Two types of dietary fat are consistently linked to health problems: trans fats (especially the artificial kind) and excess saturated fat. Trans fats are the worst offenders, and most have been banned from the food supply. Saturated fat is more nuanced, but eating too much of it raises cholesterol and increases your risk of heart disease.
Trans Fats: The Worst Type
Artificial trans fats are created when manufacturers pump hydrogen into vegetable oils to make them solid at room temperature. This process, called partial hydrogenation, once made oils cheaper and gave processed foods a longer shelf life. The health consequences were severe: trans fats raise your “bad” LDL cholesterol, lower your “good” HDL cholesterol, and significantly increase heart disease risk.
The FDA determined in 2015 that partially hydrogenated oils are no longer safe for use in food. Manufacturers had until January 1, 2021 to fully comply, and in 2023 the FDA removed the last remaining regulatory references to these oils. So if you’re eating in the United States, artificial trans fats have been largely eliminated from the food supply. Many other countries have followed suit.
A small amount of trans fat occurs naturally in beef, lamb, and dairy products. These natural trans fats behave somewhat differently in the body, and the available evidence doesn’t show a substantial difference in harm compared to the artificial kind, but people consume them at much lower levels. At the small amounts found in a normal diet, naturally occurring trans fats aren’t considered a major concern.
Saturated Fat: The One to Watch
Saturated fat is the type most people still need to manage. It raises levels of cholesterol in your blood, and elevated blood cholesterol is a well-established driver of heart disease. Some meta-analyses have claimed the link between saturated fat and heart disease is weak, but those studies adjusted for cholesterol in their calculations. Since cholesterol is the very mechanism through which saturated fat causes problems, adjusting for it masks the real effect. When researchers account for this error, the association holds up clearly.
Beyond cholesterol, saturated fat may promote low-grade inflammation. Population studies have found that higher intake of certain saturated fatty acids (particularly those concentrated in coconut oil and full-fat dairy) is associated with elevated levels of C-reactive protein, a blood marker of inflammation, at least in men. Chronic inflammation is tied to heart disease, type 2 diabetes, and other long-term conditions.
Saturated fat also affects how your body handles blood sugar. In animal studies, high-fat diets (whether from saturated or unsaturated sources) led to a two- to threefold increase in liver fat and reduced the liver’s ability to respond to insulin by 60 to 75 percent. When your liver stops responding properly to insulin, blood sugar regulation suffers, setting the stage for metabolic problems over time.
How Much Saturated Fat Is Too Much
The World Health Organization recommends that no more than 10 percent of your total daily calories come from saturated fat. For someone eating 2,000 calories a day, that works out to about 22 grams. The American Heart Association sets an even stricter target of 5 to 6 percent for people who need to lower their cholesterol, which is roughly 11 to 13 grams on a 2,000-calorie diet.
Those numbers are easy to exceed without realizing it. A single cup of diced cheddar cheese contains about 25 grams of saturated fat, already over the WHO’s daily limit. A cup of heavy whipping cream has roughly 28 grams. A fast-food breakfast sandwich with egg, cheese, and sausage packs around 14 grams in one sitting. Even foods that don’t seem fatty can add up: a frozen deep-dish pie crust alone has about 18 grams, and a cup of dried sweetened coconut flakes has over 22 grams.
Where Saturated Fat Hides
The biggest sources in most people’s diets are full-fat cheese, red meat (especially fattier cuts like pork shoulder and beef with visible fat), butter, cream, and coconut products. Processed meats like salami contribute meaningful amounts as well, with about 10 grams in a three-ounce serving. Chicken skin, often overlooked, carries nearly 14 grams of saturated fat per four-ounce portion.
Baked goods and desserts are another major source. Chocolate mousse, pie crusts, and confectionery coatings all rank among the most saturated-fat-dense foods in the USDA database. Because these foods combine saturated fat with sugar and refined flour, they represent a double hit to metabolic health.
What to Eat Instead
Replacing saturated fat matters more than simply cutting it out. What you replace it with determines whether your health actually improves. A systematic review of dietary fat trials found that swapping saturated fat for polyunsaturated fat (the kind in fish, walnuts, flaxseeds, and vegetable oils like sunflower and soybean) reduced death from cardiovascular disease by 28 percent for every 5 percent of calories replaced. Monounsaturated fats, found in olive oil, avocados, and most nuts, were equally effective at lowering heart disease events.
Replacing saturated fat with whole grains also lowers heart disease risk. But replacing it with sugar or refined starch actually increases risk. This is a critical distinction: a “low-fat” cookie made with extra sugar is not an improvement over a moderate-fat meal built around olive oil and whole grains.
In practical terms, this means cooking with olive or avocado oil instead of butter, choosing fish or poultry over fatty red meat a few times a week, snacking on nuts instead of cheese, and reading labels on packaged foods where coconut oil and palm oil (both high in saturated fat) often appear as cheap ingredients.
Unsaturated Fats Are Not the Enemy
It’s worth being clear: fat itself is not bad. Your body needs it to absorb vitamins, build cell membranes, and produce hormones. The two types of unsaturated fat, polyunsaturated and monounsaturated, actively protect your cardiovascular system when they replace saturated fat in your diet. Omega-3 fatty acids, a type of polyunsaturated fat found in salmon, sardines, and flaxseeds, are especially well-supported for reducing inflammation and heart disease risk.
The goal isn’t a low-fat diet. It’s shifting the balance so that most of the fat you eat comes from unsaturated sources, saturated fat stays under 10 percent of your calories, and artificial trans fats stay at zero.