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Some individuals may be confused or misled about
important dietary issues based on the following inaccurate claims:
1. “High-protein diets cause dramatic weight
loss.”
The weight loss typically occurring with high-protein diets—approximately
11-16 pounds over the course of a year5,6—is not
significantly different from that seen with other weight-reduction
regimens or with low-fat, vegetarian eating patterns.
2. “Fatty foods must not be fattening, because
fat intake fell during the 1980s, just as America's obesity epidemic
began.”
Some news stories have encouraged the public to discount health
warnings about the amount of fat (especially saturated fat) in the
diet, suggesting that fat intake declined during the 1980s, an era
during which obesity became more common. However, food surveys from
the National Center for Health Statistics from 1980 to 1991 show
that daily per capita fat intake did not drop during that period.
For adults, fat intake averaged 81 grams in 1980 and was essentially
unchanged in 1991. While the American public added sodas and other
non-fat foods to the diet, forcing the percentage of calories from
fat to decline slightly, the actual amount of fat in the American
diet did not drop at all. What did change was portion size. A report
in the Journal of the American Medical Association confirmed
that meal sizes have steadily risen over recent decades.28
A notable contributor to fat and calorie intake in recent years
is cheese consumption. Per capita cheese consumption rose from 15
pounds in 1975 to more than 30 pounds in 1999. Typical cheeses derive
approximately 70 percent of energy from fat and are a significant
source of dietary cholesterol.
3. “Fat and cholesterol have nothing to do with
heart problems.”
Abundant scientific evidence establishes that dietary fat and cholesterol
are associated with increased cardiovascular disease risk.16
Nonetheless, some popular-press articles have incorrectly suggested
that evidence supporting this relationship is weak and inconsistent.
In addition, the late diet-book author Robert Atkins claimed in
interviews that, despite his having followed a fatty, high-cholesterol
diet for decades, he did not have artery blockages. The net result
may be that dieters believe they can safely disregard well-established
contributors to heart disease. After Dr. Atkins’ death, his
widow and his personal physician revealed that Dr. Atkins had indeed
had coronary artery blockages, although they have maintained that
these blockages had nothing to do with his death.
4. “Meat doesn't boost insulin; only carbohydrates
do that, and that's why they make people fat.”
Popular books and news stories have encouraged individuals to avoid
carbohydrate-rich foods, suggesting that high-protein foods will
not stimulate insulin release. However, contrary to this popular
myth, proteins stimulate insulin release, just as carbohydrates
do. Clinical studies indicate that beef and cheese cause a bigger
insulin release than pasta, and fish produces a bigger insulin release
than popcorn.15
Also, it is important to realize that different carbohydrate-rich
foods have very different effects. Most cause a gradual, temporary,
and safe rise in blood sugar after meals. Beans, green leafy vegetables,
and most fruits are in this healthful category. The main exceptions
are large baking potatoes, white bread, and sugary foods, which
can cause an overly rapid rise in blood sugar.
5. “People who eat the most carbohydrates tend
to gain the most weight.”
Popular diet books point out that cutting out carbohydrate-containing
foods may lead to temporary weight loss. This fact has been misinterpreted
as suggesting that carbohydrate-rich foods are the cause of obesity.
In epidemiological studies and clinical trials, the reverse has
been shown to be true. Many people throughout Asia consume large
amounts of carbohydrate in the form of rice, noodles, and vegetables
and generally have lower body weights than Americans—including
Asian Americans—who eat large amounts of meat, dairy products,
and fried foods. Similarly, vegetarians, who generally follow diets
rich in carbohydrates, typically have significantly lower body weights
than omnivores.
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