Saturated vs unsaturated fat

All fats have 9 calories per gram, but they don't all act the same way in your body. The main difference is between saturated fats, which raise LDL ("bad") cholesterol, and unsaturated fats, which can help lower it when they replace saturated fat.

By the Calcist team · Updated October 29, 2026 · About a 3-minute read

The difference in one table

	Saturated fat	Unsaturated fat
At room temperature	Usually solid (butter, lard)	Usually liquid (olive oil, canola oil)
Main sources	Fatty meats, butter, cheese, cream, whole milk, ice cream, lard, tallow, coconut and palm oils	Olive, canola, sunflower, safflower, corn and soybean oils, nuts, seeds, avocados, fish
Effect on LDL cholesterol	Raises it	Can help lower it when it replaces saturated fat
Calories per gram	9	9

What makes a fat saturated?

Fats are made of chains of carbon atoms. In a saturated fat, every carbon in the chain carries as many hydrogen atoms as it can: it's "saturated" with hydrogen, and the chain has no double bonds. That lets the straight chains pack tightly together, which is why saturated fats tend to be solid at room temperature.

Unsaturated fats have one or more double bonds. A monounsaturated fat has one; a polyunsaturated fat has two or more. The double bonds put bends in the chain, so the molecules can't pack as tightly, and the fat stays liquid at room temperature. Real foods contain a mix of all three types; we call a food "saturated" or "unsaturated" by which type it has most of.

Monounsaturated fats

Monounsaturated fats are found in plant foods such as nuts, avocados and vegetable oils. Olive, canola, sunflower, sesame and peanut oils are good sources. They're liquid at room temperature but start to harden when chilled. Eaten in place of saturated fat, they can help lower LDL cholesterol.

Polyunsaturated fats, including omega-3s

Polyunsaturated fats are found in walnuts, sunflower seeds, flax seeds and flax oil, fish, and corn, soybean and safflower oils. They include the omega-3 and omega-6 fatty acids, which your body needs but can't make. Fish such as salmon, mackerel, herring, albacore tuna and trout, along with walnuts and flax, provide omega-3s. Like monounsaturated fats, polyunsaturated fats can help lower LDL cholesterol when they replace saturated fat.

Trans fat: the one to avoid

Artificial trans fat is made when liquid oils are partly hydrogenated to make them solid, producing partially hydrogenated oils. Trans fat raises LDL cholesterol and lowers HDL ("good") cholesterol. The FDA has banned manufacturers from adding partially hydrogenated oils to foods, but you can still check the label: look at the trans fat line and for "partially hydrogenated" in the ingredients. Small amounts of trans fat occur naturally in meat and dairy.

How much saturated fat is OK?

The Dietary Guidelines for Americans, 2025–2030, say that in general, saturated fat should not exceed 10% of daily calories. On a 2,000-calorie diet, that's 200 calories, or about 22 grams, because 200 ÷ 9 = 22.2. The FDA's Daily Value on nutrition labels is less than 20 grams. The American Heart Association suggests a stricter aim of under 6% of calories, about 13 grams on 2,000 calories.

To find your own limit, use the saturated fat calculator. On a label, 5% Daily Value or less per serving is low and 20% or more is high.

It's worth knowing that the science is still developing. The 2025–2030 guidelines themselves say more high-quality research is needed to determine which types of dietary fats best support long-term health. They emphasize fats that come in whole foods, such as omega-3-rich seafood, nuts, seeds, olives and avocados, and name olive oil as a cooking oil to prioritize. They also note that significantly limiting highly processed foods, a major source of saturated fat, helps meet the 10% goal.

Simple swaps

Cook with olive or canola oil instead of butter or lard.
Snack on nuts or seeds instead of chips or cookies.
Choose fish, beans, lentils or skinless poultry more often in place of fatty meats.
Use avocado or nut butter on toast.

Don't forget the calories

Swapping saturated for unsaturated fat changes the type of fat, not the calories. Gram for gram, the fat in olive oil has the same 9 calories as the fat in butter. To see how fat fits into your total, try the macronutrient calories calculator.

If you've been told you have high cholesterol or heart disease, ask your doctor or a registered dietitian what limit is right for you.

Sources

MedlinePlus (NIH): Dietary fats explained
MedlinePlus (NIH): Facts about monounsaturated fats
MedlinePlus (NIH): Facts about polyunsaturated fats
MedlinePlus (NIH): Facts about trans fats
USDA and HHS: Dietary Guidelines for Americans, 2025–2030 (January 2026)
FDA: Interactive Nutrition Facts Label, saturated fat — Daily Value under 20 g; 5% DV is low and 20% DV is high.
American Heart Association: Saturated fat — less than 6% of calories, about 13 g on 2,000 calories.

Questions people ask

What is the difference between saturated and unsaturated fat?

Saturated fats are usually solid at room temperature and raise LDL cholesterol. Unsaturated fats are usually liquid and can help lower LDL when they replace saturated fat.

Which foods are high in saturated fat?

Fatty meats, butter, cheese, cream, whole milk, ice cream, lard and tallow, and coconut, palm and palm kernel oils.

Which foods are high in unsaturated fat?

Olive, canola, sunflower, corn and soybean oils, nuts, seeds, avocados and fish such as salmon and mackerel.

How much saturated fat should I eat a day?

Under 10% of calories, per the Dietary Guidelines: about 22 grams on 2,000 calories. The American Heart Association suggests under 6%, about 13 grams.

Is unsaturated fat lower in calories?

No. All fats have 9 calories per gram.