Lately there has been much publicity describing the merits of a low-carbohydrate, high-protein diet. This publicity, though, should be taken with a grain of salt - and a slice of bread.
Diets such as Barry Sears' "The Zone" and Robert Atkins' "New Diet Revolution" - with Atkins' the more extreme of the two - point at carbohydrates as the source of America's obesity problem. But nutritionists at the University believe they are ill-advised programs.
Even though carbohydrates from vegetables and fruits provide vital macronutrients, these diet doctors have spread anti-carbohydrate nutritional information across the nation, and in the process, have fooled much of America.
The new diets differ from the food pyramid-centered conventional diet in which carbohydrates are the central part of a healthy diet.
Sears' Zone diet, known widely for its 40/30/30 carbohydrate/protein/fat ratio, focuses on keeping low blood insulin levels by limiting carbohydrate intake. Sears' theory claims that increased insulin levels in the bloodstream can interfere with the body's ability to burn fat because insulin levels rise in response to consumption of quick-energy carbohydrates and cause the body to store sugar as fat.
Cutting out carbohydrates and replacing them with protein and fat will decrease the insulin response, Sears says, so theoretically the body is being stimulated into burning stored fat.
Jennifer Lucas, a clinical nutritionist at the University Medical Center, disagrees with Sears' theory.
"Eating carbohydrates raises insulin. But so does an increase in protein. So it's really not as simple as dealing with carbohydrate consumption and fat storage," Lucas said.
She said the human brain runs on glucose and that since glucose comes from carbohydrates, it hints at the dieter's sluggishness.
Sears says eating three grams of protein for every four grams of carbohydrates keeps the blood hormone levels in a healthy balance. But even so, no scientific evidence exists to prove Sears' theory.
Laura Knotts, a registered dietician at the University Heart Center, said "It's not something we recommend. The people on the diet don't necessarily think of health considerations. They mainly try it for cosmetic reasons."
Atkins' "New Diet Revolution," the more extreme of the two diets, advocates the lowest carbohydrate intake of any recent diet. Proteins and fat take the place of carbohydrates, as he encourages virtually unlimited portions of meats, which are high in protein, and often in saturated fat.
Atkins' diet is based on the body's natural response to the lack of carbohydrates. When the body is not taking in adequate amounts of carbohydrates, it burns off stored fat. This state produces an increase in blood ketones - compounds resulting from fatty-acid breakdown which suppress hunger and result in a decreased calorie intake.
Although a decreased appetite may account for some of the weight loss found with high-protein diets, much is actually due to water loss normally stored in tandem with carbohydrate in muscles. Lucas believes the diet does not bring any significant weight loss.
"When you want to lose weight, you don't just want water loss. You want to lose actual fat," Lucas said.
By following any of the carbohydrate-limiting diets, the body also misses out on many dietary components such as fiber, vitamins and minerals.
Atkins acknowledges that deficiencies may arise when following his diet and therefore recommends taking vitamin supplements. Supplements, however, do not provide fiber or cancer-preventing chemicals normally found in vegetables and fruits.
"The Atkins diet says 'no milk, fruit, bread, pasta and rice.' Most times they have excluded foods for no reason at all," Lucas said.
Dietary fiber is an important component of any healthy diet that prevents many health problems and may assist in weight management. It exists in two forms - soluble and insoluble. Insoluble fiber, found in bran, cereals and vegetables, has been found to be helpful in the prevention or treatment of constipation and colon cancer. Increased fiber intake is also correlated with improved control of diabetes.
Soluble fiber - of which the average American does not get enough - has a positive effect on blood cholesterol levels.
The high protein, low carbohydrate diets are heart-unhealthy in a few ways. Low intake of dietary fiber, coupled with an increased consumption of meats that are often higher in saturated fat and cholesterol, have a detrimental effect on heart health.
"We do know that the high saturated fat leads to heart disease. We don't know if the Atkins diet necessarily leads to heart disease. But we do know that his diet is high on saturated fat and that previous studies have shown those diets lead to heart disease," Lucas said.
But for all the talk about negative effects of the diets, they contain some nutritionally-sound advice.
The diet offered in "The Zone" suggests lowering caloric intake by limiting simple carbohydrates like regular sodas, snack foods and refined grains. They also advocate reducing intake of fat-free high carbohydrate snacks and desserts and increasing consumption of water.
Lucas says Atkins' idea of making dieters follow a strict regimen will make the diet hard to follow.
"People on these diets have a very difficult time. A diet shouldn't be about what's legal and illegal to eat. It should be about balance," Lucas said.
In light of the recent diet crazes, no revolutionary changes have been made in general dietary recommendations. The nutritionists at the University Department of Nutrition Services suggest a diet with plenty of grain products, fruits and vegetables, limited fats, saturated fats and cholesterol, and moderate sugar and sodium. By eating a variety of foods in moderation and including exercise as a part of a daily routine, one can lead a long healthy life.
Both Lucas and Knotts say that people may not consider the possible adverse effects that these diets can create in the long run. Nutritional data points to a connection between low carbohydrate and increased saturated fat diets and an increased risk of heart disease and cancer.
"It's attractive to people. We tend to like high carbohydrate foods. People don't want to hear about balance," Knotts said.
Diet crazes develop every few years as people search for quick ways to lose weight and often are based on less than scientifically accurate theories.
Past crazes have included the low fat diet of the late 80s and early 90s, and in the 70s, a diet similar to Atkin's low-carbohydrate regimen.
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