What Is Hypothalamic Obesity?
Hypothalamic obesity is a type of obesity that is caused when the hypothalamus doesn’t function normally. One of the most common reasons for a child to develop hypothalamic obesity is treatment for a brain tumor impacting the hypothalamus. Any injury to the hypothalamus can cause the condition. Genetic disorders affecting hypothalamic function can also lead to hypothalamic obesity.
The hypothalamus is located at the base of the brain, and while it is small, it regulates many important bodily functions like releasing hormones, controlling appetite, fluid balance, body temperature and sleep cycles, and maintaining the body’s internal energy balance (metabolic rate).
Abnormal hypothalamic function contributes to obesity in at least two fundamental ways: A child may have an abnormally high drive to eat (hyperphagia), and they may have a slow metabolism, which leads to decreased energy production, so they don’t burn as many calories. When both of these occur together, it can result in a rapid onset of weight gain. Abnormal hypothalamic function can also affect energy balance in many other ways, including disruption of hormone production, sleep,and circadian function, which in turn could lead to fatigue and less physical activity.
New research is also investigating how the hypothalamus might contribute to social functioning, which may also affect eating and activity behaviors.
Causes of Hypothalamic Obesity
Any injury to the hypothalamus due to a tumor, swelling in the brain, brain surgery or head trauma can result in hypothalamic obesity. Children treated with surgery or radiation for brain tumors — craniopharyngioma in particular — are at high risk for hypothalamic obesity. Swelling could come from intracranial infections, infiltrations, vascular problems and hydrocephalus (the buildup of fluid in the cavities deep in the brain). In some cases, a child is born with a hypothalamus that does not function typically as a result of a genetic disorder.
Signs and Symptoms of Hypothalamic Obesity
Rapid, sustained, excessive weight gain can indicate hypothalamic obesity. Children with hypothalamic obesity often continue to gain weight even when their food intake is limited, which can be different from children with other forms of obesity. Some patients, though by no means all, have uncontrollable hunger and may demonstrate abnormal food-seeking behavior, such as sneaking or stealing food.
Other symptoms include a low metabolic rate (the internal process of how the body expends energy and burns calories), less physical activity and excessive daytime sleepiness. Hypothalamic obesity often occurs in the setting of a brain tumor or other abnormality that produces hypopituitarism, or deficiency of pituitary hormones.
Tests and Diagnosis
In evaluating patients with possible hypothalamic obesity, doctors will conduct a physical examination and may order blood tests to check specific pituitary hormone levels. The hypothalamus and pituitary gland are connected and work together to deliver hormones.
In some individuals, a resting energy expenditure measurement is used to measure metabolic rate. A resting energy expenditure measurement is made after an overnight fast. Oxygen intake and carbon dioxide production are measured while a patient is awake and resting comfortably. If indicated, doctors may order a sleep study to assess for disordered sleep patterns. Testing for genetic disorders may also be indicated. Brain imaging is pursued in some cases.
Laboratory tests are also done for potential complications of hypothalamic obesity, including fatty liver disease and obesity-related diabetes.
Treatment of Hypothalamic Obesity
Appropriate pituitary hormonal replacement (if indicated), plus nutritional, physical activity, sleep and psychosocial interventions, are important components of management of hypothalamic obesity. For some individuals, medications may be appropriate for weight management or bariatric surgery may also be an option.
Our Neuroendocrinology Center team takes a multidisciplinary approach to find the right combination of treatment options that will help each child. Each family works with the team to create individualized management plans in the context of their child’s case. The most appropriate approach takes into account the unique needs and strengths of each child and family. Eating healthfully and staying physically active are important, and the best strategies incorporate the child’s developmental stage and health and the family’s goals.
The goal is to prevent the obesity related health problems that can occur in this condition and can impact a child’s quality of life. These complications can include: nonalcoholic fatty liver disease, diabetes, an abnormally high concentration of fats or lipids in the blood (high cholesterol or hyperlipidemia), high blood pressure (hypertension), sleep apnea, joint pain and abnormal sex hormone production. That is why the clinical team works with each family to create an individualized plan of early and sustained interventions.
The long-term outlook for children with hypothalamic obesity improves with treatments that limit excess weight gain and/or decrease the rates of obesity-related health problems. In addition, early identification and treatment of obesity-related health problems is important. Finally, children with this condition and their families benefit from assessment of psychosocial needs that may occur along with hypothalamic obesity.
Why Choose CHOP?
The Neuroendocrine Center at CHOP has substantial experience in the care of children with hypothalamic obesity and collaborates with CHOP’s Healthy Weight Program for patients and families interested that additional support.
In addition to endocrinologists, the center also has affiliated neurosurgeons, neuro-oncologists, neuro-ophthalmologists, neuroradiologists and geneticists who understand hypothalamic obesity and are available for consultation. CHOP Endocrinology dietitians provide important guidance on nutrition and physical activity, and social workers can provide psychosocial support.
We are constantly looking for more effective treatments through our active research program, including observational studies focused on better understanding the factors that contribute to hypothalamic obesity and clinical trials of novel therapies.