In the 1980s, the advice for losing weight was simple: cut the fat. Food companies responded with low-fat versions of everything, and when you take fat out of a food, something has to replace it, usually sugar and refined starch. Obesity rates kept climbing anyway. The lesson wasn't that fat makes you thin. It's that the type of fat, and what you eat instead, matters a lot more than the low-fat era assumed.
Does eating fat make you fat?
Not on its own. Weight gain comes from eating more energy than you use, from any source. Fat is calorie-dense, so portions still matter, but fat also slows digestion and helps meals feel satisfying, which can make it easier to eat sensibly. Swapping fat for sugary, refined "low-fat" foods tends to do the opposite.
Healthy fats also help with fullness signals. In a study of healthy adults, a meal made with olive oil produced higher levels of the fullness hormone GLP-1 than the same meal made with butter.
Which fats are actually good for you?
The research points clearly toward unsaturated fats from plants. A Cochrane review of randomized trials found that cutting saturated fat for at least two years reduced cardiovascular events, and that replacing it with polyunsaturated fat was a useful swap. In the PREDIMED trial, people at high cardiovascular risk who ate a Mediterranean diet with extra olive oil or nuts had about 30% fewer major cardiovascular events than those told to follow a reduced-fat diet.
The best healthy fats to eat
Avocados
Avocados are rich in monounsaturated fat and also bring fiber and potassium. Mash one onto toast, slice it into salads or blend it into a smoothie for a creamy texture.
Extra-virgin olive oil
Olive oil is the backbone of the Mediterranean diet and one of the best-studied fats there is. Use it for cooking, dressings and drizzling over vegetables.
Nuts and seeds
Walnuts, almonds, chia seeds, flaxseeds and hemp seeds supply unsaturated fats, protein and fiber. Walnuts, chia and flax are also good sources of ALA, the plant omega-3. A small handful a day is an easy habit.
Algae-based DHA
Your body converts only a small amount of ALA into DHA, the omega-3 your brain and eyes rely on. In a review of trials, high-dose flaxseed oil did not raise blood levels of EPA and DHA, while algal oil did. Fish get their DHA from algae, and you can go straight to the source: Head & Heart provides 500 mg of DHA from algae, not fish. Learn more about the difference between ALA, EPA and DHA.
What about coconut oil and MCT oil?
Coconut oil has a healthy reputation, but it's mostly saturated fat. A meta-analysis of clinical trials found that coconut oil raised LDL ("bad") cholesterol by about 10 mg/dL compared with non-tropical vegetable oils, with no benefit for body fat, blood sugar or inflammation.
MCT oil is a different product. It's made from medium-chain triglycerides, and a meta-analysis found that replacing other fats with MCTs led to small reductions in body weight. Coconut oil contains some MCTs, but the results for pure MCT oil don't carry over to it. Enjoy coconut oil for flavor now and then, and use olive oil as your everyday fat.
What about butter?
Butter, including grass-fed butter, is high in saturated fat, which is what the Cochrane review found worth reducing. You don't have to avoid it completely, but it isn't a fat-burning food. Plant oils, nuts, seeds and avocado are the better daily choices.
Easy ways to add healthy fats
- Cook with extra-virgin olive oil instead of butter.
- Add a spoonful of chia or ground flax to oatmeal or smoothies.
- Keep a jar of unsalted nuts or seeds within reach for snacks.
- Top salads, grain bowls and toast with avocado.
- Pair carbs with a little fat and protein so meals keep you full longer.
Going plant-based? Read how to get vegan omega-3, or see how fat fits into a vegan keto diet.
