The fat-free era of the 1990s may be a distant memory, but the conversation around dietary fat is still muddier than it needs to be. With several distinct types of fat each behaving differently in the body knowing what to eat, what to limit, and what to avoid entirely is less straightforward than a single grocery label can communicate.
Three registered dietitians cut through the noise to explain what actually separates the good from the bad, where the science currently stands, and which fats deserve a more prominent place on most people’s plates.
What makes a fat good
Unsaturated fats are broadly considered the beneficial category, and for good reason. They support brain function, nerve health, cardiovascular health, cellular function, and the body’s ability to manage inflammation. This group breaks down into two subtypes: monounsaturated fats and polyunsaturated fats, and both earn their place in a balanced diet.
Monounsaturated fats are found in foods like olive oil, avocados, peanuts, and most other nuts. Research has linked olive oil intake to a reduced risk of several chronic diseases, including heart disease and type 2 diabetes. A 2025 study also found higher monounsaturated fat consumption to be associated with lower stroke risk a finding that has added to the already strong case for Mediterranean style eating patterns.
Polyunsaturated fats, meanwhile, get considerable attention because they include the omega fatty acids a group the body cannot manufacture on its own and must obtain through food. Omega 3s, found in fatty fish like salmon and sardines as well as seeds like flaxseed, chia, and hemp hearts, support anti-inflammatory processes and cognitive function. Omega 6s, found in sunflower oil, soybean oil, and eggs, play a role in brain function, hormone production, and skin health. Both are considered essential, and both are necessary just in different amounts.
What makes a fat bad
Two fat categories fall on the less favorable end of the spectrum: trans fats and saturated fats. They are not equally harmful, but both warrant attention.
Trans fats are considered the most damaging type of dietary fat available. Created through a process called hydrogenation in which hydrogen atoms are added to fat molecules they raise LDL (low-density lipoprotein) cholesterol while simultaneously lowering HDL (high density lipoprotein) cholesterol, delivering a two part blow to heart health. They appear in some fried foods, older margarine products, and certain commercially baked goods. One important labeling note: a product can legally state it contains zero grams of trans fat if the amount per serving is below 0.5 grams. Checking the ingredient list for the term partially hydrogenated oil is the more reliable way to confirm their absence.
Saturated fats, found in fatty cuts of meat, skin on poultry, full fat dairy, baked goods, chocolate, coconut oil, and palm oil, have a more complicated story. The long standing guidance to keep them low because they raise LDL cholesterol and contribute to arterial inflammation remains generally sound. However, a major 2025 meta analysis found that people at low to moderate cardiovascular risk may not see a meaningful benefit from aggressively cutting saturated fat. Some researchers point to individual differences in how people metabolize these fats, as well as the varying effects of specific saturated fatty acids. Stearic acid, for example, has shown certain neutral or even positive effects in the body.
Still, because most saturated fat-containing foods contain multiple types of saturated fatty acids including those with a documented negative impact on cholesterol the general recommendation to keep intake below 10% of daily calories remains the prudent standard. The American Heart Association applies a stricter ceiling of 6%.
The fats most worth focusing on
Among all the beneficial fat options available, dietitians point to polyunsaturated fats and omega 3s in particular as the most impactful category for most people to prioritize. Omega 3s support longevity, heart protection, immune function, and the maintenance of healthy brain tissue, all while most Americans fall significantly short of adequate intake.
Omega 6 fatty acids also deserve a more nuanced reputation than they typically receive. Though sometimes labeled pro inflammatory, the science does not support that framing at a broad level. High intake of omega 6s like linoleic acid is generally not associated with increased inflammation in human studies and is frequently linked to better overall health outcomes.
Monounsaturated fats also earn a strong mention, particularly olive oil. The landmark PREDIMED trial one of the largest nutrition studies ever conducted found that a Mediterranean diet supplemented with extra virgin olive oil reduced major cardiovascular events by roughly 30% compared to a low fat diet. A 2024 Harvard study found a reduced risk of dementia related mortality with as little as half a tablespoon per day.
How to build a fat friendly plate
The most practical approach is variety rather than obsession over any single source. All dietary fats including the less favorable ones support the body’s absorption of fat soluble vitamins A, D, E, and K, making blanket elimination a counterproductive strategy.
Pairing fat containing foods with vegetables, fruits, lean proteins, legumes, nuts, and seeds creates the kind of balanced eating pattern that does the most good over time. The goal is not perfection. It is the consistent, informed choices that collectively reduce the risk of chronic disease.
