Fad diets: good or bad?
Tuesday, May 31, 2005
MANHATTAN, Kan. - Quick weight loss programs, also known as fad diets, seem to be losing more credibility every day, said Denis Medeiros, head of the department of human nutrition at Kansas State University.
Regardless of being healthy, people want to lose weight and look great. For that reason, they search for quick weight loss diets, said Medeiros, who was speaking at a meeting of the Master Food Volunteers May 25. Some of the most popular such diets are the Atkins, South Beach, Scarsdale, Zone, Metabolism, Grapefruit and Cabbage Soup diets.
According to Medeiros, being categorized as having an ideal weight may not mean that someone is healthy.
"Overweight and obese people who have some physical activity are healthier than those who are not overweight but are not physically active," Medeiros said. "Physical fitness is best and can outweigh the body mass index (BMI) numbers that are given to categorize people as ideal, overweight, or obese."
Being overweight or obese, however, increases the risk of heart disease, cancers, diabetes, bone and joint problems and surgical risks, he said. Losing a few pounds can improve a person's health and can lower blood pressure dramatically.
An ideal BMI is 20 to 25, overweight is 25 to 29.9, obesity class II is 30 to 40 and obesity class III is more than 40. To calculate BMI, take weight in kilograms divided by height in meters squared, or pounds divided by inches squared, then multiply that answer by 705.
Medeiros recommends that men and women in obesity class III consider surgical options if they have tried to lose weight, but can not.
The Atkins diet is a popular low carbohydrate diet. It has prompted health concerns because it is high in fat, but clinical trials have not shown that people on the Atkins diet develop risk factors for heart disease, he said.
In the short term, the Atkins diet can result in more weight loss than some other diets, but most individuals fail to stay on the diet, the nutrition educator said. This is also true of conventional diets. The Atkins diet restricts fruits and vegetables, but does allow for some. It also restricts whole grains, which have health benefits.
"On the other hand, the South Beach diet may have more credibility except for the rapid weight loss in phase I which lasts two weeks," Medeiros said. "Eight to 13 pounds is claimed to be lost during this phase, which is unhealthy."
Phase II and III of the diet are relatively healthy however, because only one to two pounds are lost per week, Medeiros said. It is not as restrictive in fruits and vegetables, and it does allow for the re-introduction of foods slowly during the maintenance phase.
"Because of these fad diets, we are very good at losing weight in the United States, but we do not know how to keep it off," Medeiros said.
The problem with the two-week Scarsdale diet, is that it only allows for 1,000 calories per day, which is way too few, and according to Medeiros, can be damaging to the body.
"The Scarsdale diet can be damaging to the kidneys if there is not enough water consumed in the process," he said. "The body begins to use protein for energy and results in a high amount of nitrogen that the kidneys must get rid of, so without a lot of water, that can be damaging to the body."
According to Medeiros, the Metabolism, Grapefruit, Zone and Cabbage Soup diets all provide weight loss too quickly, or are not based on scientific reasoning. Weight loss on these diets is probably due to the low amount of calories consumed, Medeiros said.
For those who are serious about losing weight and keeping it off, he suggested reducing portion sizes, exercising and following the U.S. Department of Agriculture's Food Guide Pyramid. Small lifestyle changes can have bigger payoffs in the long run.