By Linda
Carroll
MSNBC
CONTRIBUTOR
PHILADELPHIA, Oct. 22 —
For years diet doctors have criticized Americans for yo-yo dieting. But
looking at the protein advice given by nutrition specialists over the past year
or two, it seems instead that it’s the experts who’ve been bouncing back and
forth with no clear advice for confused consumers.
AT ONE TIME or another,
protein, carbohydrates and fats have all been vilified. These days, when you sit
down to a meal it seems as if you’re facing a traitor in every bite.
A prime example of recommendation flip-flopping is the experts’ advice on
protein. Back in the 1960s, Americans were told they would be healthy if they
ate lots of meat. But over the next two decades, health experts began to promote
high-carbohydrate diets and to warn Americans against eating too much protein.
When the low-carbohydrate, high-protein Atkins’ diet first came out 30
years ago, and again after its recent resurgence in popularity, mainstream
experts came out strongly against it: protein — along with fat — is what is
killing Americans, they intoned.
In fact, in 2000, the American Heart Association published several
statements critiquing the regimen. The association insisted that there was no
evidence showing that high-protein meals could lead to weight loss and they
might even hurt the dieter’s kidneys and rob strength from the bones.
A year later, the heart
association backed off these statements a bit and simply argued that weight loss
seen by those following the protein gurus was simply “fluid loss.” And still
they warned against deviations from the USDA’s Food Pyramid.
NEW PROTEIN RANGES
But the tide seems to be turning yet again.
The latest nutrition guidelines seem to reflect confusion even among the
experts. No longer are there hard and fast numbers for the percentages of major
food groups. Now protein can range from 10 percent to 35 percent of daily
intake. At the annual meeting of the American Dietetic Association this week,
nutritionists basically admitted that they really don’t know how much protein
Americans need.
And several new studies have shown that diets that have moderately high
levels of protein can lead to weight loss that targets fat and spares muscle,
said Donald Layman, a professor in the department of food science and human
nutrition at the University of Illinois, Urbana-Champaign.
While all low-calorie diets
lead to weight loss, recent research has shown that not all calories are created
equal, Layman said at the meeting. For example, one new study looked at two
groups of dieters: one with a high-protein regimen — 125 grams of protein and
171 grams of carbs — and one with a high-carbohydrate regimen — 68 grams of
protein and 246 grams of carbs. Both groups were also required to exercise.
At the end of four months, people who ate more protein lost more weight —
22 pounds versus 15 pounds. Further, people on the high-protein diet had lost
more fat and less muscle than the group on the high-carb diet.
Another important finding: higher levels of protein may also help dieters
stick with their plans.
Studies have shown that protein, more than carbohydrates or fat, leads to
feelings of fullness and satiety, said Richard Mattes, a professor of foods and
nutrition at Purdue University. People given a high-protein breakfast feel full
longer than those who eat a carbohydrate-rich breakfast, Mattes said.
Mattes also cautioned that the form of protein consumed makes a
difference. Solid protein is satisfying. Protein in liquid form is not.
DIETING RECOMMENDATIONS
Ultimately, the percentage of protein you need will depend on whether you
are dieting or not, said Cathy Nonas, of the New York Obesity Research Center in
New York City. “If you’re on a 1,200 calorie a day diet and want to lose weight
and you’re only eating 10 percent protein, you’re not getting enough protein to
support lean tissue. Even 20 percent isn’t enough to support lean tissue.
Studies have shown that you need to get at least 76 grams of protein, so that
means you have to go to the upper ranges of the protein recommendations for a
1,200 calorie diet.”
But Nonas and the other
experts stopped short of recommending the very high levels of protein suggested
by eating plans like the Atkins’ diet because these plans so drastically cut
carbohydrates — the initial phase of the Atkins’ diet limits carbohydrates to 20
grams a day.
That’s because carbohydrates are the major source of fiber in the diet.
Just cutting carbohydrates back to 50 percent of your diet would be
enough, Nonas said, and that would still allow for enough carbs to be within the
range recommended by the ADA.
“You can increase lean protein and decrease carbohydrates and still have
a really healthy mix,” she said.
Linda Carroll is a freelance reporter based in
New Jersey. Her work has appeared in The New York Times, Health and Smart Money.
