You might eat lots of fat.
You might not eat much fat at all.
Regardless, you likely have questions about it.
In this post, we’ll cover the basics about dietary fats and what kinds you may or may not want to eat (and how much).
What are fats?
Fats, in the context of what we eat and what we have on our bodies, belong to a class of molecules called lipids, and comprise three fatty acids attached to a glycerol backbone (1).
What role do fats play in the body?
We use fats for energy storage, hormone production, cell membrane synthesis, brain and nervous system structure and function, absorption of fat-soluble nutrients like vitamins A, D, E, and K and phytonutrients, and as a source of essential omega-3 and omega-6 polyunsaturated fatty acids (2).
Not all fats are created equal when it comes to their effects on our health.
What are healthy fats?
Omega-3 fatty acids – particularly those from fatty fish – are associated with reduced risk of cardiovascular disease, neurodegenerative disease, Alzheimer’s, schizophrenia, and depression (6, 7, 8, 9).
What are unhealthy fats?
Artificial trans fats – found in hydrogenated vegetable oils used in baked goods, margarine, and other oils and spreads – have been linked to systemic inflammation, cardiovascular disease, insulin resistance, Alzheimer’s, and cognitive decline (10, 11, 12).
That said, natural trans fats from ruminants like sheep and cows don’t appear to promote the same adverse health outcomes as artificial trans fats (13).
Some natural ruminant trans fats, like conjugated linoleic acid (CLA), might even be quite good for our health (14).
For other types of fats, it’s not quite clear whether they’re beneficial or detrimental to our health.
Omega-6 fatty acids – found in nuts, seeds, and vegetable oils like sunflower, corn, cottonseed, and soybean oils – are linked to basically the opposite effects of omega-3’s, but it’s not clear if high omega-6, high omega-6:omega-3 ratio, or low omega-3 intake drives these effects (15,16,17).
Heated vegetable oils might also pose a problem, as they may oxidize easily, promoting inflammation (18).
Instead of cooking with vegetable oils, you might consider cooking with more stable extra virgin olive oil, coconut oil, avocado oil, or other high-oleic oils (19).
You’ll probably want to pay attention to how different types of fats affect you personally (with the help of a knowledgeable physician, if you want to keep an eye on blood lipids).
How much fat should I eat?
At the very least, you’ll probably want to get 20 – 35% of your calories from fat (22).
Beyond that, consider tinkering a bit to figure out how much fat helps you look, feel, and perform your best.
Multiple studies have shown that factors such as food quality and finding an approach you can maintain consistently are more important than how much relative fat or carbohydrate you eat.
A 2020 observational study of 37,000 people found that neither low-fat nor low-carbohydrate diets were superior for mortality risk, and that food quality appears to be a more important factor (23).
A 2018 randomized clinical trial found that participants achieved similar improvements in weight and health, regardless of whether they restricted carbohydrates or fats, when they prioritized minimally-processed foods and found an approach they could stick to consistently (24)
Trials in 2003, 2005, and 2009 all found that the relative fat, carbohydrate, and protein content of a diet do not appear to be as important for health improvements as finding an approach that you can maintain consistently (25,26,27).
You might start by prioritizing nutrient dense, minimally processed sources of fat like beef, lamb, eggs, nuts, seeds, olives, avocados, fatty fish a few times a week, and quality oils.
If you’re eating leaner cuts of meat, or very little fatty fish or eggs, you might want to add a thumb-sized serving or two of nuts, olives, avocado, or healthy oil to each meal.
If, on the other hand, you’re eating a lot of fattier cuts of meat, eggs, and fish, you might not need or want to add fat from nuts, olives, avocado, or healthy oils.
On that note, most of us aren’t very good at estimating or remembering how much or what we eat (28).
Tracking your food in a tool like Cronometer, and perhaps even weighing and measuring portions, for a bit might be a good idea to get an idea of how much fat you’re eating.
If you don’t like the idea of all this detailed measuring and record your food, that’s totally cool.
However, you might consider it as a temporary effort to build an intuitive feel for which foods offer which nutrients.
Experiment a bit with different relative levels of fat intake to find what works best for you.
As you dial up your fats, you’ll generally want to dial down your carbohydrates, and vice versa.
You might feel better with more carbohydrates and less fat.
You might feel better with more fat and less carbohydrates.
You might feel better with an even balance of the two.
Explore different sources of fat to see which ones one you enjoy eating.
Keep an eye also on how different fatty foods make you feel.
For example, do specific fats affect your appetite, heart rate, or even factors like swelling, bloating, or mental focus?
You might find a food journal to record your observations helpful in figuring this all out.
Only you can determine which fats and what amount work best for you.
This may not be an easy process.
It may take some time, effort, and patience.
You’re worth it, though.
You’ve got this.