Low-carbohydrate and so-called Mediterranean diets may be more
effective
than low-fat diets, according to a major new study published in
Thursday's
New England Journal of Medicine.
Researchers studied 322 moderately obese employees of a research
center in
Israel, randomly assigning them to three diet groups and providing
them
with encouragement and instruction over a two-year period.
Members of the low-fat group lost an average of 6.4 pounds,
while those in
the low-carb and Mediterranean groups lost about 10, said Dr. Meir
Stampfer, nutrition professor at the Harvard School of Public
Health and
the paper's senior author.
While there has been concern that low-carb diets can be harmful
to
cardiovascular health, Stampfer said that the participants who
followed the
low-carb and Mediterranean diets actually had better cardiovascular
health
than those in the low-fat group. For people with cholesterol
problems, the
low-carb diet seemed best; for those at risk for diabetes, the
Mediterranean diet provided more health benefits.
"The take-home message should be that we should abandon the
idea that
low-fat diets are the number one way for people to lose weight,"
he said.
"It wasn't the best diet. It can be helpful for some people, but
overall I
think the first choice should be the Mediterranean or the low
carb."
Study participants generally ate lunch at the same cafeteria,
where foods
were color-coded with stickers to correspond to the different
diets; they
also met with dietitians periodically over the two years. People in
the
low-fat group were advised to eat low-fat grains, vegetables,
fruits, and
legumes and were told to avoid sweets. In the low-carb group,
participants
were advised to choose vegetarian sources of fat and protein and to
limit
carbohydrate intake. Those on the Mediterranean regimen were
advised to eat
a diet high in fish and poultry, as well as olive oil and nuts.
Participants, 86 percent of whom were men, were encouraged to
continue the
eating patterns at home. Calories were not limited in the low-carb
group,
but in the other groups, women were expected to eat 1,500 calories
a day
and men, 1,800.
One of the study's great strengths, Stampfer said, was that
after one year,
95 percent of participants were still following the diet, and 85
percent
stayed on after 2 years. Most people have trouble sticking with
regimens
for that long.
This suggests that diets connected to the workplace may be
particularly
effective, according to Susan Roberts, a Tufts University nutrition
professor.
"Whether Americans would want this is another story of
course," she said
in an e-mail. "It seems fairly invasive to have overweight people
in your
company selected out for dietary instruction and monthly
weigh-ins."
Business groups agree that workplace diets pose ethical
problems. "We
would never ever say we're putting our employees on a diet," said
LuAnn
Heinen, vice president of the nonprofit National Business Group on
Health.
"But companies have really connected the dots: We're paying for
healthcare
costs, our employees are paying for healthcare costs, and we're
serving
them Krispy Kremes every morning."
Instead of diets, she said, businesses are now taking steps to
write
caloric limits or nutritional guidelines into their contracts with
food
service providers.
Roberts said it's not clear from the research whether an
individual,
dieting without the workplace support provided by the study, would
have the
same success.
c.2008 The Boston Globe