“Obesity and Dietary Recommendations” featured four academic experts examining different aspects of the obesity situation. Susan B. Roberts, Ph.D., senior scientist and director, Energy Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, and professor of nutrition and psychiatry, Tufts University, discussed the variance between psychology and biology in the etiology of obesity. The current Dietary Guidelines are geared toward people with a normal body-mass index (BMI)—a group that now constitutes only one-third of the U.S. population. Roberts spoke about the impact of dietary components such as fat and fiber, as well as high-variety diets that may meet more of the nutritional guidelines but don’t necessarily balance energy appropriately. She advised the next Dietary Guidelines team to consider both liquid energy intake and snack patterns in developing dietary guidelines, though cautioned it may not be possible to have a single dietary guideline for weight loss.
Alice H. Lichtenstein, D.Sc., professor of public health and family medicine, Tufts University, followed up on the topic by specifically discussing macronutrients and weight management. Studies now show weight loss and maintenance appear possible in a wide range of macronutrient intakes, whether low carb or low fat. Lichtenstein singled out the relationship between dairy intake and weight loss, noting studies suggest that calcium supplements may help decrease weight, but the jury is still out on dairy.
Barbara J. Rolls, Ph.D., professor of nutritional sciences, Penn State University, University Park, PA, presented an interesting take on the macronutrient issue. Rolls’ research focuses on portion control and energy density. Statistics have shown the introduction of larger portions coincides with the increase in the number of overweight people, while studies reveal greater portion sizes increase energy intake with no reported difference in hunger or fullness.
While existing solutions have revolved around portion-controlled meals, Rolls’ team has investigated the impact of reducing energy density in meals. In addition, she challenged industry to explore ways to incorporate greater quantities of fruits, vegetables and fiber to lower energy density of packaged goods while raising their nutrient profile and helping increase satiety.
The final point was raised by Leonard H. Epstein, Ph.D., professor of pediatrics and social and preventative medicine, State University of New York, Buffalo. Epstein focused on the ability of food to act as a behavioral reinforcer, a stimulus that modulates behavior. Individual differences placed on the value of food as a reinforcer of behaviors may impact obesity; for example, he suggested obese individuals may place more value on food and have fewer alternative reinforcers, increasing the motivation to get food.
