July 16, 2008 -- The debate about the best weight
loss diet is on again, with all the usual contenders.
A low-fat diet is not the only safe and effective way to shed pounds,
according to a new study that shows low-carbohydrate and Mediterranean diets
also result in weight
loss, and appear to also offer other health benefits.
"We saw a reduction in weight in all three diets," says Iris Shai,
RD, PhD, the study's lead author and a researcher in nutrition and chronic
diseases at Ben-Gurion University of the Negev, Beer-Sheva, Israel. "But we
saw that other diet strategies, which are higher in fat proportions, like the
Mediterranean diet, and the low-carb diet, even result in an increase in weight
loss and improvement in blood lipids and blood glucose measurements."
Mediterranean and low-carb diets may be effective alternative diets to the
low-fat plan, the researchers conclude. "There are some other diet
strategies out there," Shai says.
The study is published in The New England Journal of Medicine.
Comparing Low-Fat, Low-Carb, and Mediterranean Diets
Shai and researchers from Harvard University and other institutions assigned
322 moderately obese men and women, average age 52 and with a body
mass index (BMI) of 31, to one of three diets.
The low-fat diet was based on American Heart Association guidelines. In the
group following this diet, women ate 1,500 calories a day and men ate 1,800
calories. They took in just 30% of calories from fat, including 10% saturated
fat, and were limited to 300 milligrams of cholesterol a day. (A large egg has about 200 milligrams
of cholesterol). They focused on eating low-fat grains, vegetables, legumes,
and fruits -- and reduced intake of extra fats, sweets, and fatty snacks.
The Mediterranean diet was based on the writings of Walter Willett from
Harvard Medical School. In the group following this diet, women consumed 1,500
calories a day and men consumed 1,800 calories. The goal was to eat no more
than 35% of calories from fat, and the main sources of added fat were olive oil
and a few nuts a day. The diet was rich in vegetables and low in red meat, with
fish and chicken replacing beef and lamb.
The low-carb diet was based on the Atkins plan. In this group, calories weren't
restricted. These participants were told to eat about 20 grams of carbs a day
(about the amount in two slices of bread) for two months, and then increase it
to no more than 120 grams a day. They focused on vegetarian sources of fat and
protein and avoided foods with trans fat.
Study participants were from a workplace in Dimona, Israel, and ate their
lunch, typically the big meal of the day in Israel, in the company cafeteria.
Cooks at the company made sure the subjects had the food items they needed.
Participants were weighed in every month and had other measurements, such as
cholesterol and blood sugar taken four times during the two-year study, from
2005 to 2007.
The maximum weight loss occurred during the first six months; then dieters
went on maintenance.