Saturated vs Unsaturated Fats in Foods: Kitchen Sources and Label Rules

9 calories per gram: why fat types differ in structure, not energy density

As the UK National Health Service (NHS) and NIH MedlinePlus explain, dietary fat is an essential macronutrient that supplies essential fatty acids the body cannot make itself and enables the intestinal absorption of fat-soluble vitamins (vitamins A, D, E and K). Regardless of whether a fat is saturated or unsaturated, 1 gram of fat provides 9 kcal (37 kJ) of energy—more than double the 4 kcal (17 kJ) per gram provided by carbohydrates or protein.

What distinguishes one cooking fat from another is the proportion of fatty acid types inside it. No natural kitchen fat is 100% pure saturated or 100% pure unsaturated fat; instead, each oil, nut, seed or dairy fat has a characteristic ratio.

• Saturated fats: Typically solid or semi-solid at cool room temperature; predominant in butter, ghee, cheese, cream, coconut oil, palm oil and fatty cuts of meat. The FDA Daily Value for saturated fat is 20 g per day on a 2,000-calorie reference diet.
• Monounsaturated fats: Liquid at room temperature; predominant in olive oil, canola (rapeseed) oil,peanut oil, avocados, almonds, cashews and hazelnuts.
• Polyunsaturated fats: Liquid even when chilled; predominant in sunflower, safflower, corn, soybean and sesame oils, as well as walnuts, flaxseeds, chia seeds and oily fish (which supply omega-6 and omega-3 fatty acids).

How Total Fat, Saturated Fat and Unsaturated Fat appear on the Nutrition Facts label

Under U.S. Food and Drug Administration (FDA) Nutrition Facts labeling rules, packages must list Total Fat (current Daily Value: 78 g), Saturated Fat (current Daily Value: 20 g) and Trans Fat (no established Daily Value). Manufacturers may voluntarily list Polyunsaturated Fat and Monounsaturated Fat as indented sub-lines beneath Total Fat.

Because monounsaturated and polyunsaturated fats are voluntary lines on many packaged foods, the indented lines beneath Total Fat often do notappear to add up to the Total Fat gram number. Whenever a label lists 14 g Total Fat, 2 g Saturated Fat and 0 g Trans Fat without printing the unsaturated lines, the remaining 12 g per serving consists primarily of monounsaturated and polyunsaturated fats.

Trans fat on labels: partially hydrogenated oils vs natural ruminant dairy traces

As the FDA documents on its Trans Fat regulatory page, eating trans fat raises low-density lipoprotein (LDL, or "bad") blood cholesterol. Historically, most dietary trans fat came from partially hydrogenated oils (PHOs) created by industrial hydrogenation of liquid vegetable oils. In 2015, the FDA determined that PHOs are no longer Generally Recognized as Safe (GRAS) in human food, prohibiting their addition to most foods after June 18, 2018, with a final compliance date of January 1, 2021.

The FDA notes that small amounts of trans fat also occur naturally in foods from ruminant animals, such as milk, butter, cheese and meat, and were not affected by the PHO ban. When choosing fats for home cooking, MedlinePlus and the NHS recommend using unsaturated plant oils (such as olive, sesame, canola, sunflower or safflower oil) for everyday meals while keeping saturated fats within daily reference limits.

Sources & Classical References

1. UK National Health Service (NHS): Fat: the facts — Explains the role of dietary fat in absorbing fat-soluble vitamins, the 9 kcal (37 kJ) per gram energy density of all fats vs 4 kcal (17 kJ) for carbohydrates and protein, and food sources of saturated, monounsaturated and polyunsaturated fats.
2. NIH MedlinePlus: Dietary Fats — Summarizes dietary fat functions, LDL cholesterol effects of saturated and trans fats, the removal of partially hydrogenated oils (PHOs), and unsaturated cooking oil replacements.
3. FDA: Daily Value on the Nutrition and Supplement Facts Labels — Provides current FDA Daily Values for Total Fat (78 g) and Saturated Fat (20 g).