THURSDAY, Dec. 30, 2004 (HealthDayNews) -- People who eat fast food frequently are more likely to gain weight and develop insulin resistance, and such eating habits may increase the risk of obesity and type 2 diabetes, new research claims.
"These findings suggest that frequent fast food consumption cannot be part of a healthful diet, despite claims to the contrary by the food industry," said senior study author Dr. David Ludwig, director of the obesity program at Children's Hospital Boston.
This is the first long-term investigation to show the link between fast food, weight gain and insulin resistance; it appears in the Jan. 1 issue of the The Lancet.
Ludwig and his colleagues produced an alarming sequence of statistics to show the toll obesity is taking in the United States. About 30 percent of Americans are overweight or obese, compared to only 23 percent during the period 1988 to 1994. The prevalence of overweight rose by 50 percent in children and adolescents during the past decade, to about 15 percent of all people in that age segment. And obesity is responsible for 300,000 deaths and $100 billion in annual health-care costs, according to the researchers.
The repercussions of obesity and type 2 diabetes continue far and wide. A new study by UCLA researchers found that advanced heart failure patients with diabetes who are treated with insulin have a death rate four times higher than similar patients treated with oral medications. Between 25 percent and 44 percent of heart failure patients also have diabetes, according to the study, which appears in the January issue of the American Heart Journal.
Because the obesity epidemic has come on so rapidly, most experts point to so-called environmental factors as the root cause. One such factor could be fast food. According to The Lancet study, fast food accounts for 10 percent of total energy consumed by children, up from 2 percent in the late 1970s.
Yet very little research has been done in this area.
"There have been no large-scale, long-term studies examining the health effects of fast food, which is surprising given that this is the dominant dietary pattern among children and young adults today," said Ludwig. "In the absence of such data, the fast food industry is allowed to market their products without restriction to young children."
To try to isolate the effect of fast food on excess weight and insulin resistance, two major risk factors for type 2 diabetes, the study authors assessed the dietary habits of 3,301 black and white adults aged 18 to 30. Participants were asked to provide information about diet, physical activity and other lifestyle factors, including how often they ate breakfast, lunch or dinner at "places such as McDonald's, Burger King, Wendy's, Arby's, Pizza Hut, or Kentucky Fried Chicken."
White women ate fast food the least often: 1.3 times per week compared with about twice a week for the other groups.
Individuals who ate fast food more than twice a week gained an extra 10 pounds and had a twofold greater increase in insulin resistance than people who ate less than once a week at one of these establishments. The association was somewhat weaker in black people.
The findings point only to an association between fast food and obesity and insulin resistance, not a cause-and-effect relationship, the researchers stressed.
Nevertheless, the link seems to make sense.
"Fast food inherently contains some of the worst aspects of a wide variety of dietary factors, including large numbers of calories served in very calorie-dense servings," Ludwig said.
Caloric density, essentially the number of calories per bite, may be a key factor in this equation, Ludwig added. "Fast food is designed to promote consumption of the maximum number of calories in the minimum amount of time," he explained. "This may confuse the mechanisms we have to regulate our appetite and the intake of food."
Dr. Arne Astrup, author of an accompanying editorial in The Lancet, is head of the department of human nutrition at Royal Veterinary and Agricultural University in Copenhagen, Denmark, and medical advisor to Weight Watchers Denmark.
"The kind of foods that are served in fast food restaurants are generally high-energy density, the portion sizes have gone up dramatically and also there are a lot of soft drinks where we know the sugar seems to be more fattening than in solid foods," Astrup said. "They also lack a lot of the nutrients that we know have some protective effect against weight gain, such as high, whole-grain food products."
Moreover, Astrup said, fast food generally does not fill you up. "That's one of the things that makes it very plausible that this finding is correct," he said.
Ludwig said he hopes that demonstrating fast food has unhealthy effects will translate into changes in food industry marketing practices. "At a time when childhood obesity has become of potentially overwhelming public health significance, we have to ask ourselves whether we can continue to tolerate marketing campaigns aimed at young children."
For his part, Astrup hopes that both fast food restaurants and the people who frequent them will think a little more about what's in those foods.
"I think it's a good message to start to look at alternatives," Astrup said. "Personally, if I want to have some fast food, I go for Japanese sushi or maybe Thai food where I know they produce it in a genuine way without adding a lot to it. There are ways to have fast food but not necessarily that will make you fat."
Responding to the report, Dr. Cathy Kapica, global director of nutrition for McDonald's, said, "It is not where you eat, but the food choices you make, and especially how much you eat. At McDonald's, we continue to demonstrate our commitment to helping our customers achieve balanced, active lifestyles by offering even more quality food choices, in a variety of portion sizes, that can easily fit into a variety of eating styles."
The National Restaurant Association said it was unable to respond to the specifics of the study without looking at the methodologies.
But the group said in a statement, "At face value, the findings seem to support what we have maintained for some time. Healthful living is accomplished through various lifestyle choices -- particularly balance, moderation, physical activity, and personal responsibility. Dietary experts agree that all foods can be
part of a healthy diet -- foods that are readily available in varying
portion sizes on all types of restaurant menus."
More information
Visit the National Institutes of Health for more on childhood obesity.
