Fats, Function, and the Foods That Carry Them

Michelle Donath
Nov 4, 2024
5 min read

Updated: 6 days ago

Understanding Omegas, Saturated vs Unsaturated, and What Your Body Actually Needs

Let’s start here: Your body doesn’t just use fat for energy.

It uses fat to build membranes. Make hormones. Feed your brain. Calm your nervous system. Absorb vitamins. Fat isn’t just fuel, it’s structure. It’s information. It’s functional.

Fat has been praised, vilified, brought back, and rebranded so many times it’s no wonder most of us get confused about what fats actually in, or what the body’s trying to do with it.

So let’s clear it up.

This isn’t about low-fat or high-fat. It’s about what kind of fat you eat. And how that fat behaves in your body.

The Structure Matters

Fat comes in different forms depending on the shape of its bonds.

You’ve heard the terms: saturated, monounsaturated, polyunsaturated. They’re not just labels, they tell you what that fat can do inside your cells.

Saturated Fats

No double bonds (fully saturated with hydrogen)
Solid at room temp
Stable and heat-resistant

Used for: structural support, hormone building, long-term energy.

Found in: butter, ghee, coconut oil, animal fats.

Not the villain it’s made out to be, but not a free-for-all either. Balance matters. Source matters more.

Monounsaturated Fats (MUFAs)

One double bond
Semi-liquid at room temp
Protective for heart + cell membranes

Used for: flexible membrane integrity, blood sugar balance, anti-inflammatory support.

Found in: olive oil, avocado, almonds, macadamias.

This is the fat your body often loves. Smooth, stable, and friendly to your cardiovascular system.

Polyunsaturated Fats (PUFAs)

Two or more double bonds
More fragile, prone to oxidation
Includes omega-3 and omega-6

Used for: brain, inflammation signalling, immune modulation.

Found in: fish, flax, chia, walnuts, sunflower oil, soybean oil.

Then There's The Omega Family

You’ve probably heard the terms: omega-3, omega-6, omega-9.

But they’re not interchangeable. These aren’t just labels on your chia packet, they’re structurally and functionally different. Each one plays a unique role in your biology, with different end products, pathways, and effects.

And your body doesn’t treat them equally.

Omega-3s (like EPA and DHA) are anti-inflammatory, brain-stabilising, hormone-supporting, and mitochondrial-loving. They’re essential, meaning your body can’t make them. You have to get them from food or supplements.

Omega-6s get a bad rap, but they’re also essential. They help with skin integrity, immune response, and cell signalling. The issue isn’t omega-6 itself, it’s that most people are swimming in it, without enough omega-3 to balance the scale. It’s the ratio, not the fat, that matters.

Omega-9s (like oleic acid in olive oil) aren’t essential, you can make them, but they still offer real benefit. Think cardiovascular support, blood sugar balance, and quiet anti-inflammatory action.

Each of these fats plugs into different biochemical pathways. They’re the precursors to hormones and inflammation signals.

You might’ve noticed that olive oil, almonds and avocado appear in both the monounsaturated and omega-9.

That’s not a mistake, it’s biochemistry.

Omega-9s (like oleic acid) are a type of monounsaturated fat. The "mono" means they have one double bond in their structure. The "9" tells us where that bond sits on the 9th carbon.

So when we say olive oil is rich in omega-9s, we’re also saying it’s rich in monounsaturated fat. It’s the same fat, described two different ways: by its structure, and by its function.

That’s why olive oil, avocado, and almonds wear two hats here. They offer metabolic calm and structural support, making them some of the most versatile, protective fats in your kitchen.

When it comes to mega-3s and omega-6s, they compete for enzymes and influence how your body responds to stress, repairs damage, and regulates mood.

That’s why understanding the omega family isn’t just about what to eat, it’s about how food shifts the way your body behaves.

We’ll dig deeper into this in The Great Omega Debate, where 3s, 6s, and 9s go head-to-head, and the myth of omega-6 being the villain gets unpacked.

So now that we’ve looked at the types, let’s make it real.

Here’s a breakdown of which fats come from where, and what they actually do once inside your body.

Fat Type → Food → Function Matrix

Fat Type	Whole Food Sources	What It Does
Saturated Fat	Ghee, butter, coconut, animal fat	Builds cell membranes, supports hormone production, stable for high-heat cooking
Monounsaturated Fat (MUFA)	Olive oil, avocado, almonds, macadamias	Supports heart health, balances blood sugar, stabilises cell membranes
Omega-3 (PUFA)	Sardines, salmon, anchovies, algae oil, flax, chia, walnuts	Anti-inflammatory signalling, brain + eye development, mood and mitochondrial support
Omega-6 (PUFA)	Sunflower seeds, sesame seeds, tahini, egg yolk	Immune function, skin integrity, inflammatory response (needs omega-3 balance)
Omega-9 (MUFA)	Olive oil, hazelnuts, avocado, almonds	Non-essential but beneficial: supports insulin sensitivity, reduces inflammation
ALA (plant-based omega-3)	Flaxseed (fresh ground), chia, hemp seeds, walnuts	Needs to convert to EPA/DHA, conversion limited (especially with FADS gene variants)

Your body doesn’t need every oil on the shelf. It needs fats that do something. That support real pathways. Start with whole food sources, cook with confidence, and let your fats work for you.

How Your Genes Weigh In

Some people are genetically better at converting ALA (plant-based omega-3) into EPA/DHA. Others are not.

The FADS1 and FADS2 genes influence this conversion step. If you have slow variants, you may need preformed EPA/DHA from fish or algae oil.

Genes like APOE also influence how your body transports fats, including cholesterol and DHA. So what works for one person might not land well for another.

Food is personal. And fat is part of that story

Why Fats are Also Lipids

You’ll hear me use the word “fat,” but you might also see the term lipid, especially in science-speak.

Here’s the difference:

Fat usually refers to the type we eat (and sometimes store).

Lipid is the broader biological category, it includes fats, oils, cholesterol, and the structural components of every single cell membrane you’ve got.

The Bottom Line

You don’t need to memorise lipid chemistry to build a functional food plate. But you do want to be intentional with the fats you do eat, because there’s only so much fat your body actually needs each day.

So make it count.

Choose fats with the most robust evidence for health and stability
Use olive oil EVOO confidently for cooking and dressing, its natural antioxidants help protect it (and your food) during heat
Include saturated fats from whole food sources like ghee or coconut, especially in cooking
Focus on omega-3s that deliver, like algae oil or small oily fish
Let seeds and trendy oils stay in the background, get those nutrients from their whole, crunchy sources instead