Author + information
- Received September 25, 2009
- Accepted September 30, 2009
- Published online March 2, 2010.
- Denise G. Simons-Morton, MD, PhD⁎ (, )
- Karen Donato, SM,
- Catherine M. Loria, PhD,
- Charlotte A. Pratt, PhD,
- Abby G. Ershow, ScD,
- Meredith A. Morrissette, MPH,
- Susan Czajkowski, PhD,
- S. Sonia Arteaga, PhD and
- Eva Obarzanek, PhD
- ↵⁎Reprint requests and correspondence:
Dr. Denise Simons-Morton, Division of Cardiovascular Sciences, National Heart, Lung, and Blood Institute, 6701 Rockledge Drive, Suite 10018, MSC 7936, Bethesda, Maryland 20892-7936
To address the well-recognized and growing public-health problem of obesity in the U.S., the National Heart, Lung, and Blood Institute (NHLBI) supports a robust portfolio of obesity-related research and translation activities and a trans-NHLBI Obesity Working Group. The NHLBI also has a leadership role in the Obesity Research Task Force of the National Institutes of Health. Here, we summarize major obesity-related activities in which the NHLBI was the lead institute over the past several decades, including those addressing lifestyle factors of diet and physical activity. We categorize the activities into 4 areas: 1) epidemiologic and basic research; 2) efficacy clinical trials; 3) effectiveness studies; and 4) obesity-related translation and dissemination activities. These activities inform each other bidirectionally (Fig. 1).
Epidemiologic and Basic Research
The NHLBI's longitudinal cohort studies have provided a wealth of scientific evidence over the past several decades on the importance of obesity as an independent risk factor for morbidity and mortality. Studies involving adults, such as the Framingham Heart Study and the ARIC (Atherosclerosis Risk in Communities) study, have identified many health consequences of obesity, including cardiovascular diseases (CVDs), pulmonary diseases, CVD risk factors, and sleep disorders (1,2). Cohort studies in youth, particularly the Muscatine Heart Study (3,4) and the Bogalusa Heart Study (5), as well as the CARDIA (Coronary Artery Risk Development in Young Adults) study (6), have provided invaluable information about CVD risk factor development and consequences. In response to observations that maturation through adolescence is a particularly vulnerable time for obesity development in girls and the recognition of differential obesity development by race, the NHLBI sponsored the NGHS (NHLBI Growth and Health Study), which specifically focused on obesity development by examining patterns and predictors of weight-gain trajectories in black girls and white girls followed up for 10 years from pre-pubertal ages (7,8).
Findings from the NHLBI cohort studies have been critical to understanding the rise in obesity over time and to the recognition that numerous factors in youth, especially those that are obesity related, affect future CVD risk in adulthood. These studies have identified population groups at higher risk for obesity and its consequences as well as modifiable factors associated with weight gain—findings that have informed intervention approaches and translation programs. Additional analyses in the cohort studies are ongoing, including associations between genes and obesity-related factors, and examination of the role of the built environment on obesity-related lifestyle behaviors and weight gain.
The NHLBI also has solicited and supports a portfolio of basic mechanistic research studies in humans and in animal models examining pathophysiologic mechanisms of the effects of obesity on the full array of CVDs, including coronary artery disease, peripheral arterial disease, heart failure, and congenital heart disease. Ongoing NHLBI-solicited studies also are examining relationships between obesity and sleep disorders. A new effort is funding translational research from basic behavioral and social sciences to improve understanding of obesity-related behaviors and inform development of promising new intervention approaches. Because accurate data on diet and physical activity are essential for understanding energy balance and gene–environment interactions, the NHLBI also supports bioengineering-oriented and technology research for novel methods and devices to improve assessment of food intake and energy expenditure as well as body composition, tissue lipid content, and metabolic status.
Efficacy Clinical Trials
Randomized controlled trials (RCTs) designed to determine effects of interventions under tightly controlled conditions are an important part of the NHLBI obesity-related research portfolio. NHLBI-supported RCTs have tested the efficacy of various lifestyle approaches for CVD prevention, including aspects of nutrition and physical activity, and have tested intervention approaches to prevent or reduce obesity.
Efficacy studies of nutrition and the CVD risk factors of elevated cholesterol and blood pressure (BP) have used outpatient feeding methods in which participants were given all of their food, and high compliance was assured. These trials include the DELTA (Dietary Effects on Lipoproteins and Thrombogenic Activity) (9,10) trial, the DASH (Dietary Approaches to Stop Hypertension) trial (11), and the DASH-Sodium trial (12). Findings showed that the CVD risk factors of hypercholesterolemia and BP are substantially affected by dietary composition, such as saturated fats and fruits and vegetables, and nutrients such as sodium, even when body weight is not changed.
Efficacy trials also have tested the effects of relatively intensive lifestyle behavioral interventions, which include weight loss, on CVD risk factors. The Trials of Hypertension Phase II tested effects on hypertension incidence of weight loss and dietary sodium reduction, separately and together (13). On the basis of findings from the studies noted in the preceding text, the PREMIER trial examined interventions to help people with elevated BP adopt the full array of lifestyle approaches previously shown to improve BP control, including weight loss, reduction in dietary sodium, and the DASH dietary pattern (14,15).
Large NHLBI-supported trials also have tested interventions to improve weight loss or weight loss maintenance in overweight or obese adults. The POUNDS (Preventing Overweight Using Novel Dietary Strategies)-Lost trial found that macronutrient composition of diets is less important than calories for weight loss over 2 years (16). The Weight Loss Maintenance Trial found that a personal contact intervention was modestly more successful than other strategies in maintaining weight after successful weight loss (17).
In youth, the DISC (Dietary Intervention Study in Children) found that a dietary intervention focusing on dietary fat modification can be safe through the peripubertal period and can significantly but modestly reduced elevated low-density lipoprotein cholesterol levels over a period of 3 years (18). The 4-study program involving high-risk African-American girls, called GEMS (Girls Health Enrichment Multi-Site Studies), confirmed the value of pilot testing interventions before conducting efficacy trials of promising obesity-prevention approaches (19).
On the basis of findings from the CARDIA cohort study, newly funded trials will test various intervention approaches on weight control in young adults 18 to 35 years old at high risk for weight gain. New trials are planned that will build on prior findings to test effects of promising innovative approaches to prevent and/or treat obesity in children and adolescents.
Effectiveness Studies in Community Settings
Intervention studies in real-world settings—including communities, work sites, schools, and community clinical practice—provide important evidence for practice. NHLBI-supported effectiveness studies generally test interventions modified for more practical use from those successful in efficacy trials. Study designs include group randomized trials or quasi-experimental studies, in which groups such as communities, schools, or work sites are assigned to intervention or comparison conditions.
Community studies funded by NHLBI in the 1980s took a broad, community perspective to reducing CVD risk: the Stanford Five-City Project (20), the Minnesota Heart Health Program (21), and the Pawtucket Heart Health Program (22). The experience from these studies was invaluable for understanding how to work with communities and community organizations to promote health. The NHLBI solicited and is supporting studies in work sites on control of overweight or obesity that are testing effects of environmental interventions, such as changes in cafeteria food offerings or policies to allow time off for physical activity (23). NHLBI-solicited studies of prevention approaches also have worked with disadvantaged populations, including ongoing studies of community-responsive interventions in American Indian communities for improvements in lifestyle and reductions in obesity.
To help inform clinical practice, the NHLBI has sponsored effectiveness studies in community clinical practice settings that test interventions to improve diet, physical activity, and/or obesity. The ACT (Activity Counseling Trial) compared several patient education and counseling approaches to improve physical activity levels of primary care patients (24). The ongoing POWER (Practice-based Opportunities for Weight Reduction) trials are testing approaches to reduce weight in obese primary care patients who also have additional CVD risk factors (25).
Among youth, several NHLBI school-based studies have tested approaches for CVD health promotion and disease prevention. The Child and Adolescent Trial for Cardiovascular Health tested a heart-healthy program combining curricular offerings with school environment changes (26). The Pathways trial also used a multilevel school-based approach to specifically address obesity prevention in American Indian schoolchildren (27). The Trial of Activity in Adolescent Girls tested a school-community linked intervention to help prevent the decline in physical activity seen during adolescence (28). From these studies, we have learned the importance of combining environmental and individual intervention strategies. Many local programs and policies to help control obesity or improve healthful lifestyles are occurring throughout the nation, so the NHLBI is planning a new study to examine this natural experiment with the goal of identifying effective local actions to help control childhood obesity rates.
Translation and Dissemination Activities
The NHLBI has translated obesity research into best practices for prevention and treatment through the Obesity Education Initiative. Clinical guidelines for adults, released in collaboration with the National Institute of Diabetes and Kidney Disease in 1998, provide guidance on body mass index and waist circumference cutpoints for defining overweight and obesity in adults, as well as evidence-based guidelines for treatment options (29). An expert panel currently is working to update the guidelines based on a systematic review of more-recent evidence. The NHLBI also develops and provides tools to help clinicians and patients follow the clinical guidelines; those related to obesity are available on the Aim for a Healthy Weight website. The NHLBI also has sponsored training grants to foster translation into clinical practice by health professionals; the Nutrition Academic Award focused on nutrition training in medical and other health professional schools including obesity topics (30).
In response to substantial increases in childhood obesity, the NHLBI in collaboration with other National Institutes of Health Institutes launched We Can! (Ways to Enhance Children's Activity and Nutrition) in 2005. Currently in >1,100 community sites in all 50 states, the program focuses on healthful lifestyle behaviors through community outreach, national partnerships, and media. The NHLBI will soon release integrated cardiovascular clinical guidelines for children and adolescents as part of the Pediatric Cardiovascular Risk Reduction Initiative. The guidelines will address CVD risk factor identification and risk reduction in children, with obesity as 1 important component.
We have learned much, and are still learning more, from the obesity and lifestyle research supported by the NHLBI. We have learned about effects of obesity on morbidity and mortality, effects of childhood obesity on future health, effects of weight reduction on CVD risk factors, associations of various factors with obesity development, effects of various interventions on weight loss and weight-loss maintenance, and effectiveness of interventions in communities, schools, work sites, and community clinical practice settings. The various types of research—including basic mechanistic research, epidemiology, efficacy trials, and effectiveness studies—inform each other. The research findings also inform translation programs. While the NHLBI continues to support scientists to conduct research on all aspects of obesity, we will also continue to translate the latest knowledge into practice. Our goal is to improve the public's health by developing and translating the evidence-base for action in this critical public-health area.
- Received September 25, 2009.
- Accepted September 30, 2009.
- American College of Cardiology Foundation
- Hubert H.B.,
- Feinleib M.,
- McNamara P.M.,
- Castelli W.P.
- Burns T.L.,
- Moll P.P.,
- Lauer R.M.
- Lloyd-Jones D.M.,
- Liu K.,
- Colangelo L.A.,
- et al.
- Ginsberg H.N.,
- Kris-Etherton P.,
- Dennis B.,
- et al.
- Berglund L.,
- Lefevre M.,
- Ginsberg H.N.,
- et al.
- The Trials of Hypertension Prevention Collaborative Research Group
- Obarzanek E.,
- Kimm S.Y.,
- Barton B.A.,
- et al.
- Obarzanek E.,
- Pratt C.A.
- Caballero B.,
- Clay T.,
- Davis S.M.,
- et al.
- Eaton C.B.,
- McBride P.E.,
- Gans K.A.,
- Underbakke G.L.