Feb. 14, 2008 -- "Welcome to Fast Foods! How can we destroy your internal organs?"
It's not very catchy, but fast food restaurants may as well update their greetings, considering the negative effects their food can have on our health, our hearts and, now, our livers.
In a new study, 18 slim, healthy Swedish men and women took on a fast food diet, eating meals from popular chains twice a day for four weeks while refraining from exercise.
At the end of the experiment, blood tests showed evidence that the subjects eating fast food had liver damage. They also had gained an average of 16 pounds.
The subjects were eating "an outrageously high amount" of calories, said Keith-Thomas Ayoob, associate professor of pediatrics at the Albert Einstein College of Medicine in New York. Ayoob said the calorie intake was almost double the average daily caloric intake of most Americans, which is about 2,700 calories.
Studies have shown that a diet high in fat and calories — the magic recipe for delicious, greasy fast food — puts people at greater risk for obesity and type 2 diabetes, both of which can lead to cardiovascular diseases and heart failure.
But the Swedish study, the goal of which was to double calorie intake and increase body weight by about 15 percent, showed that the liver is also at risk when you roll up to the drive-through window.
A Super-Sized Problem
"The extra fat is the big enchilada here, the equivalent of about three sticks of butter daily," Ayoob said. "The liver is basically using its compensatory mechanism to accommodate all this extra stuff."
The liver processes fats in the blood. Excessive calories and fats overload the organ, causing fat to build up in the liver cells and leading to liver damage.
The study echoes another experiment that received both attention and an Academy Award nomination. In the 2004 documentary Super Size Me, filmmaker Morgan Spurlock followed a strict fast food diet for 30 days, eating only items from McDonald's. He consumed an average of 5,000 calories each day, equivalent to about nine hamburgers, and gained 24.5 pounds.
Though the Swedish study's participants only ate two fast food meals a day, their physical condition mirrors Spurlock's drastic physical metamorphosis. One participant gained 26.5 pounds in four weeks, two more than Spurlock had gained.
Plus, the blood tests that showed liver damage signalled a "significant risk of developing end-stage liver disease and a lower chance of survival mainly because of cardiovascular disease," according to Dr. Fredrik H. Nystrom, the primary investigator.
Back to Normal
It took Spurlock a little over a year to return to his normal healthy condition, but the liver is resilient and can recover from a four-week calorie binge, according to Ayoob.
"The liver can regenerate itself if things are caught in time," he said. "But if you've eaten like this for several years, you may have some arterial plaque buildup that would be hard to reverse."
Dr. Christine Ballantyne, medical director of the Center for Cardiovascular Disease Prevention at the Methodist DeBakey Heart Center in Houston, confirms that liver function is sensitive to dietary changes and similar damage can occur over the long term.
"People who eat fast food for longer periods of time and gain weight slower have similar bad effects," Ballantyne said.
Despite the move to add healthier items to their menus, regular meals at the local fast food joint can be as bad, if not worse, for the liver than drinking alcohol.
"It takes about 10 years to create a real, hardcore alcoholic," Ayoob said. "Ten years of eating 5,753 calories a day,and you may have a heart attack and assorted other chronic diseases because you just can't move."