How Dietary Fat Can Affect Your Cardiometabolic Health

For decades, fat was painted as the dietary villain implicated in everything from heart disease to diabetes to weight gain. But new evidence suggests that when it comes to cardiometabolic health, not all fats are created equal. This means that the fats you choose to include in your diet can either raise or lower your risk of cardiometabolic problems.  

Did you know? Cardiometabolic disease syndrome is on the rise, affecting approximately 25% of all adults globally. It has become so prevalent, it’s now recognized by the World Health Organization and the American Society of Endocrinology. (35) In North America, cardiovascular disease is the number one cause of death. (9)

Types of cardiometabolic diseases

Before discussing the role fat plays in cardiometabolic health, let’s take a closer look at cardiometabolic disease itself. If you’ve never heard of cardiometabolic disease syndrome, you’re not alone. It’s a fairly new term. Once known as syndrome X or metabolic syndrome, it encompasses both cardiovascular and metabolic diseases. (14) But despite the name change, the risk factors that cause cardiometabolic disease syndrome—chronically high blood sugar, high blood pressure, unhealthy cholesterol levels, high triglyceride levels, and excessive belly fat—are the same. (32) Having just one of these risk factors can be a concern, but when they are combined, they set the stage for some severe health problems, including: 

• Atrial fibrillation (4)
• Coronary artery disease (4)
• Diabetes (25)
• Heart attack (4)
• Heart failure (38)
• Insulin resistance (13)
• Non-alcoholic fatty liver disease (5)
• Stroke (4)

What is dietary fat and why do we need it?

Despite reports linking dietary fat to these conditions, fat is an essential macronutrient you need for good health. Fat provides your body with the energy it needs to function optimally. (6) It also cushions your internal organs, supports healthy cell growth, produces important hormones, and is critical for the absorption of fat-soluble nutrients like vitamins A, D, E, and K. (1) Even though we need a certain amount of dietary fat for good health, two types of fat may be more harmful than helpful, especially for cardiometabolic health. 

Trans fats

There are two types of trans fats—natural trans-fatty acids found in meat and dairy and artificial trans fats, listed on nutrition labels as “partially hydrogenated fats.” These artificial trans fats are considered the most harmful of all fats since they have been shown to significantly raise low-density lipoprotein (LDL), a type of cholesterol linked to cardiovascular disease. (17) They also increase the risk of insulin resistance and type 2 diabetes. (27) 

Did you know? In 2015, the U.S. Food and Drug Administration (FDA) ruled that food manufacturers must remove artificial trans fats from their products by June 18, 2018; however, some manufacturers were granted an extension into 2021. (10) 

Here are some of the most common foods that may be harboring trans fats:

• Coffee creamer
• Crackers, cookies, cakes, frozen pies, and other baked goods
• Fast food
• Frozen pizza
• Microwave popcorn
• Ready-to-use frostings
• Refrigerated loaves of bread and biscuits
• Snack foods
• Vegetable shortenings and some stick margarines (2)

Did you know? Trans fat is found in many processed foods. But buyer beware! Even foods that claim to contain 0 g of trans fats may still have up to half a gram of trans fats per serving. Be sure to double-check the ingredient lists found on packaged foods to see if they list partially hydrogenated oil. (11)

Saturated fat 

Saturated fats are fat molecules that don’t have double bonds between their carbon molecules because they are saturated with hydrogen molecules. This makes these molecular bonds stronger, and therefore saturated fats are typically solid at room temperature. (3)

For many years, saturated fat was considered harmful because it was believed to raise low-density lipoprotein (LDL) levels and increase the risk of cardiovascular disease. (12) Interestingly, a 2020 meta-analysis demonstrated that reducing saturated fat resulted in little to no reduction in the risk of cardiovascular death, cancer, all-cause mortality, or type 2 diabetes. The same meta-analysis also noted that reducing saturated fat had little to no effect on high-density lipoprotein (HDL) cholesterol or triglyceride levels; however, the review did note minor reductions in weight, serum total cholesterol, LDL cholesterol, and body mass index (BMI). (15) While the jury may still be out on the impact of saturated fat on cardiometabolic health, the American Heart Association recommends consuming just 5 to 6% of your daily calories from saturated fat. (31)

You can find saturated fat in:

• Beef
• Butter
• Cream
• Lamb 
• Lard
• Milk
• Pork
• Poultry with skin
• Tallow (3)

Dietary fat and cardiovascular disease

Aside from raising LDL levels, how do trans and saturated fats affect your cardiovascular system? Dutch researchers recently reported that trans fats trigger inflammation, which can damage the inside walls of your arteries. They also note that these industrial fats can promote fat storage in the liver, which can lead to fatty liver disease, and change the way the liver synthesizes cholesterol. (29)

One study involving more than 57,000 women published in PLoS found that those with the highest level of a biomarker indicating a diet rich in trans fats had a 57% higher risk of a heart attack. (18) 

Other findings suggest that while saturated fat may not be as detrimental to health as experts once thought, moderation may still be advised. A study in the Annals of Nutrition and Metabolism reported that swapping saturated fats for polyunsaturated fats lowered the risk of a heart attack or stroke by as much as 17%. (26) That’s because plant-based polyunsaturated fats like flaxseed or sunflower seed oil may reduce inflammation and improve blood flow in arteries. (8)

Dietary fat and insulin resistance

Although most of the research on dietary fat has focused primarily on heart health, a diet high in unhealthy fats can also cause insulin resistance. Some research suggests that trans fat can trigger various types of stress in the body that can damage your cells and keep them from responding properly to insulin. (33) In contrast, a 2020 meta-analysis concluded that saturated fat intake has little to no effect on diabetes risk. (15)

Insulin resistance can contribute to the development of both type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). As the body becomes less sensitive to insulin, it creates inflammation. Inflammation can then lead to more insulin resistance and, again, more inflammation. This vicious cycle causes blood sugar levels to increase over time, eventually resulting in diabetes. (7) 

Insulin resistance can also cause excess fat to accumulate in your liver. According to a recent study, insulin resistance can also speed up how quickly NAFLD develops into a more serious liver condition called non-alcoholic steatohepatitis (NASH). (21) A new study in the journal Metabolism suggests that a diet high in trans fats can also accelerate the development of NAFLD. (19)

How to pick the right fats for cardiometabolic health

So what fats should you eat? The healthiest types of fat are monounsaturated and polyunsaturated fats. Studies show these can enhance your cardiometabolic health.

Monounsaturated fats

Some studies show that a diet high in monounsaturated fats can improve insulin sensitivity and cardiovascular risk factors. When Swedish researchers swapped saturated fat for monounsaturated fat in the diets of 162 people, they found that insulin sensitivity improved nearly 9% and LDL levels were lower after just three months. (37) Other studies show that trading in saturated fat for monounsaturated fat reduces both LDL and total cholesterol, while raising heart-healthy HDL. (39) It also lowers blood sugar and blood pressure. (30) 

Good sources of monounsaturated fat include:

• Almonds
• Avocados 
• Cashews 
• Olive oil 
• Pistachios
• Pork 
• Pumpkin seeds
• Sunflower seeds (22)

Polyunsaturated fats

There are two types of polyunsaturated fats: omega 3 fatty acids and omega-6 fatty acids. Omega-3 and omega-6 polyunsaturated fatty acids play important roles in inflammation. In general, omega-3s are anti-inflammatory, while omega-6s are pro-inflammatory. (16) Eating too many omega-6s and too few omega-3s is thought to promote inflammation and contribute to cardiometabolic disease. (36) That’s why it’s important to balance these two polyunsaturated fats. 

According to a study conducted by The Center for Genetics, Nutrition and Health, a nonprofit health organization in Washington, DC, the optimal ratio of omega 6s to omega 3s is one to one. However, most people eating a Western diet today consume a ratio of about 16 to one. (34) While eating a diet rich in both omega-3 and omega-6 fatty acids can benefit cardiometabolic health, it’s important not to over consume omega-6s. (20) Here’s where to find healthy sources of both these polyunsaturated fats.

Omega-3 fatty acids can be found in:

• Anchovies
• Chia seeds
• Cod liver oil
• Flax seeds
• Herring
• Mackerel
• Oysters
• Salmon
• Sardines
• Soybeans
• Walnuts (24)

Omega-6 fatty acids can be found in:

• Eggs
• Grapeseed oil
• Hemp seeds
• Peanut butter
• Pine nuts
• Safflower oil
• Sunflower seeds (23)

The bottom line

Replacing trans fats and saturated fats with healthier monounsaturated and polyunsaturated fats can help support cardiometabolic health. Start by trading ultra-processed and fast foods for less processed options rich in these beneficial fats. Bonus? By choosing whole, minimally processed food, you’ll automatically bring your omega-3 and omega-6 ratio into a more cardiometabolic-friendly zone.