What do numbers like 16:1 or 22:1 mean

I’m trying to add the nutrients of specific food items to a spreadsheet, but for the fats I don’t understand what numbers such as 4:0 or 22:4 mean. Can someone please explain this to me?

Answer

The first number refers to the number of carbons in the fatty acid chain, and then second number refers to the number of double bonds. So anything with a 0 for the second number would be a saturated fatty acid. Anything with a 1 for the second number would be a monounsaturated fatty acid. And anything with 2, 3, 4, etc for the second number would be a polyunsaturated fatty acid.