Dietary Fats: Which Are Healthy, Which Are Not?

Learn to avoid the unhealthy fats while enjoying the healthier ones.

It’s no secret that fats have suffered from a pretty bad reputation. But the truth is, we need fat to function normally. Hundreds of studies have shown that “good fats” can reduce cardiovascular disease, protect you from getting cancer, and even reduce your risk for diabetes, among many other health benefits. Omega-3 fatty acids, a specific type of healthy fat, are consumed in only limited quantities in the average American diet — despite the fact that they are considered one of the most beneficial of all essential nutrients.

So, how did we get so off course when it comes to fat? What’s the difference between saturated, unsaturated, and trans fats — and what do those words mean anyway? Here we provide a simple, to-the-point overview of dietary fats and their health benefits so that you can feel confident including fats as part of a healthy diet.

What are fats? Deciphering fat jargon

Fats began to be avoided in the 1960s when low-fat diets were all the rage — not just for heart health, but for health in general. However, the pendulum swung too far: calorie-dense fats were replaced with refined carbohydrates, and even healthy fats were avoided — contributing to the explosion of chronic conditions that plague a majority of Americans today. 

Before we discuss the health benefits of fats, let’s first define some of the numerous terms you’ve probably heard before:

Triglycerides are what we know as “fats”: Triglycerides are composed of one glycerol (a simple compound composed of carbon, hydrogen, and oxygen) and three fatty acids (chains of carbons and hydrogens). The type of fatty acid makes a fat “good” or “bad.”

The “bad fats”:

Saturated fats have a rigid, straight structure that makes them easily stackable. Because of this, they are solid at room temperature. These are “bad” fats.

Trans fats are unsaturated fats that have been modified by food chemists so that their kink faces a different direction. Because of this, they are more easily stackable; and, like saturated fats, they become solid at room temperature. Because they are unnatural fats, they should be avoided. 

The “good fats”:

Unsaturated fats have a kink in their structure that makes them “bent.” Because they are bent, they cannot stack on top of each other very well and remain liquid at room temperature. These are “good,” or healthy, fats.

  • PUFA is a polyunsaturated fatty acid, or an unsaturated fatty acid that has more than one kink in the chain.
  • Omega fatty acids, particularly omega-3 and omega-6, are good fats because they reduce the risk of atherosclerosis, obesity, and other diseases. 
  • ALA, EPA, and DHA are food-derived omega-3 unsaturated fatty acids commonly found in supplements and with several health benefits (see more below).

What are omega fatty acids?

Omega fatty acids are unsaturated fatty acids. Their name is derived from the number of carbons between the kink and the last carbon in the chain. The two essential omega fatty acids are omega-3 and omega-6. They are essential because we can only get them from the food we eat. Another type of omega fatty acid, omega-9, can also be obtained from food, but it’s not considered an essential nutrient because our bodies can make it.

You’ve probably heard that omega-3 fatty acids are good and omega-6 fatty acids are bad. This is a common myth; both have health benefits. The problem is that in modern, Western diets, twenty times more omega-6 fatty acids are consumed than omega-3s. When the balance between the two is so disrupted, inflammation and a greater risk of atherosclerosis, obesity and diabetes occurs. To support health, you should try to eat an equal balance of both types of fatty acids — or, at most, twice the amount of omega-6 as omega 3. Common food sources of both are listed below:

  • Omega-3 food sources: fatty fish (think salmon or mackerel), nuts, seeds, oils, and some vegetables and herbs (Brussel’s sprouts, basil)
  • Omega-6 food sources: meat (think beef, lamb, chicken), seafood, and vegetables like spinach, kale, and broccoli

You can also obtain omega-3 fatty acids from supplements like fish oil or algae. These supplements contain the most common omega-3 fatty acids: EPA (anti-inflammatory) and DHA (boosts brain health). Complete supplements will contain both; if yours only contains one, toss it and find one that has both EPA and DHA. Additionally, other supplements may contain ALA, a closely related omega-3 fatty acid important for human growth and development and commonly used to support cardiovascular health.

What are the health benefits of fats?

1. They are good for your heart

Several studies have connected omega-3 fatty acid consumption and beneficial effects for the heart. Omega-3 fatty acids can:

  • Prevent cardiovascular disease and myocardial infarction (i.e., heart attack)
  • Reduce cardiovascular death and sudden cardiac death in people who recently suffered from a heart attack

Additionally, eating too little omega-3 fatty acids can increase hypertension and blood clotting, and, therefore, the risk for heart attack and stroke. 

2. They are good for your brain

Several studies have also shown beneficial effects on the brain from omega-3 fatty acid consumption. Omega-3 fatty acids can:

  • Support optimal brain function and eyesight
  • Help treat and prevent mental illness
  • Improve concentration, learning, and IQ
  • Promote brain tissue growth and help repair tissue damage 

3. Other health benefits

In addition to the well-studied heart and brain related benefits of omega-3 fatty acid consumption, they’ve been shown to have several other health benefits:

  • Cancer prevention
  • Prevention of psoriasis
  • Prevention of bronchial asthma
  • Decreased inflammation and joint pain
  • Increased insulin sensitivity
  • Increased energy and stamina
  • Improved wound healing
  • Weight management
  • Reducing autoimmune disease symptoms

Fats and type 2 diabetes

Although several studies have suggested that both omega-3 and omega-6 fatty acids could have a beneficial or protective effect in type 2 diabetes (T2D), several other studies have shown the exact opposite. So, the jury is still out. Nevertheless, a large body of research studies, including large-scale analyses reviewing hundreds of existing studies, all seem to come to these key conclusions:

  • A majority of type 2 diabetes patients suffer from dyslipidemia — elevated triglycerides, low high-density lipoprotein cholesterol (HDL-C; “good cholesterol”), and high LDL (“bad cholesterol”).
  • Dyslipidemia in type 2 diabetes is a major link between diabetes and cardiovascular disease.
  • Lipid changes might not just be a characteristic of altered glucose metabolism; they might actually help cause it. This is because elevated triglycerides lead to increased free fatty acids, which can induce insulin resistance and β-cell dysfunction.
  • Consumption of omega-3s, omega-6s, and PUFAs has little to no effect on type 2 diabetes prevention or treatment, and too much omega-3 can actually be detrimental.
  • A diet containing a typical mix of good and bad fats appears to have no effect on type 2 diabetes development, but additional studies are needed to determine if higher consumption of specific fats might correlate with type 2 diabetes prevention.

Key takeaways

Contrary to the decades-old narrative, fats aren’t the bad guy — but not all fats are created equal. Saturated fats and trans fats should be avoided, but our bodies need healthy amounts of unsaturated fats, like omega-3 fatty acids, to function normally. Making sure that we eat equal amounts of omega-3 and omega-6 fatty acids can help promote a healthy heart, healthy brain and eyes, healthy weight, improved energy, and so much more. And, although many studies suggest that unsaturated fatty acids could help people with type 2 diabetes, more research is needed before we can say for sure. If you have type 2 diabetes, the best thing to do is work with your doctor to find the best combination of diet, exercise, and medication to control your condition.

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