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High
Carb Diet Best in
Combination with Exercise
Excerpt By Merritt McKinney, Reuters
Health
NEW
YORK (Reuters Health) - Low-fat diets that are high in carbohydrates
lower levels of harmful cholesterol, but they also can raise levels
of other blood fats linked to heart disease. However, moderate
exercise seems to counteract most of the potentially harmful effects
of a high-carb diet, researchers in the UK report.
Low-fat diets
are usually recommended because they reduce the risk of heart
disease by lowering levels of LDL (''bad'') cholesterol, Dr. Adrianne
E. Hardman of Loughborough University in Leicestershire, told
Reuters Health.
Since foods
that are low in fat tend to be rich in carbohydrates, low-fat
diets are usually high-carbohydrate diets, noted Hardman, the
lead researcher on the new study.
Such high-carbohydrate
diets, she said, have been shown to increase blood fats called
triglycerides, which are thought to raise the risk of heart disease.
They can also lower levels of the ``good'' cholesterol HDL, Hardman
added.
``Theoretically
at least, these changes might offset any benefits for heart disease
risk accruing from the decrease in LDL cholesterol,'' she said.
But in a study
appearing in Arteriosclerosis, Thrombosis, and Vascular Biology:
Journal of the American Heart Association, Hardman and her colleagues
found that moderate exercise prevents the potential harmful effects
of a high-carbohydrate diet.
``Our study
shows that moderate exercise--brisk walking for most middle-aged
and older people--negates at least some of the potentially negative
effects of a high-carbohydrate diet,'' Hardman said.
``We studied
people's responses to ordinary meals and found that, when they
were doing daily exercise the increase in their blood triglycerides
which was seen when they ate a low-fat, high-carbohydrate diet
was entirely prevented,'' she explained.
The study
included eight women in their 50s or 60s who went on a series
of 3-day diets: a low-carbohydrate diet, a high-carbohydrate diet
without exercise, and a high-carbohydrate diet combined with an
hour of brisk walking each day. At the end of each diet, the women
ate a high-fat meal and then had their triglycerides measured.
As expected,
triglyceride levels were higher after the high-carbohydrate diet
without exercise than after the low-carbohydrate diet. But the
increase in triglycerides was significantly lower after the high-carbohydrate
diet plus exercise than after the high-carbohydrate diet without
exercise.
However, exercise
did not improve the decrease in HDL cholesterol that occurred
after the high-carbohydrate diet.
Still, Hardman
said ``there is no need to be concerned that low-fat, high-carbohydrate
diets may have some negative effects on the levels of blood fats,
provided that people engage in regular, frequent exercise.''
She noted
that moderate-intensity exercise appears to be sufficient to counteract
the negative effects of high-carbohydrate diets.
In fact, according
to Hardman, this diet and exercise combo ''may be the best of
both worlds for coronary heart disease risk.''
SOURCE:
Arteriosclerosis, Thrombosis, and Vascular Biology 2001;21:1520-
Reference
Source 89
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