Fat Guide
Saturated vs. unsaturated fat: what's actually the difference
Not all fat behaves the same way in your body — the difference comes down to a detail in the fat molecule's chemical structure.
The chemistry, briefly
Fat molecules are chains of carbon atoms. In saturated fat, every carbon is bonded to as many hydrogen atoms as possible — no double bonds — which makes the molecule straight and lets it pack tightly (this is why saturated fats like butter are solid at room temperature). Unsaturated fats have one or more double bonds, which kinks the chain and keeps it liquid at room temperature — like olive oil.
Health associations and food sources
Saturated fat
Found in butter, fatty cuts of meat, cheese, and coconut oil. Research reviewed by Harvard's Nutrition Source associates replacing saturated fat with unsaturated fat with improved blood cholesterol profiles.[1] Most guidelines suggest keeping saturated fat intake moderate rather than eliminating it.
Unsaturated fat
Found in olive oil, avocado, nuts, seeds, and fatty fish. Includes both monounsaturated fats (olive oil, avocado) and polyunsaturated fats (fish, walnuts, sunflower oil) — the latter includes the essential omega-3 and omega-6 fatty acids.
There's a third category worth knowing: industrially-produced trans fat, which behaves differently from both and is best minimized. Read what trans fat is and why it was banned.
Keep reading: Healthy high-fat foods · What is trans fat? · What fat actually does