The Effects of Your Food’s Energy Density
from the AICR Newsletter | Fall 2014 | No.125
Terry Hartman, PhD, MPH, RDN
With AICR funding, Terry Hartman, PhD, MPH, RDN – of the Rollins School of Public Health at Emory University in Atlanta – is examining how the energy density of our diets affects body weight and other markers of cancer risk.
Q. Please describe your current AICR-funded research study.
A. My colleagues and I designed this research to explore how energy density of the diet is associated with overweight and obesity, waist size and markers of inflammation and insulin resistance. These factors are linked with an increased risk of several cancers. They include post-menopausal breast cancer, female gynecologic cancers, as well as cancers of the colon and esophagus. We’re using data from the National Health and Nutrition Examination Survey (NHANES), collected by the National Center for Health Statistics.
Q. Why did you choose NHANES?
A. It’s quite a large sample and represents adults across the United States. A lot of studies collect information about height, weight and waist circumference by simply asking the subjects. NHANES uses trained staff to measure these things. Trained interviewers use a standardized protocol to gather information about the diet. All of this makes us more confident that we are getting reliable information.
Q. What is energy density?
A. Energy density – sometimes called calories density – is the amount of calories in a given weight of food. Foods high in energy density, like brownies, have more calories per ounce than foods low in energy density, like an orange or carrots.
My colleague Dr. Barbara Rolls at Penn State University has shown that people tend to eat about the same weight of food from one day to the next. When we replace high energy-dense foods with low energy-dense foods, we can eat about the same weight of food for fewer calories. That can help control weight.
Q. Can you share your findings so far?
A. Eating a high energy-dense diet is linked with overweight and obesity. We found that both body mass index and waist circumference increased as the energy density of the diet increased. In fact, individuals who consumed the diets highest in energy (calories) were about 50 percent more likely to be obese, even after controlling for age, race, socioeconomic status and physical activity.
Women who ate a high energy-dense diet tended to have higher insulin levels – a marker of insulin resistance – measured when they were fasting.
Q. How can we reduce the energy density of our diets?
A. Fruits and vegetables tend to be low in energy density. Eat them instead of higher energy-dense foods. Instead of starting your day with a sweet roll, eat high-fiber cereal with skim milk. At lunch, trade high-fat sides like chips for a salad. Start dinner with a broth-based soup instead of a creamy soup.
Q. Besides increasing the risk of being overweight or obese, how could the energy density of a person's diet contribute to higher cancer risk?
A. People who consume low energy-dense diets get the benefit of more fiber [which helps prevent colorectal cancer and promotes bowel health], vitamins and phytochemicals.