill of healthy fats? We asked the experts for a breakdown, including the telltale signs you should eat more of this macronutrient.

First, Why Eating Fat Matters

According to naturopathic physician Lauren Deville, N.M.D., you need fat in your diet. “Your brain is almost entirely made of fat, as are the sheaths around your nerve cells,” she says.

“It’s also necessary for healthy cell membranes, which ensures that the good stuff—nutrients, oxygen, and cell signals—can get into cells, and waste can get out.” Plus, dietary fat provides fat-soluble vitamins: vitamin A, vitamin E, vitamin D, and vitamin K, which mediate hormone activity and play other key roles throughout the body.

Dietary fat is also a great source of energy. While carbohydrates and protein contain four calories per gram, fat contains nine—so it provides the biggest bang for your buck energy-wise, explains Perri Halperin, M.S., R.D., clinical dietitian at Mount Sinai Hospital.

Current dietary guidelines from the World Health Organization and the USDA recommend we eat between 20 and 35 percent of our total calories from fat. Thing is, there are different types of dietary fat out there—and not all are created equal.

Types Of Fat

The debate about which fats our diets should consist of still rages on. In the meantime, keep these basics in mind:

• Trans fats (also known as partially-hydrogenated oils) are just plain bad. These highly processed, Frankenstein-like oils have been shown to increase bad LDL cholesterol and lower good HDL cholesterol. They also interfere with cell membrane function and negatively impact immune health.
• Saturated fats still bear an uncertain fate. These fats come mostly from animal sources, along with a few plant sources, like coconut oil. Many experts recommend limiting them to less than 10 percent of daily calories and suggest they negatively impact heart health. Recent research questions this, though, so stay tuned!
• Unsaturated fats are considered healthy fats. Monounsaturated fats (like olive oil and avocado) support healthy cholesterol, while polyunsaturated fats (like salmon) contain omega-3s, which have been shown to improve brain, immune, and heart health.

Generally, experts recommend most of your fat intake come from a variety of unsaturated fats from whole, unprocessed foods. “Go to town on the fats found in produce, such as avocados, nuts, and coconuts,” says Deville.

The American Heart Association also recommends eating walnuts and flaxseeds regularly, along with one serving of fatty fish twice a week, to ensure you’re getting enough omega-3s.

The Effects Of Eating Too Little Healthy Fats

Given our long, complicated relationship with dietary fat, many people—even health-conscious people—still risk eating too little of the nutrient. Here are four health issues that may indicate you need to eat more healthy fats.

1. You’re Hungry All The Time

If you don’t eat enough fat, chances are you don’t eat enough calories overall. And that affects all of your body functions.

Plus, it also makes you more likely to lean on carbs, which creates a chain of events in the body that lowers satiety,’ says Deville.

“When you consume carbs, your pancreas produces insulin to move it from your blood into your cells,” Deville explains. “The more carbs you consume [notably refined carbs], the faster they hit your bloodstream, the higher your blood sugar spikes, and the harder and faster it falls once that insulin is produced.” When your blood sugar plummets like this, you get hungry for quick energy (a.k.a. more carbs) and start the vicious cycle all over again. The end result: You’re never truly satisfied.

Related: 13 Possible Reasons Why You’re Hungry ALL The Time

While simple carbs hit our bloodstream and start this process as soon as they encounter enzymes in our saliva, fats and proteins must go through the digestive process in our stomach. Because of this, they slow the release of any sugar into our bloodstream and prevent any blood sugar rollercoasters. If you feel hungry quickly after eating, chances are your meals lack fat.

2. You’re Plagued By Brain Fog

A diet too low in fat doesn’t just leave you constantly looking for your next snack. The blood sugar roller-coaster associated with eating carbs unaccompanied by fat (or protein) also messes with your ability to focus. You feel a jittery rush when your blood sugar spikes, and a sudden struggle when it crashes and leaves your body scrambling for fuel.

Plus, if eating low-fat has also meant eating high-carb, you may end up with yeast overgrowth in your intestines, which only worsens brain fog issues.

“When we metabolize carbs, yeast organisms [that inhabit our digestive tract] produce the byproduct acetaldehyde—the same byproduct the liver makes when processing alcohol,” says Deville. If you’ve ever felt almost drunk after going to town on carbs or sugar, that’s why!

The fix: Trade refined carbs for healthy fats and proteins.

3. You’re Having Cholesterol Issues

Research shows that monounsaturated fats like olive oil and avocados promote healthy cholesterol. When we don’t eat enough healthy fats, though, we don’t provide our body with the building blocks it needs to produce cholesterol, which we need for healthy cell membrane function, says Deville. In fact, if your diet lacks healthy fats, your HDL count may even decline.

We also need cholesterol to produce bile salt, which plays a role in our body’s absorption of fat. Ultimately, that means the less fat you eat, the less able your body is to process fat—and absorb fat-soluble vitamins.

Cutting back on refined carbs and saturated fats, and eating more monounsaturated fats, can support healthy cholesterol.

4. Your Hormones Are All Over The Place

Too little healthy dietary fat and low healthy cholesterol have another significant effect on your health: They compromise your ability to produce certain hormones. “Cholesterol is the precursor for estrogen, progesterone, testosterone, and all of the hormones produced by your adrenal glands—DHEA, cortisol, and aldosterone!” Deville says.

When these hormones are thrown out-of-whack, a plethora of side effects pop up downstream. “Imbalances of these hormones can contribute to anxiety, depression, food cravings, and poor sleep, which spurs further hormone imbalances and weight gain,” says Serena Goldstein, N.D., a naturopathic doctor in New York City. All of these issues feed right back into worsening symptoms.

Related: 6 Foods That Might Be Messing With Your Hormones

Cholesterol aside, “fat cells also produce the enzyme aromatase, which turns testosterone into estrogen,” says Goldstein. When in balance, estrogen promotes the feel-good hormone serotonin. But when out of balance, estrogen can suppress the sleep hormone melatonin and inhibit thyroid function. Out-of-balance testosterone also causes problems for both men and women, since it affects muscle mass, mood, and more.

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