A study published in the journal Gut reports that
too much fast food and too little exercise can harm the liver.
Swedish researchers selected 18 thin, healthy volunteers - 12 men and 6
women - to attempt a 5 to 15% body weight increase by eating at least
two fast-food-based meals per day for four weeks. The participants in
this intervention group also restricted their level of physical
activity to no more than 5000 daily steps. A comparison group, matched
for age and sex, ate a normal diet and maintained normal
exercise levels.
The study authors desired to see if doubling calorific intake and
increasing total body weight had any impact on participant's liver
health. Researchers checked liver enzyme and fat levels by analyzing
blood samples both before the "fast-food challenge" began and
at regular intervals throughout the four-week study period.
Changes in enzymes, such as alanine aminotransferase (ALT), and in
hepatic triglyceride content (HTGC) were used to indicate liver damage.
Abnormally high ALT levels are frequently seen in people who consume a
lot of alcohol or who have been infected with the hepatitis C virus.
HTGC measures fatty acid levels in the liver; too much fat in the liver
leads to a condition called fatty liver disease.
At the end of the four weeks, the researchers reported:
Fast-food consumers had put on an average of 6.5 kg (14.3
lbs.)
Five participants increased their weight by 15%
One person gained 12 kg (26.4 lbs.) in two weeks
Sharp increases in ALT occurred after just one week on the
fast food diet
The average ALT level increased four-fold from 22 U/l to
of 97 U/l over the 4 weeks
ALT rose to liver damage levels in 11 participants
No changes were seen in levels in the comparison group
The increases in ALT levels were linked to weight gain and increased
sugar and carbohydrate intake. One subject developed fatty liver
disease, and there was a large rise in liver cell fat content in the
other participants.
The authors note that an increase in the fat content of liver cells is
associated with insulin resistance, which in turn is associated with
the metabolic syndrome. Insulin resistance syndrome is a collection of
biochemical abnormalities which are linked to an increased risk of
diabetes and cardiovascular disease.
Fast-food-based hyper-alimentation can induce rapid and
profound elevation of serum alanine aminotransferase in healthy subjects
Stergios Kechagias, Åsa Ernersson, Olof Dahlqvist, Peter Lundberg,
Torbjörn Lindström, and Fredrik H Nystrom
Gut. (2008)
doi:10.1136/gut.2007.131797
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: Peter M Crosta