WHEN you think of fat, you probably think of foods that have a lot of fat, or people who do. After a few years with some extra pounds, the only thing you know about fat is that you’re tired of it and want to get rid of it forever. But it’s probably one of your body’s most misunderstood dietary nutrients, stemming from a widely held but misguided belief that fat should take much of the blame for our obesity epidemic.
In 1980s, that U.S. government released nutritional guidelines that essentially said we should base our diets on potatoes, rice, cereal, and pasta and minimize the foods with a lot of fat and protein. That gave way to the idea that fat makes you fat. In 1998, for example, two prominent obesity researchers estimated that if you took only 10 percent of your calories from fat, you’d lose 16 grams of fat a day–a loss of 50 pounds in a year. But when a Harvard epidemiologist, Walter Willett, tried to find evidence that this occurred, he couldn’t find any link between people who lost weight and the fact that they were on a low-fat diet. In fact, in some studies lasting a year or more, groups of people showed weight gains on low-fat diets. Willett speculated that there was a mechanism responsible for this. When the body is on a low-fat diet for a long period, it stops losing weight.
Part of the reason our bodies rebel against low-fat diets is that we need fat. For instance, fat plays a vital role in the delivery of vitamins A, D, E and K, nutrients stored in fatty tissue and the liver until your body needs them. Fat also helps produce testosterone, which helps trigger muscle growth. And fat, like protein, helps keep you satisfied and controls your appetite. In fact, if we’ve learned anything about weight loss over the past several years, it’s that reducing your fat intake doesn’t necessarily do a darn thing to decrease your body fat. One study for instance, compared a high-carbohydrate diet and a high-fat diet. The researchers found that the group with the high-fat diet experienced less muscle loss than the other group. The researchers theorized that muscle protein was being spared by the higher-fat diet because fatty acids, more so than carbs, were being harnessed and used for energy.
The truth is that reasonable amounts of fat can actually help you lose weight. In a study from the International Journal of Obesity, researchers at Boston’s Brigham and Women’s Hospital and Harvard Medical School put 101 overweight people on either a low-fat diet (fat was 20 percent of the total calories) or a moderate-fat diet (35 percent of calories) and followed them for 18 months. Both groups, lost weight at first, but after a year and a half, the moderate-fat group had lost an average of 9 pounds per person, whereas the low-fat dieters had gained 6 pounds. The results suggest that a healthy amount of fat is a factor in keeping your weight under control.
Trans fats were invented by grocery manufacturers in the 1950s as a way of appealing to our natural cravings for fatty foods. But there’s nothing natural about trans fats. They’re cholesterol-raising, heart-weakening, diabetes-causing, belly-building chemicals that, didn’t even exist until the middle of the last century. In one Harvard study, researchers found that getting just 3 percent of your daily calories from trans fats increased your risk of heart disease by 50 percent. Three percent of your daily calories equals about 7 grams of trans fats that’s roughly the amount in a single order of fries.
To understand what trans fats are, picture a bottle of vegetable oil and a stick of margarine. At room temperature, the vegetable oil is a liquid, the margarine a solid. Now, if you baked cookies using vegetable oil, they are greasy. And who would want to buy a cookie swimming in oil? So to create cookies and cakes, nachos, chips, pies, muffins doughnuts, waffles and many, many other foods we consume daily, manufacturers heat the oil to very high temperatures and infuse it with hydrogen. That hydrogen bonds with the oil to create an entirely new form of fat–trans fat, that stays solid at room temperature. Vegetable oil becomes margarine. And now foods that might normally be healthy, but maybe not as tasty, become fat bombs.
Since these trans fats don’t exist in nature, your body has a hell of a time processing them. Once consumed, trans fats are free to cause all sort of mischief inside you. They raise the number of LDL(bad) cholesterol particles in your bloodstream and lower your HDL(good) cholesterol. They also raise blood levels of other lipoproteins. The more lipoprotein you have in your bloodstream, the greater your risk of heart disease. Increased consumption of trans fats has also been linked to increased risk of diabetes and cancer.
Trans fats are added to a shocking number of foods. They appear on food labels as Partially Hydrogenated Oil, usually vegetable or palm oil. Check the ingredient labels on all the packaged foods you buy, and if you see Partially Hydrogenated Oil on the label, consider finding an alternative. You might not be able to avoid trans fats entirely, but you can choose foods with a minimal amount of the stuff.
The other way to avoid trans fats is to avoid ordering fried foods. Because trans fats spoil less easily than natural fats and are easier to ship and store, almost all fried commercial foods are now fried in trans fats rather than natural oils. Fish and chips, tortillas, fried chicken, all of it is packed with belly-building trans fats. Order food baked or broiled whenever possible.