...From the pages of Agricultural Research magazine
ForumWhen Too Much of a Good Thing Is Bad
While food shortages have plagued humankind through much of history
and remain a stark reality for millions of the world's poor, health
experts are now reporting that there are as many overweight people in
the world today as there are undernourished.
Food is the stuff of life, but what and how much we eat is often at
the root of what ails us. Dietary intake is linked to risks for developing
a variety of chronic diseases that are disabling and life threateningnot
only for the underfed, but also for the overweight.
Body mass index (BMI), expressed as weight divided by height (squared),
is commonly used to classify overweight and obesity among adults (age
20 years and over). An estimated 64 percent of U.S. adults are either
overweight or obese, according to a 1999-2000 federal survey. The U.S.
Centers for Disease Control and Prevention (CDC) estimates that 21 percent
of adults are obese. Severe health problems, including diabetes, heart
disease, high blood pressure, kidney problems, some types of cancer,
and arthritis, affect the obese at a higher rate. A recent analysis
by CDC found that treatment of illnesses related to obesity costs the
United States $93 billion a year, rivaling the costs of smoking-related
According to recent studies, 1 in every 50 adults in the United States
is at least 100 pounds overweight. Extreme obesity was once thought
to be rare, but new evidence finds the number of obese Americans quadrupled
from 1986 to 2000. Though genetics can play a role, the combination
of overeating and underactivity has led to an epidemic of overweight
and obesity in our country.
One component of the ARS Human
Nutrition program is to study diet, genetics, lifestyle, and prevention
of obesity and disease. Human Nutrition is a major program area of ARS.
Its goals are to ensure the United States continues to provide a nutritious
food supply and to promote nutritional health and quality of life among
its citizens. It also aims to reduce morbidity and mortality associated
with chronic diseases influenced by dietary intake and to conduct research
that can be used to develop sound dietary recommendations and establish
more effective food-assistance programs.
About 15 percent of children and adolescents ages 6 to 19 are now seriously
overweight, according to the CDC. This percentage has more than doubled
since the early 1970s. A collaborative study by ARS scientists in Beltsville,
Maryland, and Boston and researchers at Harvard University found decreased
nutritional dietary quality and increased caloric intake among U.S.
children on days when they consumed fast food. ARS scientists in Houston
showed that providing young children with opportunities to select their
own portion sizes resulted in their selecting smaller portions and eating
less. Another ARS study in Houston is examining Hispanic children to
see whether genetic and environmental factors contribute to childhood-onset
obesity in this ethnic group.
These findings warn us that another generation of overweight adults
may be facing eventual weight-related health conditions.
The Lower Mississippi Delta Nutrition Intervention Research Initiative
(Delta NIRI) is a partnership between ARS and six institutions of higher
education to determine the nutrition-related health of the population
bordering the Mississippi River in Arkansas, Louisiana, and Mississippi.
Residents in these three Delta states have a disproportionate occurrence
of chronic diseases related to overweight, obesity, and lack of physical
activities. (See story
on page 4.)
An ARS research study in Boston found that a low-fat, low-calorie regimen
may not only help Americans lose weight, but may also boost the immune
system. Boston researchers are also studying the dietary habits of healthy
people to see which foods make people gain weight. Studies done in collaboration
with university researchers found that participants who ate three servings
of whole grains per day had significantly lower BMIs. (See story
on page 8.)
Because Congress requires USDA to survey the food intake of Americans,
ARS uses a new research procedure called the Automated Multiple Pass
Method to effectively gauge people's food consumption. Using survey
data, ARS researchers examine diets as a factor in select diseases and
help public policy officials make decisions about food safety and food
fortification. (See story
on page 10.)
Knowing which factors lead to food choices and how behavior affects
our food intake will help researchers develop intervention strategies
that can be used to change unhealthy choices in at-risk populations.
ARS human nutrition research addresses the nutrient requirements needed
for health, quality of life, prevention of diet-related chronic diseases,
and the promotion of a nutritious food supply.
ARS currently has a network of six human nutrition research centers across the United States, plus the Delta NIRI. ARS is committed to research that furthers our understanding of the interrelationships between diet, genetics, and health as well as applying and validating strategies to stimulate healthy food, nutrition, and lifestyle behaviors. Projected long-term outcomes include improving the food supply and understanding why consumers make the food choices they do and how those choices might be modified to promote health.
Joseph T. Spence
"Forum" was published in the June 2004 issue of Agricultural Research magazine.