Today, we know
that a high-fat diet, consumed long term, can lead to problems such as
obesity, heart disease, diabetes, and a decline in cognitive ability,
to name a few. But a recent study by researchers at Oxford University
shows it may only take a few days for fat-laden food to begin wreaking
havoc on our health.
To learn more about the short-term
effects of a high-fat diet, the researchers conducted an extensive
experiment with 32 rats. The rodents were fed a low-fat diet, comprised
of 7.5 percent fat, for two months as they trained to complete a
challenging maze and to run on a treadmill. The maze consisted of eight
different paths with a sweetened condensed milk treat at the end. The
goal was for the rats to find the treat without re-entering a corridor
where they had already been. Once all the rats had mastered the maze,
it was wiped down with alcohol, forcing them to rely on memory rather
than their sense of smell.
Then half the rats were switched to
a high-fat diet comprised of 55 percent fat, while the remainder was
left on their low-fat diet. When retested on the fifth day after the
diet switch, the rats eating fatty feed were already running 30 percent
less on the treadmill than their counterparts, and by the ninth day
were running 50 percent less. The rats on the high-fat diet were also
taking longer to complete the maze and making more mistakes during the
process. “We expected to see changes, but maybe not so dramatic and not
in such a short space of time,” said lead author Andrew Murray, a
lecturer in physiology at Cambridge University in Britain. “It was
really striking how quickly these effects happened.”
The
researchers found increased levels of a protein called uncoupling
protein 3 in the muscle cells of the fat-laden rats. This protein makes
the cells less efficient at using oxygen to make the energy required
for exercising, causing the heart to work harder and increase in size,
which may explain their reduced treadmill performance. A possible
explanation for the short-term decline in cognitive function is that
fatty foods can trigger insulin resistance, which means the body
becomes less efficient at using glucose, or blood sugar, which is
important to brain function.
Dr. Gerald Weissmann, editor of the
Federation of the American Societies for Experimental Biology, who
published the study, described the effect as “nothing short of a
high-fat hangover,” noting that “a long weekend spent eating hotdogs,
French fries, and pizza in Orlando might be a great treat for our taste
buds, but they might send our muscles and brains out to lunch.”
The
researchers have also performed similar studies of high-fat diets in
healthy young men who then completed exercise and cognitive tests. Dr.
Murray said he is still reviewing the data, but the short-term effects
of a fatty diet on humans appear to be similar to those found in the
rat experiment. “We hope that the findings of our study will help
people to think seriously about reducing the fat content of their daily
food intake to the immediate benefit of their general health,
well-being and alertness,” he said.
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