http://www.cnn.com/2009/HEALTH/02/25/best.diet/index.html

Low-fat? Low-carbs? Answering best diet question

Story Highlights

* Researchers test four diets for weight-loss effectiveness

* Dieting theories emphasize carbohydrates, proteins or fats

* No huge differences seen between diets, key is calorie reduction

By Madison Park
CNN

(CNN) -- The dieting world screams with contradictory advice: Carbs are
evil; carbs are good for you. "Good fat" is healthy; "good fat" has tons of
calories.

Researchers at the Harvard School of Public Health and the Pennington
Biomedical Research Center put four popular diets -- high carb, high fat,
low-fat and high protein -- to the test to see which of the regimens
resulted in more weight-loss success.

After two years of monitoring the participants, "all the diets were
winners," said study co-author Dr. Frank Sacks, a professor of
cardiovascular disease prevention at the Harvard School of Public Health.
"All produced weight loss and improvements in lipids, reduction in insulin.

"The key really is that it's calories. It's not the content of fat or
carbohydrates, it's just calories," said Sacks. The findings are published
in the latest edition of the New England Journal of Medicine.

For the study, 811 overweight adults in Boston, Massachusetts, and Baton
Rouge, Louisiana, were assigned to one of four diets.

A quarter went on a carbohydrate-heavy diet, some on high-fat, others on
low-fat and the remaining on high-protein diet. The four diets were not
based on popular diets, Sacks said.

Regardless of diet, most participants had dramatic weight loss after six
months, losing an average of 13 pounds.

According to Sacks' research, many of the 800-plus participants regained
weight after a year, but about 80 percent of them lost at least eight
pounds after two years. And 15 percent of the participants lost at least 10
percent of their body weight.

The study, funded by the National Heart, Lung and Blood Institute of the
National Institutes of Health, showed little difference in users' satiety,
hunger or satisfaction with their diets.

Participants could attend individual sessions where dieticians educated
them and group sessions where they discussed their experiences with one
another.

Those who had better attendance in the sessions had stronger weight-loss
results. "These findings together point to behavioral factors rather than
macronutrient metabolism as the main influences on weight loss," according
to the study. Macronutrients are the three main nutrients the body uses in
relatively large amounts: proteins, carbohydrates and fats.

"No one of those diets are necessarily better than any other diet," Sacks
said.

In an accompanying editorial in the New England Journal of Medicine,
Martijin B. Katan wrote the researchers' hypothesis is "plausible," but
said the "differences in macronutrient intake were too small."

There was an underlying similarity between the four diets.

On average, the overweight participants had a 750-calorie reduction per
day. An average-sized male who consumed 2,800 calories a day was prescribed
just over 2,000 calories and a woman who ate 2000 calories a day was
prescribed 1,250 calories.

All diets were compatible with American Heart Association guidelines, Sack
said. The study did not give the participants food. For the first 10 days,
participants received menus, then were assigned to create their own using
the healthy food options.

Depending on their prescribed diet, participants ate a wide range of
carbohydrates, fat and protein, derived from healthy foods, such as olive
oil, pasta and nut butter.

From these results, Sacks recommends going with "the diet you feel most
comfortable that is healthy, that appeals to you in terms of what foods are
in it, that isn't a drastic crash diet. Whatever allows you to keep the
calories down and not feel really deprived."

Calorie restriction can be done without feeling deprived, said Dr. Luigi
Fontana, an associate professor of medicine at the Washington University
who studies the effects of calorie restriction on longevity. But he warns
against just halving a person's current diet.

"A lot of people think of calorie restriction like eating half a hamburger,
half a pack of French fries -- that you can obtain by reducing in half your
portions," Fontana said. "That's calorie restriction with malnutrition."

Dr. Melina Jampolis, the diet and fitness expert for CNNhealth warned
against drastic measures like completely focusing on one macronutrient.
"People want to be extreme," she said. "You say cut back on sugar, they cut
it completely. The take-home would be that there is no markedly superior
diet. If there was, people wouldn't stick with it anyway."

Cindy Moore, the director of nutrition therapy at Cleveland Clinic and a
registered dietician agreed.

"People gravitate to the latest fads or trends, because they may have known
someone who was successful in losing weight. That friend may have been in
that early grace period of losing weight. The other thing is people think
they need that magic bullet."

But a significant change in eating habits -- like cutting out an entire
nutrient group like carbohydrates, proteins or fats, often can't be
sustained.

Weight loss tends to be dramatic during the first few months. Brenda
Driver, of Springfield, Missouri, was not involved in the study but says
she lost 10 pounds in 10 days on the Atkins diet by eschewing all
carbohydrates.

The 26-year-old and her fiance said they were "not looking at a crash diet,
but want to jump start weight loss." The former vegetarians began eating
meat again because of the high protein demands of the diet.

Driver said she's aware the Atkins diet is not an ideal long-term plan. Six
years ago, she tried the diet for seven months and lost 45 pounds. She
finally quit the diet because of her chocolate cravings.

This month, Driver and her fiancedecided to give the Atkins another try. "I
want to rebel against the whole,
'you're-engaged-now-you-have-to-lose-weight,' " she said. But it would be
nice to look slimmer in those wedding photos, she said.

"I'm approaching it as a temporary thing. Vegetarianism is where I want to
be the rest of my life."

Moore said the basics of losing weight boil down to this: Limit the
calories consumed so a person is taking in less than the body needs or
increase activity to burn more energy.

The problem, she said is that, "People get discouraged if weight loss is
really, really slow."