Fats 2 | APRIL ‘25

Written By Vincent Panza

The Skinny on Fats: A BIOCHEMISTRY LESSON

Today, we’re breaking down the three main types of dietary fat: saturated, monounsaturated, and polyunsaturated fats. We’ll explore how they differ structurally, what that means for your health, and why polyunsaturated fats tend to oxidize more easily (hint: chemistry matters!).

First, a Quick Fat Primer

Fats are made up of fatty acids, which are long chains of carbon atoms. The type of fat depends on how the carbon atoms are bonded:

  • Saturated fats have no double bonds between carbon atoms

  • Monounsaturated fats have one double bond

  • Polyunsaturated fats have two or more double bonds

These differences might sound like high school chemistry, but they make a huge difference in how these fats behave in your body and in food.

1. Saturated Fats: Solid but Controversial

Saturated fats are “solid at room temperature” fats. Think butter, coconut oil, lard, and the marbling you see in your steak. Chemically, their lack of double bonds makes them stable, meaning they don’t oxidize easily and can withstand high-heat cooking.

Where you’ll find them:

  • Red meat (beef, pork, lamb)

  • Full-fat dairy (cheese, cream, whole milk)

  • Coconut oil and palm oil

  • Butter

The skinny:

The Academy of Nutrition and Dietetics and the American Heart Association still advise limiting saturated fat to less than 10% of daily calories, recommending a shift toward unsaturated fats when possible. They’re not an evil macro, but moderation is wise — especially if you're already at risk for heart disease.

2. Monounsaturated Fats: The Mediterranean MVP

Monounsaturated fats are often considered the healthiest fat on the menu. Chemically, they contain one double bond, which gives them a little more flexibility than saturated fats but keeps them fairly stable.

Where you’ll find them:

  • Olive oil (extra virgin or regular)

  • Avocados

  • Almonds, peanuts, cashews

  • Canola oil

  • Peanut butter

The skinny:

Monounsaturated fats are the backbone of the Mediterranean diet, one of the most researched and praised dietary patterns in the world. They lower LDL ("bad") cholesterol, they maintain or raise HDL ("good") cholesterol, they support insulin sensitivity, and they reduce biomarkers associated with inflammation. AND  highlights these fats as part of a healthy diet pattern, and multiple clinical trials support their protective role in heart health and metabolic function.

3. Polyunsaturated Fats: Essential but Delicate

Now for the most complex (and arguably most important) fat group: polyunsaturated fats. These fats have two or more double bonds, making their chemical structure more “open.” That flexibility gives them unique health benefits — but also makes them more vulnerable to oxidation.

Where you’ll find them:

  • Fatty fish (salmon, sardines, mackerel)

  • Walnuts

  • Flaxseeds and chia seeds

  • Sunflower, safflower, soybean oils

  • Omega-3 enriched eggs

The skinny:

Polyunsaturated fats include two essential fatty acids: omega-3 and omega-6. Your body can’t make these on its own, so you have to get them from food.

  • Omega-3s (ALA, EPA, DHA) are anti-inflammatory, support brain health, and lower the risk of heart disease. Found in fish, flaxseeds, and walnuts.

  • Omega-6s (like linoleic acid) also play a role in immune health and cell structure but can be pro-inflammatory in excess (especially when out of balance with omega-3s).

The consensus in nutrition research is clear: most people need more omega-3s and fewer omega-6s. Modern diets tend to overload on omega-6s due to processed oils and fall short on omega-3s.

FUN FACT: Why Polyunsaturated Fats Oxidize More Easily

Their multiple double bonds make them chemically unstable, especially when exposed to heat, light, or oxygen. The kinked shape of their molecules keep them from tightly packing, allowing environmental stresses to break them apart. This is why they’re found in cold water fish — this type of fat can keep them warm in the cold waters without easily stiffening, allowing fish to stay agile enough to wiggle through the ocean.

When these fats do break down, called lipid peroxidation, it can lead to the formation of harmful compounds (like aldehydes) that may promote inflammation or cellular damage if consumed in excess over time. For this reason, polyunsaturated fats are better stored in dark bottles and cool places and are best used in cold applications (salad dressings) or low-heat cooking. That doesn’t mean they’re bad for you — far from it. Just be thoughtful in how you use them.

How to Use This Info in the Real World

To keep it simple, approach your fat intake as follows:

  • Monounsaturated fats should be a go-to: Think olive oil, avocado, nuts

  • Polyunsaturated fats, especially omega-3s, are essential for health: Prioritize fatty fish, flax, and walnuts

  • Saturated fats can have a place in a balanced diet but should be limited

  • Avoid trans fats altogether. These are artificially produced through hydrogenation and are linked with increased heart disease risk. Thankfully, most have been phased out of the food supply.

Cook with olive oil, snack on nuts, sprinkle chia seeds on your oatmeal, and eat fatty fish a couple of times a week. Limit processed foods made with refined oils and keep an eye on high-saturated-fat animal products.

And remember: fat is flavor. Including healthy fats in your meals not only supports your body — it makes your food more satisfying and keeps you fuller longer. So, don’t fear fat. Embrace it thoughtfully and always aim for balance 

Sources:

Vincent Panza
Previous

Proteins 1 | MAY ‘25

Next

Fats 1 | APRIL ‘25