In simple terms, fats are long chains of carbon atoms. Picture a string of pearls. The fats that we eat have the carbon at one end modified into an acid molecule. That allows them to be attached like strings to a glycerin molecule, which is essentially half of a sugar molecule. A glycerin molecule can hold three fat molecules, hence the term triglyceride, which is one of the things we measure when checking your cholesterol levels. Three fats on a glycerin.
Fats can either be saturated – all of the places on the carbon backbone that can have an atom stuck to them have a hydrogen atom attached – or unsaturated – some of the hydrogens are not there. When they are left off of adjacent carbons, those sites attach to each other in a double bond. Those are weak spots in the carbon chain. Polyunsaturated fats have many more double bonds, tend to be liquid at room temperature, and break down more easily. When they break, oxygen attaches to them and they may smell and taste horrible. We call that rancid. Food makers create hydrogenated fats by attaching hydrogen atoms to those weak places, thus getting rid of the double bonds. Foods made with the hydrogenated fats have a longer shelf life. Unfortunately this process creates what we call trans fats: The bonds between the atoms are not lined up quite the way nature would prefer them to be, and it turns out that those are really bad for us.
When we eat fats, our bodies’ enzymes break them down to create energy or other molecules that you need. Those enzymes work well on fats created in nature by other enzymes. When they are not lined up right, as in trans fats, they are a lot harder for our bodies to process. When we cook with fats at high enough temperatures that they smoke, we are breaking those double bonds. When they come back together they can reform in the trans shape. The fat has been changed from something wholesome to something that is bad for us. Eating trans fat increases our risk of heart, vascular and brain disease.
Animals like you and me can make certain fats, which is why all those fat-free goodies turn into butts and tummies, but we can’t make all of the important types of fats. The ones that we need but can’t make are called essential fatty acids. Those are mostly made by plants. Another good reason to eat them. These are the omega-3 and omega-6 fatty acids that you have heard about. Omega-3 means that the double bond is the third one from the end of the fat. They are made by algae in the sea and plants on the land, and get passed up the food chain. This is why wild seafood and pasture-fed meats are better for us. Those essential fats are made into compounds critical for cellular and brain health.
So go ahead and call me a fat head. It’s true.
Dr. Bob Riggs is a family medicine physician practicing at Group Health’s Riverfront Medical Center.
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