The good fats are called unsaturated fats. They come in two main types: monounsaturated fats and polyunsaturated fats. Both are found primarily in plant foods and fish, and replacing saturated fat in your diet with these unsaturated fats can lower your risk of heart disease by up to 25% to 30%.
Your body breaks all dietary fat into smaller parts called fatty acids, which fall into two broad categories: saturated and unsaturated. The saturated kind has a rigid chemical structure and is typically solid at room temperature (think butter or the white fat on a steak). Unsaturated fats have a more flexible structure and are usually liquid at room temperature, like olive oil or canola oil. That flexibility at the molecular level translates into real differences inside your body.
Monounsaturated Fats
Monounsaturated fats are the type most people picture when they think of “healthy fat.” They’re found in high concentrations in olive oil (72% monounsaturated), avocados, canola oil, peanut oil, and nuts like almonds, hazelnuts, and pecans. Pumpkin and sesame seeds are also rich sources.
These fats lower harmful LDL cholesterol while helping maintain the beneficial kind. A Mediterranean-style diet rich in monounsaturated fat has been shown to improve blood vessel function and reduce blood clotting factors compared to a diet high in saturated fat. Research also suggests monounsaturated fats promote a higher rate of fat burning in the hours after a meal, which may help with weight management over time.
Polyunsaturated Fats
Polyunsaturated fats include the omega-3 and omega-6 fatty acids you’ve probably heard about. These are classified as essential fats, meaning your body cannot manufacture them on its own. You have to get them from food. Your body uses polyunsaturated fats to build cell membranes, coat nerve fibers, enable blood clotting, and control inflammation.
Eating polyunsaturated fats in place of saturated fats or refined carbohydrates reduces LDL cholesterol and lowers triglycerides. The American Heart Association notes that swapping just 5% of your daily calories from saturated fat to polyunsaturated fat is associated with a 25% lower risk of coronary heart disease, a reduction comparable to what cholesterol-lowering medications achieve.
Omega-3 Fatty Acids
Omega-3s are found in fatty fish (salmon, mackerel, sardines), walnuts, flax seeds, and canola and soybean oils. They’re best known for reducing triglycerides in the blood. In clinical trials, omega-3 supplementation lowered triglycerides by about 27% in people with elevated blood lipids. Omega-3s also shift LDL cholesterol particles from a small, dense form (which is more likely to clog arteries) to a larger, less harmful form.
The benefits extend well beyond cholesterol. Omega-3 fatty acids dampen inflammation throughout the body by suppressing the production of inflammatory signaling molecules and dialing down the activity of inflammatory immune cells. This anti-inflammatory effect has implications for heart disease, diabetes, and brain health. A large analysis combining 48 long-term studies with over 100,000 participants found that higher omega-3 intake was linked to roughly a 20% lower risk of dementia or cognitive decline. Each additional 0.1 grams per day of the omega-3s found in fish was associated with an 8% to 10% lower risk of cognitive decline.
Omega-6 Fatty Acids
Omega-6 fats are abundant in everyday cooking oils: soybean, corn, sunflower, safflower, sesame, and peanut oil. Linoleic acid, the primary omega-6, plays a key role in maintaining your skin’s moisture barrier by reducing water loss through the skin. It also helps regulate cholesterol levels and liver fat content.
Higher linoleic acid intake is associated with a lower risk of type 2 diabetes. The connection appears to involve improved insulin sensitivity: when cell membranes contain more unsaturated fat, they become better at responding to insulin and absorbing blood sugar. The protective effect becomes significant when omega-6 fats make up about 5.5% to 7% of total calorie intake.
How “Good” Fats Compare to “Bad” Fats
Saturated fats, found in red meat, butter, cheese, and coconut oil, raise LDL cholesterol when consumed in excess. Current dietary guidelines recommend keeping saturated fat below 10% of your daily calories and replacing it with unsaturated fats, particularly polyunsaturated fats.
Trans fats are the worst offenders. They raise harmful LDL cholesterol, lower protective HDL cholesterol, trigger inflammation, and increase insulin resistance. For every 2% of daily calories coming from trans fats, heart disease risk jumps by 23%. Trans fats were once common in margarine, shortening, and processed foods. Some older stick margarines contained up to 23% trans fat. While artificial trans fats have been largely removed from the food supply, small amounts still exist in some processed products, so checking labels is worthwhile.
Best Food Sources at a Glance
- Olive oil: 72% monounsaturated, 8% polyunsaturated, only 13% saturated
- Canola oil: 58% monounsaturated, 29% polyunsaturated, just 7% saturated
- Avocados: rich in monounsaturated fat with fiber and potassium
- Walnuts and flax seeds: among the best plant sources of omega-3s
- Fatty fish (salmon, sardines, mackerel): the richest source of the omega-3s EPA and DHA
- Sunflower and safflower oils: 66% to 74% polyunsaturated fat
- Almonds, hazelnuts, pecans: high in monounsaturated fat
Cooking With Healthy Fats
Not every healthy oil works at every temperature. Smoke point matters because once an oil starts to smoke, it breaks down and produces harmful compounds. High-quality extra virgin olive oil has a smoke point around 190°C to 207°C (374°F to 405°F), making it suitable for most sautéing and roasting. Refined avocado oil handles higher heat, with a smoke point of about 271°C (520°F), which makes it a good option for searing or stir-frying.
Keep in mind that smoke points drop as oils age or get reused. An oil that handled high heat perfectly when fresh will smoke at a lower temperature after it’s been opened for weeks or used for a previous batch of frying. Storing oils in a cool, dark place and not reusing cooking oil multiple times helps preserve their stability and nutritional value.