9
Research Recommendations
The committee identified areas where additional research would be useful as it assessed data obtained from its umbrella reviews. This chapter presents those research gaps and recommendations to fill them, which span four topic areas: factors affecting energy requirements, energy metabolism in special population groups, weight change and energy metabolism, and application of the Estimated Energy Requirement (EER) to individuals and population groups.
FACTORS AFFECTING ENERGY REQUIREMENTS
Limited data and systematic review evidence are available on how factors such as macronutrient composition of the diet, the gut microbiome, dietary fiber, and genetic factors affect energy requirements at all life stages. Such information would be particularly valuable for individuals participating in doubly labeled water (DLW) studies.
To better determine the EER for pregnant women, more DLW data and body composition data on pregnant women is needed across all prepregnancy body mass index (BMI) categories. These data could be analyzed to identify energy needs of pregnant women who have gained within the Institute of Medicine 2009 gestational weight gain recommendations and pregnant women who have gained outside of those recommendations.
Research Recommendation 1
The committee recommends that the National Institutes of Health (NIH), the U.S. Department of Agriculture (USDA), the Centers for Disease Control and Prevention (CDC), the Department of Veterans Affairs (VA), and Health Canada commit funding to nutrition and kinesiology research that would inform future updates of the Dietary Reference Intakes (DRIs) for energy in all sex and life-stage groups. The committee further recommends research on methodologies to individualize energy requirements when providing precision nutrition care.
ENERGY METABOLISM IN SPECIAL POPULATION GROUPS
Energy metabolism data on diverse racial/ethnic groups, including indigenous populations in the United States and Canada, is scarce. Along with a research focus on more diverse population groups a critical research need is the inclusion of ancestry data in order to stratify study participants. Also lacking is evidence on factors that affect energy metabolism and energy requirements in transgender populations.
The effect of sarcopenic obesity on energy requirements in individuals of all age, sex, and BMI groups is not well understood, nor is energy balance, energy expenditure, and energy compensation in individuals with BMI ≥ 50. Additionally, data from DLW studies is lacking for infants, children, adolescents, the oldest old, and lactating women.
Given the increasing prevalence of chronic disease and other diet-related risk factors across the U.S. and Canadian populations, evidence is needed on medications that affect energy metabolism. In addition, research is needed on how medications and procedures such as bariatric surgery affect energy metabolism, especially total energy expenditure (TEE).
Research Recommendation 2
The committee recommends that NIH, USDA, CDC, VA, and Health Canada commit funding to nutrition research that would inform future updates of the DRIs in diverse populations, including infants, children, and adolescents, the oldest old, lactating women, and individuals taking medications and those at higher body mass index (BMI) levels.
WEIGHT CHANGE AND ENERGY METABOLISM
There is insufficient evidence on defining a weight cycle and determining what frequency, amount, and duration of cycling indicates a significant effect on energy metabolism. In addition, reporting on how
weight change is measured is inconsistent and information on population characteristics and research methodologies relating to the measurement of body weight are inadequately reported in many research articles.
Research Recommendation 3
The committee recommends that investigators studying energy balance and national health surveillance monitoring provide participants’ rationales for weight gain or weight loss. In addition, published research reports should indicate whether weight change was measured or self-reported. Nutrition and kinesiology researchers should also use accepted definitions that differentiate basal and resting metabolic rate to standardize terminology in reporting study findings.
Research Recommendation 4
The committee further recommends that research agencies develop a checklist of quality factors (to guide study designs and protocols and to evaluate study quality) that are relevant to evaluating energy intake imbalances and to relating intake imbalances to health outcomes. Journal editors should require documentation from authors to show that articles accepted for publication have met quality factors for assessing energy intake imbalances.
APPLICATION OF THE EER TO INDIVIDUALS AND POPULATION GROUPS
To support translation to population-level survey data and application for recommendations, research is needed on the relationship between total energy expenditure and physical activity levels (PALs) with metrics that define physical activity intensity and duration. This could be facilitated by including devices to measure steps and physical activity in DLW studies as well as self-reported physical activity behavior. There is a paucity of DLW-derived PALs with metrics in the pediatric population (infants, children, and adolescents).
Because of the complexity in factors associated with the selection of the PAL and calculating the EERs, there is a potential for error in the calculation of the EER owing to misclassification.
Research Recommendation 5
The committee recommends that USDA, the U.S. Food and Drug Administration, NIH, and Health Canada commit funding to develop an app to facilitate calculations of EERs for specific life-stage groups to ensure the wide
dissemination and appropriate application of the new EERs. Additionally, CDC and Canada’s Health Statistics agencies should incorporate into their national health surveys measures of physical activity that are compatible with the physical activity level (PAL) categories needed to calculate EERs. Those U.S. and Canadian agencies that fund research to support public health initiatives should invest in development and validation of measures of physical activity that can be used in public health and research contexts.