Good fats are unsaturated fats, the kind that are liquid at room temperature and improve your heart health rather than harm it. They come in two main forms: monounsaturated and polyunsaturated. Both lower harmful LDL cholesterol, reduce inflammation, stabilize heart rhythms, and help prevent insulin resistance. The key isn’t eating less fat overall but eating the right kinds.
Monounsaturated Fats
Monounsaturated fats are found in olive oil, avocados, almonds, cashews, peanuts, and sesame seeds. They’re the cornerstone of the Mediterranean diet, which consistently ranks among the healthiest eating patterns studied. In the OmniHeart trial, replacing carbohydrate-rich foods with monounsaturated fats lowered blood pressure, improved cholesterol profiles, and reduced overall cardiovascular risk.
These fats are especially effective at lowering LDL cholesterol. In one controlled study, people on a diet rich in monounsaturated fat saw their LDL cholesterol drop by nearly 18%. Monounsaturated fats also appear to suppress the hunger hormone ghrelin more quickly after a meal than other fat types, which may help with feeling satisfied between meals.
Polyunsaturated Fats
Polyunsaturated fats include the omega-3 and omega-6 fatty acids your body can’t make on its own. You have to get them from food. These fats are found in fatty fish, walnuts, flaxseeds, chia seeds, sunflower seeds, and soybean oil. In the same study that tracked monounsaturated fat, a polyunsaturated-fat-rich diet lowered LDL cholesterol by about 13%.
Where polyunsaturated fats really stand out is in the brain. Fat-based molecules make up roughly 60% of the brain’s dry weight, and they’re even more concentrated at the junctions where brain cells communicate. After birth, the growth and insulation of nerve fibers depends heavily on long-chain polyunsaturated fats. They also stimulate the creation of new neurons in the hippocampus, the brain region central to memory.
Omega-3s: The Most Talked-About Good Fat
Omega-3 fatty acids get special attention because most people don’t eat enough of them. There are three main types. ALA comes from plant sources like flaxseeds, chia seeds, and walnuts. EPA and DHA come primarily from fatty fish such as salmon, mackerel, sardines, and herring. Your body can convert a small amount of ALA into EPA and DHA, but the conversion is inefficient, which is why eating fish directly matters.
DHA is concentrated in the brain, retina, and sperm cells. EPA and DHA together shift the body’s inflammatory balance toward less inflammation, lower triglyceride levels, and support heart health, particularly for people who don’t get much omega-3 from their regular diet. For cognitive function, a large Norwegian study of over 2,000 healthy older adults found that eating about 75 grams of fish per day (roughly two fish meals per week) was the threshold for optimal brain performance. Eating more than that didn’t add further benefit.
The adequate daily intake for ALA is 1.6 grams for adult men and 1.1 grams for adult women. A tablespoon of ground flaxseed or a small handful of walnuts covers that easily. During pregnancy, the recommendation rises to 1.4 grams, and research shows long-chain omega-3 supplementation reduced the risk of early preterm birth by 42%.
The Omega-6 to Omega-3 Balance
Omega-6 fats aren’t bad. They’re essential, found in vegetable oils, nuts, and seeds, and your body needs them for normal cell function. The problem is proportion. For most of human history, people ate omega-6 and omega-3 fats in roughly a 4-to-1 ratio. The modern Western diet has pushed that to about 20-to-1, overwhelmingly favoring omega-6. This imbalance is linked to higher rates of inflammation, autoimmune conditions, and allergies.
You don’t need to obsess over the exact ratio. The practical fix is straightforward: eat more omega-3-rich foods (fish, flaxseeds, walnuts) and use fewer highly refined vegetable oils like corn and soybean oil, which are the biggest sources of excess omega-6 in most diets.
What Makes a Fat “Bad” by Comparison
Saturated fats, found in red meat, butter, cheese, and coconut oil, raise LDL cholesterol. The U.S. Dietary Guidelines recommend keeping saturated fat below 10% of your daily calories. For someone eating 2,000 calories a day, that’s about 22 grams, or roughly three tablespoons of butter. Replacing even a portion of those saturated fats with unsaturated fats improves your total-to-HDL cholesterol ratio, one of the strongest predictors of heart disease risk.
Trans fats, once common in margarine and processed foods, are the worst type. They raise LDL, lower HDL, and increase inflammation simultaneously. Artificial trans fats have been largely banned in the U.S. food supply, but small amounts can still appear in products with partially hydrogenated oils on the label.
Best Food Sources at a Glance
- Olive oil: Rich in monounsaturated fat. The go-to for dressings and cooking.
- Avocados: High in monounsaturated fat plus fiber and potassium.
- Salmon and sardines: Top sources of EPA and DHA omega-3s.
- Walnuts: One of the few nuts high in ALA omega-3s.
- Flaxseeds and chia seeds: Concentrated plant-based ALA sources.
- Almonds and peanuts: Primarily monounsaturated fat with protein.
- Sunflower seeds: Good source of polyunsaturated fat and vitamin E.
Cooking with Healthy Oils
Not every healthy oil works for every cooking method. The key factor is the smoke point, the temperature at which an oil starts to break down and lose its nutritional value. Avocado oil has the highest smoke point among common healthy oils at 520°F, making it ideal for searing and stir-frying. Virgin olive oil handles medium-high heat well at around 420°F, and despite a common myth that it can’t handle cooking, olive oil is actually more stable during heating than many other oils due to its antioxidant content.
Walnut oil has a smoke point of 400°F but goes rancid faster than other oils because of its high polyunsaturated fat content. Store it in the refrigerator. The same goes for flaxseed oil, which is best used cold in dressings or smoothies. For all oils, the enemies of freshness are heat, air, and light. Keep them sealed in a cool, dark place.
How Good Fats Help with Fullness
Fat is the most calorie-dense nutrient at 9 calories per gram, compared to 4 for protein or carbs. But that density is part of why it keeps you full. Meals with adequate healthy fat slow digestion and trigger gut hormones that signal satiety. Research comparing monounsaturated and polyunsaturated fat meals found that both suppressed hunger hormones, with monounsaturated fats acting faster in the first hour after eating and polyunsaturated fats potentially sustaining satiety control over a longer window.
This is why very low-fat diets often backfire for weight management. People feel hungrier, eat more refined carbs to compensate, and end up in a worse metabolic position. Including a source of healthy fat at each meal, a drizzle of olive oil on vegetables, a quarter of an avocado on toast, a handful of nuts as a snack, helps regulate appetite without requiring you to count every calorie.