Fat has been the dietary villain for decades. Starting in the 1940s, studies found a connection between high-fat diets and elevated cholesterol levels, which can lead to coronary blockages and heart disease. By the ’60s, a low-fat diet was recommended by physicians, and the government, health media, and general public started to find other things to add to their food, like sugar. Then we realized all that added sugar was terrible for our waistlines and risk of type 2 diabetes, and by the '80s we were back on the low-fat train.

Throughout the decades, Americans have gotten fatter and our obesity rates have soared. Heart disease is the number one killer in the US and nearly half of Americans are diagnosed with heart disease while the other half probably has it but we don't know it yet. So here's the question: How much fat is too much fat? And which fats are healthier to allow into our diet?

You can have too much fat, even healthy fat

Lately, there's been a lot of research to confirm that there are unhealthy fats such as from meat and dairy, and healthy fats such as from nuts, seeds, and plant-based foods, which if eaten in moderation can be considered an important part of a healthy diet. The problem is that even healthy fats are calorie-dense – one tablespoon of olive oil has 119 calories, for instance – so if weight control is an issue, there is that.

For anyone who has been told to limit fat and go on a whole-food, plant-based diet, either to treat or reverse heart disease, fatty liver, obesity, diabetes, or other condition, any amount of fat can be considered something to limit. That’s why we are discussing healthy fats, including what they are, how much you should allow into your diet, and what foods provide them.

What are healthy fats vs. unhealthy fats?

There are four different types of dietary fats, according to the American Heart Association:

  • Saturated fats
  • Trans Fats
  • Monounsaturated fats
  • Polyunsaturated fats

Each of these has different chemical structures and physical properties. Saturated and trans fats are solid at room temperature (like butter) while the polyunsaturated and monounsaturated fats are liquid (like olive oil).

Saturated and trans fats are considered the worst type of fat to eat because they raise LDL or  “bad” cholesterol, which leads to the formation of plaque, clogged arteries, high blood pressure, and eventually heart disease in the form of risk of heart attack or stroke.

Examples of foods that contain saturated and trans fats are:

  • Animal products: Red meat, butter, cheese, and cream
  • Tropical oils: Coconut oil, palm oil, and palm kernel oil
  • Margarine: Solid at room temperature, vegetable shortening
  • Fried foods such as fried chicken, french fries and calamari
  • Baked goods such as cookies, muffins, cupcakes, banana loaves, etc.

Good fats benefit your brain health

On the other hand, there are good fats, which are the mono and polyunsaturated fats that generally are liquid at room temperature, come from plant-based sources such as olive oil, and act completely differently in the body, and instead of blocking up the works, you can think of these as "greasing the wheels." You still don't want to much, but they are not to kill you.

These fats can help improve cholesterol levels (lowering LDL and raising HDL) as well as provide important nutrients like vitamin E, according to the American Heart Association. A type of polyunsaturated fats – omega-3 and omega-6 fatty acids –  are also very beneficial for our overall cell function, brain health, and digestive health. There are many different omega-3 forms, but the most commonly studied include ALA, EPA, and DHA.

The benefits of these fats, according to the National Institute of Health:

  • Decreased risk of cardiovascular disease (CVD) and CVD risk factors
  • Assist with infant health, neurodevelopment
  • May prevent certain cancers including breast, colorectal, and prostate
  • Reduced risk of cognitive decline, Alzheimer’s disease, and dementia
  • Lower risk of age-related macular degeneration (severe vision loss among older adults)
  • Prevent dry eye disease
  • Reduce symptoms of rheumatoid arthritis

Our body can’t make omega-3 fats, so it’s important to get them from our diet (see below for food sources of all these healthy fats).

Omega-6 fats are usually more prominent in the Western diet, which includes high intakes of processed foods and red meat (it can also be found in foods such as seeds and vegetable oils).

The ratio of omega-6 to omega-3 fatty acids in the Standard American Diet is about 15:1, according to a 2020 study, when it should be more like 1:1 up to 4:1.

Omega-6 fats play an important role in the function of our cells, but eating too much may actually change the way our cells react and can cause problems. That’s why the ratio of omega-6 to omega-3 is so important to uphold.

How much healthy fat should I be eating?

When it comes to saturated fat, you want to limit it as much as possible. The 2020-2025 Dietary Guidelines for Americans recommends saturated fat to be less than 10 percent of your total calories per day. Trans fat should be avoided completely.

What is the right amount of healthy fat?

Even though healthy fats are beneficial, they shouldn’t be eaten with zero limitations. The Academy of Nutrition and Dietetics recommends eating around 20 percent to 35 percent of your total daily calories in the form of healthy mono and polyunsaturated fats.

For example, if you eat a 2,000 calorie diet, you will want to consume around 44 to 77 fat grams per day. Omega-3’s (more specifically the ALA omega-3) have an adequate intake of 1.6 grams per day for adult males and 1.1 grams for adult women. There is not a set intake requirement for EPA or DHA, since ALA has the ability to be converted into them.

If you eat a diet that is about 1,800 to 2,000 calories a day (depending on your age, size, weight, activity level, and goals) then your total fat intake should not exceed about 300 to 400 calories. One tablespoon of olive oil has 119 calories. An avocado has 234 calories, and while research shows there are heart benefits and even weight-loss associated among people who regularly eat avocado, you still want to watch your total fat intake. So you get to choose, which healthy fats to mix and match, but they add up fast.

Fats are also the highest calorie macronutrient, containing 9 calories per gram compared to protein and carbohydrates that contain 4 calories per gram. Therefore, eating too much fat could lead to weight gain.

List of healthy fats

Now that we know how much to eat, where do we get these healthy fats from? While many foods contain a combination of fats, they sometimes tend to have a higher amount of one versus the other. Check out this list of healthy fat foods.

Monounsaturated Fats

If you’re looking to amp up your monounsaturated fat intake, you’ll want to add the following foods to your next grocery list according to MedlinePlus:

  • Nuts
  • Avocado
  • Canola oil
  • Safflower oil
  • Sunflower oil
  • Peanut oil and butter
  • Sesame oil

Polyunsaturated Fats

MedlinePlus lists high polyunsaturated fat foods as:

  • Walnuts
  • Sunflower seeds
  • Flax seeds or flax oil
  • Chia seeds
  • Fish, including salmon, mackerel, herring, albacore tuna, and trout
  • Corn oil
  • Soybean oil
  • Green leafy vegetables (sources of ALA)

Bottom Line: Healthy fats are an important piece of our diet, they can support brain health, reduce the risk of CVD, and improve cholesterol levels.

Although they are beneficial, too much of a good thing can become a problem, especially if you already are experiencing heart disease, artery blockage, or fatty liver disease. Because of the calorie density of these foods, eating high amounts of so-called healthy fats in nuts, olive oil or seeds may lead to weight gain, which could then offset the benefits of healthy fats.