Talking about saturated fat is tough, largely because it’s such a polarizing issue. Depending on what you read, saturated fat is depicted as the ugly, heart-disease-causing stepchild of the fatty acid world, or it’s shown as the prodigal son that should be hailed with impunity.
This debate has lasted for 50 years, in part because, despite the strong claims, the research on saturated fat is oddly inconclusive. As a quick example, there have been ten scientific reviews of saturated fat and heart disease in the last ten years:
- 4 found that saturated fat causes heart disease [1,2,3,4]
- 4 found that it doesn’t [5,6,7,8]
- 2 found that the data were too messy to make a conclusion one way or the other [9,10]
For the record, we fall strongly in the middle. We’re not convinced that saturated fat will kill you, nor are we convinced it’s a cure-all for all health conditions. Based on current research, it seems to be pretty neutral – a solid source of energy that, provided you’re getting it from good foods, has a comfortable place in a healthy diet. Nothing too dramatic.
We’ll explain our reasoning fully over time, and hopefully, by the end of this series of articles, you’ll be comfortable eating a nice seared steak with butter, or cooking your veggies in coconut oil.
In this article, we want to start with the essentials: how does your body actually use saturated fat?
Let’s get into it.
Brief recap: what is saturated fat?
Note: If this section piques your curiosity, you can check out this basic guide to fats for a deeper look at the many types of fat.
There are two major types of fat: saturated and unsaturated.
- Saturated fat molecules are nice straight lines, which lets them pack together tightly like sardines in a can. Packing together so well makes saturated fats solid at room temperature. They’re also the most stable, rigid fat. Think butter and coconut oil.
- Unsaturated fat molecules have kinks in them. The kinks mean they don’t pack together as neatly as saturated fats, leaving them liquid at room temperature instead of solid. Unsaturated fats are also more fluid and less stable.
Your body needs a mix of saturated and unsaturated fats to function well. You can read about unsaturated fats here. For this article, let’s dive a little deeper into what your body does with saturated fat.
How your body uses saturated fat
Your body uses saturated fat in two ways: structurally and for energy.
Because saturated fat molecules are so rigid, your body turns to them in places where stability is valuable.
Saturated fat for structure
One such place is your cell membranes. Cell membranes give shape to your cells and decide what goes in and out of them. Your cell membranes want to hit the sweet spot of flexible stability, so they combine fluid unsaturated fat and rigid saturated fat. Saturated fats make up about 50% of the average cell membrane, and the lion’s share of the fats in your brain cells are saturated .
The insides of your lungs are also coated in saturated fat. The coating is called pulmonary surfactant, and it keeps your lungs pliable enough to expand fully, yet structured enough that they don’t collapse when you exhale.
You also use saturated fat for energy
Nearly every cell in your body contains mitochondria. These little powerhouses take in broken down carbs, fats, and proteins from the food you eat and turn them into energy, in the form of ATP (adenosine triphosphate). ATP is what runs your entire body. Every one of your movements, heartbeats, breaths, thoughts, and so on is thanks to your mitochondria creating ATP.
Your mitochondria usually turn to carbs before any other fuel source, provided carbs are available . For example, if you eat a sweet potato with butter, you’ll burn through the carbs in the sweet potato first. If your body still needs more energy, your mitochondria go to work on the fat in the butter. If not, you’ll store that butter as body fat, saving it for leaner times in the future.
But in the absence of carbs, your mitochondria will happily burn fat for fuel. Say you just woke up and you’ve burned through carbs from dinner the night before and you have some coffee with heavy cream. The only thing new to your system is a bit of saturated fat.
Step 1: getting fat to your mitochondria
Fat metabolism (your body’s way of breaking down fat and using it for energy) is a fascinating process. Let’s break it down:
- Some people argue digestion actually starts in your brain. With the thought of food or delicious smells wafting through your kitchen, your brain sends signals to your salivary glands and digestive system to begin the secretion of digestive enzymes.
- Let’s go back to the cream in your coffee example. The lipase enzyme in your saliva begins the breakdown of fat into glycerol and fatty acids. But this is just the beginning! The majority of fatty acid breakdown happens in the small intestine. Your cream has a ways to go.
- From your mouth, the partially digested cream travels down your esophagus, through your stomach, and into your small intestine.
- This is where the magic happens. Bile from your liver emulsifies the fat, mixing it with water to form tiny droplets. These droplets create more surface area for pancreatic enzymes to break fat molecules down into fatty acids, the building blocks of fat.
- Fatty acids are then absorbed by cells in your gut lining and repackaged into little shuttles called chylomicrons.
- Chylomicrons carry the fat into your bloodstream. From there, they deliver it to mitochondria in parts of your body that are looking for energy. Your mitochondria then happily gobble up these little fat packets as fuel so you can do things like move around and think and read this article.
For example, if you go for a run after your coffee with cream, the chylomicrons will shuttle fatty acids to the mitochondria in your leg muscles.
Step 2: Creating fuel
Once they arrive in your mitochondria, fatty acids go through something called beta-oxidation – your mitochondria slowly chews through the fatty acid, sends the products through the Krebs Cycle (sound familiar? From high school biology, maybe?) and spits out ATP, all shiny and ready to use as energy.
Whew. That’s how your body actually breaks down fats for energy.
What if you don’t eat much saturated fat?
Your body is resourceful. If you don’t feed it saturated fat, it goes rogue and starts making its own saturated fat from carbohydrates.
On a standard Western diet, you make about 2 grams of saturated fat every day . If you eat very little saturated fat, your body compensates by making more of it – up to around 10 grams a day for someone on a very low-fat diet .
Basically, as long as you’re not starving yourself, your body will find a way to get its baseline needs for saturated fat. Beyond that, saturated fat becomes a source of energy.
Are there benefits to using fat for energy?
It depends on the rest of your diet.
Your mitochondria generally turn to carbs for energy when carbs are available. But you don’t store carbs in your system for long. Within 24 hours of not eating carbs, your reserves run out, which is when many people start craving bread, sugar, and so on.
But if you power through the cravings and continue to limit carbs for a few days, your mitochondria will switch over to burning fat as their main fuel source. Many people report more stable energy and a less urgent sensation of hunger on low-carb diets – likely because their mitochondria are used to burning fat, and using up body fat for fuel feels more comfortable than it does when your mitochondria are used to carbs.
In short, some people seem to do better with a low-carb diet, where they’re running mostly on fat. Others seem to do better on a high-carb diet. Try both and see which you prefer.
While you’re playing around with your fat intake, though…
Choose good sources of saturated fat
This is where Americans get their saturated fat (data taken from this giant national survey):
Crunching the numbers, you’ll see that:
- 37.5% of saturated fat intake comes from pizza, grain-based desserts (cookies, cakes, and the like), dairy desserts (ice cream), processed meats, candy, chips, fries, pasta, and burritos/tortillas.
- Another 24.5% comes from the nebulous “All other food categories.”
- Only 24.2% of Americans’ saturated fat comes from whole foods like beef, eggs, full-fat dairy, butter, and nuts.
This is where it’s important to contextualize saturated fat intake. While they may have similar saturated fat content, whole eggs and beef are very different from cupcakes and potato chips. The first two are nutrient-dense sources of protein, precious fats, antioxidants, and so on. The latter two include sugar, damaged/inflammatory fats, food additives/chemicals/colors, and very little nutrient value.
Nutrition is a bigger picture than any single nutrient. If you’re eating quality food – plenty of veggies, adequate protein, minimal sugar, and so on – we’d say saturated fat has its place in your diet.
So whether you’re getting 3% or 30% of your calories from saturated fat, choose good sources. Some excellent options are:
- Eggs (Vital Farms has good pasture-raised eggs, and you can find them in most stores)
- Coconut oil
- Beef or lamb (US Wellness Meats has superb grass-fed meat)
- Butter (Kerrygold is a great brand)
- Full fat cheese, yogurt, cream, and other dairy
- Bacon and other cured meats
- Tallow or lard
Ideally, you’ll get all the animal products above from grass-fed or pasture-raised animals so you can enjoy an extra helping of precious omega-3s as well .
Any questions or comments? We’ll be looking for them below.