Obesity has risen to epidemic levels in the United States and it is a major public health challenge. Individuals who have obesity are at risk for developing devastating health problems, may face reduced life expectancy, and may experience stigma and discrimination. Obesity is a strong risk factor for type 2 diabetes, fatty liver disease, and many other disorders within the NIDDK’s mission. More than 40 percent of U.S. adults have obesity, and more than 18 percent of children and adolescents have obesity. Obesity disproportionately affects people from certain racial and ethnic groups and those who are socioeconomically disadvantaged. NIDDK-supported research through the years has improved our understanding of body weight regulation and yielded new treatment approaches for people with obesity.
- The percent of adults and children with obesity (BMI ≥ 30) increased dramatically in the U.S. beginning in the 1980s. The prevalence of severe obesity, which carries even greater health risks, also increased.
- The estimated annual medical cost of obesity in the United States was $147 billion in 2008 US dollars.
- While environmental factors such as increased portion sizes, an increase in readily available high calorie foods with low nutritional value, and more sedentary activities play a role in the obesity epidemic, biological factors, including genetics and epigenetics as well as hormonal and metabolic factors, also contribute.
- The 1994 discovery of the hormone leptin, which is produced by fat cells, illuminated how body fat is not just a storehouse for calories. Leptin acts on receptors in the brain to influence appetite and calorie burning. This discovery ignited vast research on biological factors that influence body weight. These studies, including many NIDDK-supported, showed that there is a robust physiologic system that regulates food intake and metabolism. This research demonstrated that obesity is not simply a matter of will power, but has complex causes involving interactions between our physiology, genes, behaviors, and environments.
Today and Tomorrow
The Role of Basic Science in Obesity Research
- NIDDK-supported research is exploring the role of the gut microbiome in obesity development. Evidence suggests that gut microbiome composition can predict body composition (lean and obese) with high accuracy, and the microbiome plays an important role in weight loss intervention outcomes. In addition, NIDDK supports research aimed at activating brown fat, a form of fat that burns calories to generate heat.
- Due to NIDDK’s research efforts, people can be treated with microbial-targeted therapeutic strategies to improve weight outcomes. Moreover, scientists will have identified safe and effective treatments to activate brown fat and treat metabolic disease.
The Importance of Early Obesity Prevention
- Rapid weight gain in early childhood increases the risk for obesity later in life, so early prevention is critical. An NIDDK-supported randomized clinical trial, the Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) study, showed that a responsive parenting intervention initiated early in infancy and designed to prevent rapid infant weight gain resulted in a modest reduction in body mass index (BMI) compared to the average BMI at 3 years of age. Study investigators are now following the INSIGHT participants for several more years to build upon knowledge gained in the initial study. NIDDK, along with other Institutes, is also currently inviting research applications to understand factors in infancy and early childhood that influence obesity development.
- New approaches to prevent the development of childhood obesity will be identified through NIDDK-supported research that will allow early identification of children at risk, and targeted prevention strategies likely to be effective. Early prevention will allow more people to enjoy longer, healthier lives without the complications and co-morbidities of obesity.
Lifestyle Interventions as a Treatment Strategy
- The NIDDK-funded Look AHEAD (Action for Health in Diabetes) randomized clinical trial showed that through an intensive lifestyle intervention involving increased physical activity and healthy eating, people with obesity and type 2 diabetes (T2D) are able to reach and maintain a clinically meaningful weight loss. The study enrolled more than 5,100 adults ages 45-76 with overweight/obesity and T2D, and the intervention lasted up to 11 years. The participants in the intervention successfully achieved weight loss goals and enjoyed many other health benefits, although the intervention did not lower risk of cardiovascular events. The intervention phase has ended, but the investigators continue to follow participants to evaluate longer-term outcomes related to obesity, diabetes, and aging.
- Obesity treatment will move away from a “one-size-fits-all” approach and toward personalized medicine. While interventions can achieve successful weight loss, there is heterogeneity in their effectiveness due to individual genetic and environmental variability. In the future, health care providers will be able to predict a patient’s personal responses to different interventions through genetic testing and other assessments, along with consideration of what is feasible in the environment in which each person lives, so that the right treatment can be delivered to the right person at the right time. This precision approach will take into consideration personalized diet, nutrition, and physical activity needs.
Surgical Intervention as a Treatment Strategy
- The NIDDK-supported Teen-LABS (Longitudinal Assessment of Bariatric Surgery) is an observational study assessing the short- and long-term risks and benefits of bariatric surgery in teens who have severe obesity and serious weight-related health problems. Researchers found major improvements in weight, heart health, prediabetes, type 2 diabetes, blood pressure, cholesterol, and kidney function 3 years after surgery. Moreover, 5 years after weight-loss surgery, researchers compared the results for teens in the study to results for adults who had the same procedure. While weight loss was substantial and similar between the two groups, teens with type 2 diabetes before surgery were more likely than adults to have their diabetes resolve after surgery without diabetes medications. Teens were also more likely than adults to no longer have high blood pressure after surgery or take blood pressure medications.
- In the future, researchers will develop novel treatments that provide the benefits of bariatric surgery non-invasively, based on advanced understanding of how bariatric surgery has its effects. People with obesity and its complications can look forward to the same health benefits through non-surgical means.