Too much fast food and too little exercise can have an adverse impact on the liver. Researchers in Sweden studied 18, 12 men and six women, slim, healthy adult volunteers who restricted their levels of physical activity to no more than 5,000 steps a day and ate at least two fast food meals every day for four weeks. They showed clear signs of liver damage, and also put on weight. Another group of volunteers, who were matched to members of the first group by age and sex, maintained a normal diet and did not develop signs of liver damage or gain weight. The study was designed to see what impact doubling the number of calories eaten daily and increasing body weight by 10 and 15 per cent would have on liver health. At the end of the four weeks, the fast food eaters had put on an average of 6.5 kg (14.3 pounds). Five increased their weight by 15 per cent and one person put on an extra 12 kg (26.4 pounds) in just two weeks. Moreover, after just one week on the fast food diet, blood tests showed sharp increases in a liver enzyme called alanine aminotransferase (ALT). ALT levels more than quadrupled over the four-week study period. Doctors often use increases in ALT and other liver enzymes to diagnose liver disease before symptoms develop. In 11 fast food dieters, ALT rose to levels suggestive of liver damage. Too much fat in the liver is another sign of damage. Only one fast food eater developed fatty liver, but test results from the other participants showed a steep rise in fat content in their liver cells, which is associated with insulin resistance, a precursor to diabetes. None of these changes were seen among the comparison group who maintained their normal diet. The findings showed a link between increase in ALT and weight gain and higher sugar and carbohydrate intake. Thus, while examining patients with elevated ALT, the medical history should include not only questions about alcohol intake but also explore whether or not there has been an excessive intake of fast food in the recent past.
Gut,
February 2008