©2002 WGBH Educational Foundation.
Standards of beauty have changed over the years. In the late 1800s,advertisers regularly used models who would be considered overweightby today's standards. Times have changed dramatically. Most Americansare exposed to thousands of media messages every day -- in magazinesand newspapers, on television, on outdoor billboards, and over theInternet. These messages promote bodies that are thin and, in some cases,unrealistically proportioned, and they are creating a culture of youngpeople who are obsessed with losing weight.
As a result ofthis obsession, many people have sworn off fat. They avoid eating fat inany form and, instead, obtain most of their calories from carbohydrates,like bread and pasta. For decades, doctors and health experts supportedthis fat-free nutritional strategy. Fat was the enemy, they said; it wasthe cause of obesity and heart disease. Carbohydrates were your friendsand could be consumed, many thought, in mass quantities with few concernsabout health consequences. Recent studies, however, have begun to revealthe flaws in this thinking.
A nutritional plan that shuns fatignores this food's important role in the body. While fat's main purposeis to store energy, it serves many other functions as well. Either in itswhole form or broken down into small molecules, fat does the following:provides insulation, builds membranes, aids digestion, promotes propernervous system function, regulates hormones, keeps the skin healthy,and aids the chemical communication between cells. And these are justa few of the important things that fat does for us. Still, many peoplecontinue on a fat-free path.
Somewhat surprisingly, fat-freediets often result in the accumulation of excess body fat. Carbohydrates,including sugars and starchy foods, provide the body's most efficientform of energy. They are broken down quickly into glucose, the sugar thatcells need in order to function. This is why energy bars used by athletesare made up primarily of carbohydrates: They are quickly broken down inthe stomach, and the resulting sugars are easily transported throughoutthe body via the bloodstream.
When the body is active at highintensity for long periods of time, carbohydrates must be eaten regularlyto provide the cells with the energy they need. Carbohydrates that areconsumed when the body is at rest, however, are stored. Relatively smallamounts of carbohydrates can be stored in the muscles and the liver as acomplex sugar called glycogen. When glycogen stores are full, however,and there is no further demand for sugar, carbohydrates are stored asfat.
Although most doctors and nutritionists still recommendthat people get the majority of their calories from carbohydrates,they also suggest that many people would benefit from increasing theirfat intake. According to most nutritionists, the ratio of carbohydrate,fat, and protein calories should, in fact, be much closer to equal --at 40, 30, and 30 percent respectively. They stress that exercisingand eating moderately from all of the food groups is the proper path tobetter health.