The Skinny on Fat

Fat is essential in our diet so the no fat trend never made much sense to me. The wisdom for at least the past 50 years to get the essential fat needed is for 30% of your calories to come from fat in your diet (10% unsaturated, 10% polyunsaturated, and 10% saturated). Practically speaking, this means that if an oil is liquid at room temperature, like olive oil, it can be considered mostly unsaturated and if it's solid, like butter or the fat in meat, it can be considered mostly saturated. Fats in foods are a combination of fats that are unsaturated and saturated to different extents. Since fats that are the most saturated are hardest at room temperature, it's easy to know how to get a range in your diet by looking at your food. Just stay away from any packaged foods that have trans fats on the label or are those listed at partially hydrogenated which is the chemical process of saturating a fat to stabilize it for a longer shelf  life, to change the texture or some functional property. Over the next few years (by 2018) these trans fats will be eliminated from all products.

Since the average American diet was traditionally high in meat and cheese (both containing fat solid at room temperature), the government's message from the 80's until recently has been to eat a low fat diet. The erroneous assumption was that fat in food eaten resulted in more solid fat blocking our arteries and everywhere else we don't want it to be. That seemed counter intuitive to me for several reasons. First, body temperature is much higher than room temperature by at least 20 degrees. Second, the body digests fat and has its own regulation system so the amount of body fat stored is regulated by other than the fat amount consumed.

A few more facts to know about the fat we consume are key to understand. Fat has more than twice the calories of either protein or carbohydrates for each gram consumed. Therefore, to eat the 30% of calories as fat, you will consume less than half the amount of a carbohydrate, such as a potato, by weight. The latest "eat more fat" advocates make several assumptions which may or may not apply to your own diet. For starters, they assume that you are currently eating a very low fat diet (much lower than 30%) and a high carbohydrate diet (with a high sugar content). If you were buying lots of no fat and low fat products and we're still eating the same amount of food, you were likely eating a higher carbohydrate diet. They also assume when you do consume 30 or even 40% of your calories as fat in your diet you will be full and won't want to eat more fat or for that matter anything else. That would be great, but people overeat all the time and if they hear the titles of the books as permission to as eat as much fat as they want as the way to get thin, I expect that obesity in this country will continue as people start eating many more calories as a result of increasing fat in their diet.

The best diet is one that is varied and balanced. Eat whole foods you enjoy with others when possible, pay attention to when you are hungry or feel full and most of all, relax. You know when you feel good and how to eat well so listen well to your body. Only then will you get the answers that are right for you.