The Science of Obesity

As scientists work to unravel the complex processes that regulate appetite, metabolism and weight management, each discovery and insight brings us closer to understanding weight gain and the challenges of losing weight, keeping it off and staying healthy.

More in-depth understanding of the body’s chemical and hormonal regulatory processes can help researchers design drugs and therapies that target specific systems. One of those influential hormones studied at UMMC is leptin, which is secreted by fat.

Normally, leptin acts on the brain to suppress appetite and stimulate energy expenditure in the muscles and other tissues. But the more obese a person gets, the more leptin he or she produces, causing the brain to become increasingly resistant to some of the hormone’s effects. In a leptin-resistant brain, the hormone raises blood pressure but no longer helps expend energy, and it doesn’t suppress appetite effectively. That contributes to a cycle where an obese person burns fewer calories, feels hungrier and develops high blood pressure.

Through continued research, scientists can potentially design drugs that control leptin’s effects, including its tendency to create high blood pressure, a major contributor to heart disease.

Tackling leptin is just one corner of the picture. For instance, at least 80-90 percent of people who’ve lost substantial weight regain it over time. Researchers are beginning to understand some of the factors contributing to these high recidivism rates – environment, behavior, endocrine and hormone system responses, genetics, neighborhoods, cultures and stress, among other factors – but unraveling exactly how some of those factors work is more difficult.

For example, levels of certain hormones, including ghrelin and peptide YY, in people who recently lost weight are different than in consistently slim people. In weight-loss groups, hormone levels indicate their bodies kick into starvation-response mode to try to regain the weight.

Given all the complexities that influence how we gain, lose and maintain weight, researchers need a full range of methods to uncover the science of obesity. From lab-based analysis of hormones and metabolism to psychological studies of food addiction, to population studies that follow groups of people through months and years, all these methods take financial support. The more scientists can discover about the many factors surrounding obesity, the more accurate and relevant knowledge we’ll have to fight it.