The Truth About Fats, Proteins and Carbohydrates

Sometimes termed "macronutrients," fats, proteins and carbohydrates form the bulk of our nutritional intake. All three are necessary to the functioning of the human body. Without any one of them, we would die. Yet myths and misinformation about each of them are everywhere, and it can be nearly impossible sorting out good information from bad. Are there really "good carbs" and "bad carbs?" If fats are necessary, why are low-fat diets all the rage? And can you really never get enough protein?

Fats have gotten a bad rap over the past couple of decades, but the science on fats is beginning to show them in a far better light. Cells cannot function without fats, and fats are required for the absorption of several necessary vitamins, known as "fat-soluble vitamins." Some types of fatty acids cannot be made by the body and must be consumed in food. Some types of fats have been called "good fats" or "bad fats," but except for artificial trans fats, no fats have been proven to have a strictly harmful effect. Our bodies seem to benefit from all types of fats, if they're eaten in balance. Contrary to the popular idea, there has been no thorough studies showing any link between high-fat diets and heart disease. In fact, rates of heart disease in Americans have gone up, even as fats as a percentage of calories in the average American diet have gone down. Neither does fat make us fat; otherwise, as a nation, we'd be skinnier now than ever. Instead, the rates of obesity have soared. Fat is calorie-dense compared to carbs or proteins (9 calories per gram of fat, compared to 4 calories per gram of protein or carb), but don't let this scare you. Fats actually trigger the body to feel full, and can help prevent overeating.

Proteins, or more precisely the amino acids that make up proteins, are the literal building blocks of our bodies. The protein we eat is divided during digestion into amino acids, which are formed again into our body's own proteins and go on to build the cells that make up our body. There are eight essential amino acids our bodies must get from food, and several more children and some adults may need. Meat and dairy contain all of these, and are known as "complete protein." But all the essential amino acids can be gained from vegetable sources, too; it just takes a little more variety. Vegetarians can get all the proteins they need by eating beans, grains, and for some, eggs and dairy. Like fats, proteins can help make you feel full. There's some evidence that protein interferes with the absorption of calcium, potentially leading to osteoporosis. This may explain why countries who eat the least amount of dairy most often have the lowest rates of osteoporosis. There's no proof, yet. Extremely high levels of protein can cause kidney damage and other problems, but this is normally only a problem for athletes who consume protein drinks and other supplements.

Carbohydrates have been the star of the macronutrients since the late 1970's, with a prized place on the bottom of the food pyramid. But the results may in fact be the so-called obesity epidemic! As we cut fats out of our diets, we replaced them with carbs, especially cheap, processed carbs. A classic example is the American breakfast, which nationally went from being eggs and meat to breakfast cereal and juice. We also consume much more white breads, pastas and rice, soft drinks, sports drinks and other sugary drinks, not to mention donuts, bagels, cookies and candy. Carbs have two major points against them. First, carbs are essential for the body to store fat. Without carbs, no fat storage occurs. Second, carbs make us feel hungry. By stimulating insulin production, carbohydrates drop blood sugar and trigger hunger. It's easy to come away from a meal of primarily carbohydrates feeling more hungry than when you started! But carbohydrates are not inherently bad. Like proteins and fats, they are essential to our bodies. Some authors have divided carbs into "good carbs" and "bad carbs." Bad carbs, or simple carbohydrates, are digested very quickly, resulting in a spike of insulin and hunger. Good carbs, or complex carbohydrates, include fiber and digest slowly. No insulin spike, less hunger.

The truth is, there are no "good guys" and "bad guys" in the world of macronutrients. Fats, proteins and carbohydrates are all necessary parts of our diets. What's important is how we eat them, and in what proportions. By placing more emphasis on one macronutrient over another, low-fat diets and low-carb diets both cause imbalances in the diet and in the body. Because of the call from nutritionists, scientists and the government to eat less fat, Americans have been eating more carbs, and packing on the pounds.

Importantly, these macronutrients are far from the only nutrients we need. We also need vitamins, minerals, and dozens if not hundreds of micronutrients. If you're looking for advice on what to eat, here it is: ignore the macronutrients, and the micronutrients, and focus on eating whole, real foods. Whole foods provide these nutrients -- macro and micro alike -- in combinations and proportions our bodies need. Obesity, heart disease, type 2 diabetes and cancer in this country rose when we started taking the nutrients out of foods, and the foods farther and farther out of nature. By putting whole foods back in our diets, we'll eat less of all the "bad" things -- simple carbs, trans fats -- and more of all the nutrients our bodies need, in the ways our bodies need them.