What is fat, and how much do you need?

For a long time, fats had a bad reputation. But now we know that they’re a key part of a healthy, balanced diet. 

Not all fats are equally healthy, though. In this article, we’ll explore the different types and what roles they play in your body.

Plus, we’ll look at why there’s no one-size-fits-all answer to the question of how much fat to eat every day.

The Academy of Nutrition and Dietetics recommends that you get 20–35% of your daily energy intake from mono- and polyunsaturated fats and less than 10% from saturated fats. 

But these figures can vary, based on your body’s unique needs.

ZOE’s PREDICT research program is the largest of its kind, with more than 50,000 participants so far. We found that even genetically identical twins can respond differently to the same types and amounts of fats.

With the ZOE at-home test, you can find out how your body responds to fats and carbs, and which bacteria you have in your gut microbiome. 

Based on your results, our personalized nutrition program guides you toward eating the best foods for your body. You’ll learn about the best types of fats for you and how much to eat each day. 

Take our free quiz to get started.

How much fat do you need?

Your ideal daily fat intake partially depends on your body and health goals. 

Over the years, manufacturers have marketed low-fat products as healthier than their regular alternatives. 

But the truth isn’t so simple — even the most recent Dietary Guidelines for Americans don’t suggest an upper limit for our total fat intake. 

They do recommend that saturated fat provides no more than 10% of your total daily energy intake. 

What are the types of fat?

Fats consist of long strings of carbon and hydrogen molecules.

The different types of fats are categorized by how these molecules link together: whether there are single or double bonds between the carbons in their structures.

These links determine whether a fat is liquid or solid at room temperature.

Saturated fats

Saturated fats — like those in lard and butter — stay solid at room temperature thanks to the single bonds between their carbon atoms.

It’s worth noting that saturated fats are not the enemy. We dedicated an episode of the ZOE Science & Nutrition podcast to explaining why they’re misunderstood. 

Much of the evidence suggests that eating a lot of saturated fat is linked to raised levels of “bad” cholesterol, which in turn is a risk factor for heart disease. But this may be an overly simplistic view. 

In fact, the effect of saturated fat might depend on the food that contains it.

For example, dairy products and processed meats are both high in saturated fats, but they’re likely to have very different effects on your health.

A 2020 review found that certain foods rich in saturated fats — like full-fat dairy, dark chocolate, and unprocessed meat — do not increase the risk of cardiovascular disease.

In fact, full-fat dairy may help reduce the risk of developing type 2 diabetes and heart disease, as well as improve bone health. 

So, ruling it out because of its saturated fat content isn’t necessarily healthy, and getting some saturated fat is important.

Unsaturated fats

Some carbon atoms in unsaturated fats have a double-bond connection.

Monounsaturated fats have only one double bond in every molecule. Polyunsaturated fats have two or more double bonds. Both are liquid at room temperature.

These types of fat occur in olive, canola, fish, and sunflower oils. They can help reduce levels of “bad” cholesterol. This is low-density lipoprotein (LDL) cholesterol, the kind that can build up in the walls of your blood vessels and contribute to your risk of heart disease.

Trans fats

Artificial trans fats are cheap and stable at all temperatures. They have similar properties to animal fats.

Research has linked these fats to higher LDL cholesterol levels and an increased risk of diabetes, cancer, depression, and heart disease.

Artificial trans fats are banned in the United States

But not all trans fats are artificial — some occur naturally in cow, sheep, and goat milks. Researchers have found that a moderate intake of these trans fats doesn’t seem to be harmful. 

What are fats for?

Fats play a variety of crucial roles in your body. For instance, they’re necessary for the absorption of fat-soluble nutrients, like vitamins A, D, E, and K. 

While your body can make most types of fat, it can’t create essential fatty acids, like omega-3 and omega-6 fatty acids — you have to get these from your diet.

Omega-3 fatty acids benefit your brain and heart health, reduce inflammation, and support wound healing.

The bottom line is that every type of fat can be useful when you eat it in moderation as part of a diverse, healthy diet.

Does it matter when you eat fats?

Timing does matter, but it’s different for everyone. 

When you eat, any fat in the meal enters your bloodstream. It’s transported throughout your body in the form of triglycerides. When these reach your cells, your body turns them into energy or puts them in storage for later. 

While sugars from your diet enter and exit your blood relatively quickly, fats stay in your bloodstream for much longer

In our own research, we’ve shown that some people take much longer to break down the fat in their blood after a meal. 

And if you eat another meal before your body has processed the fat from your last meal, it can lead to raised blood fat levels that last throughout the day. In the long term, this can increase your risk of developing heart disease.

Everyone has a personal “fat threshold.” Staying below this threshold means that your body can process most of the fats in your blood before you eat again. 

ZOE’s PREDICT1 study shows that people’s blood fat responses can be very different, even after they eat the same food.

So, the best time to eat fats depends on your body’s unique needs.


Fats are a vital part of a healthy, balanced diet. The Academy of Nutrition and Dietetics recommends that fats should contribute about 20–35% of your daily energy intake. But the right amounts of each type of fat depend on your unique body.

Rather than getting out a calculator, focus on the quality of the fats that you eat, and include healthy fats in your meals and snacks.

The key is to have an overall healthy diet based around whole foods and healthy fats, with fewer highly processed foods

Meanwhile, research into the long-term effects of different types of fat is ongoing.

Saturated fats have a reputation for being unhealthy, but in moderation, they’re an important part of a healthy diet.

Unsaturated fats — like those in vegetable oils and fish — help maintain healthy LDL cholesterol levels and a healthy heart.

Artificial trans fats increase your risk of various health conditions, and they’re banned in the U.S. Natural trans fats are different, and current research suggests that they’re not linked to a higher risk of heart disease. 

Fats stay in your bloodstream longer than sugars. So, when you eat fats and how much you eat are important considerations.

But keep in mind that the amount of time it takes your body to clear fats from your blood varies from person to person.

The ZOE at-home test can help you understand your blood fat response, your blood sugar response, and which bugs are in your gut microbiome.

From this information, we’ll provide you with nutrition advice tailored to your body, including which fats are best for you and how much of them to eat every day.

Take our free quiz to learn how ZOE could support your health.


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