So what if it's got 40% more calories? Use less. But fat vs. corn syrup should be a no-brainer -- HFCS is deadly. Fat will only really hurt you if you eat it to *excess*. Don't forget, fat, even if it is a lot of calories, is still *food*. High fructose corn syrup is a chemically modified saccharide that your body isn't designed to deal with correctly. Your brain, muscles, and everything else all work on *glucose*, which is one half of a sucrose molecule. The fructose does not burn directly. Ever. It must FIRST become storage fat, which must then be broken down and burned. So every time you suck down something with HFCS in it, that sweetener goes straight to your fat cells. Do not pass Go, do not collect 200 bucks.

But depending on what *kind* of fat was used to make your mayo, you might burn some of it first. Coconut oil, for example, is reputed to be a form of dietary fat that does not readily get stored, but instead burns almost like a carbohydrate.

Here's an example recipe.

http://www.passionatehomemaking.com/2009/07/homemade-coconut-oil-mayonnaise.html