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A moderate fat diet based on the diets
of southern Europe and the Mediterranean allows for
a greater variety of foods that are considered very
appetizing compared with a strict, bland, low-fat diet.
The main dietary fats in a typical Mediterranean diet
are unsaturated. Unsaturated fat, or "healthy fat,"
has been associated with lowering cholesterol.
In the study of 101 overweight men and
women, half were instructed to eat a low fat diet (20%
calories from fat) and half to eat a moderate fat diet
(35% calories from fat, mostly monounsaturated from
peanut butter, nuts, olive and canola oils). All participants
were given guidelines to eat a diet of approximately
1,200-1,500 calories that was low in saturated fat and
cholesterol.
Only one in five study participants could
stick to the low fat diet while more than half stuck
to the moderate fat diet. Both groups lost an average
of 11 pounds in the first year. However the moderate
fat group kept a significant amount of weight off for
18 months, whereas the low fat group did not. The moderate
fat group was followed for an additional year (2 1/2
years total) and still kept a significant amount of
weight off.
"My patients loved this diet because
they could include favorite foods if they carefully
watched portion sizes," added McManus.
Study subjects substituted high saturated
fat foods, like butter, with healthy monounsaturated
fat foods, like peanut butter. They tossed nuts on their
salad instead of croutons and used small amounts of
full fat salad dressings.
Those in the moderate fat group increased
peanut butter consumption by almost a serving (2 tablespoons)
per day, increased peanut consumption by a half a serving
(1/2 ounce or a small handful) and tree nuts (almonds,
cashews, walnuts, etc.) by a half a serving over their
baseline diets. Other foods such as healthy oils (olive,
peanut and canola) and avocados were added in small
amounts. Surprisingly, those on the moderate fat diet
increased consumption of vegetables by one serving per
day. Intake of fiber was also increased significantly,
and the moderate fat group tended to eat more protein
compared to their baseline diets. In contrast, the low
fat group decreased their consumption of vegetables
and fiber compared to baseline.
"Any low calorie diet can work in
the short run, but we need to know what kind of eating
pattern can sustain long-term weight loss-which is key
to preventing chronic disease," said McManus.
"Obesity has become a major public
health problem in this country," said study co-author
Frank Sacks, MD, of HSPH and BWH. "We must find
a diet that will help American lose and keep weight
off long term."
Obesity is a chronic widespread disease
of increasing prevalence, which has become a leading
public health and clinical concern. It is now estimated
that over 50 million people, or more than 23 percent
of the adult U.S. population, are obese. Overweight
and obesity are associated with major chronic illnesses,
including hypertension, coronary artery disease, diabetes,
arthritis, and certain forms of cancer.
The study was equally supported by the
Peanut Institute, the International Olive Oil Council,
and the International Tree Nut Council.
BWH is a 716-bed nonprofit teaching affiliate
of Harvard Medical School and a founding member of Partners
HealthCare System, an integrated health care delivery
network. Internationally recognized as a leading academic
health care institution, BWH is committed to excellence
in patient care, medical research, and the training
and education of health care professionals. The hospital's
preeminence in all aspects of clinical care is coupled
with its strength in medical research. A leading recipient
of research grants from the National Institutes of Health,
BWH conducts internationally acclaimed clinical, basic
and epidemiological studies.
The Peanut Institute is a not-for-proft
organization dedicated to supporting nutrition research,
education. and the assessment of health eating patterns
throughout the human life cycle. For further information
write PMKAssoc@aol.com.
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