Overweight and Obesity - Causes - Causes

Energy imbalances, somegenetic or endocrine  medical conditions, and certain medicines are known to cause overweight or obesity.

Energy imbalances can cause overweight and obesity. An energy imbalance means that your energy IN does not equal your energy OUT. This energy is measured in calories. Energy IN is the amount of calories you get from food and drinks. Energy OUT is the amount of calories that your body uses for things such as breathing, digesting, being physically active, and regulating body temperature.

Overweight and obesity develop over time when you take in more calories than you use, or when energy IN is more than your energy OUT. This type of energy imbalance causes your body to store fat.

Your body uses certain nutrients such as carbohydrates or sugars, proteins, and fats from the foods you eat to:

• make energy for immediate use to power routine daily body functions and physical activity.
• store energy for future use by your body. Sugars are stored as glycogen in the liver and muscles. Fats are stored mainly as triglyceride  in fat tissue.

The amount of energy that your body gets from the food you eat depends on the type of foods you eat, how the food is prepared, and how long it has been since you last ate.

The body has three types of fat tissue—white, brown, and beige—that it uses to fuel itself, regulate its temperature in response to cold, and store energy for future use. Learn about the role of each fat type in maintaining energy balance in the body.

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Some genetic syndromes and endocrine disorders can cause overweight or obesity.

Genetic syndromes

Several genetic syndromes are associated with overweight and obesity, including the following.

• Prader-Willi syndrome
• Bardet-Biedl syndrome
• Alström syndrome
• Cohen syndrome

The study of these genetic syndromes has helped researchers understand obesity.

Endocrine disorders

Because the endocrine system produces hormones that help maintain energy balances in the body, the following endocrine disorders or tumor affecting the endocrine system can cause overweight and obesity.

• Hypothyroidism. People with this condition have low levels of thyroid hormones. These low levels are associated with decreased metabolism and weight gain, even when food intake is reduced. People with hypothyroidism also produce less body heat, have a lower body temperature, and do not efficiently use stored fat for energy.
• Cushing’s syndrome. People with this condition have high levels of glucocorticoids, such ascortisol, in the blood. High cortisol levels make the body feel like it is underchronic stress. As a result, people have an increase in appetite and the body will store more fat. Cushing’s syndrome may develop after taking certain medicines or because the body naturally makes too much cortisol.
• Tumors. Some tumors, such as craneopharingioma, can cause severe obesity because the tumors develop near parts of the brain that control hunger.

Medicines such as antipsychotics, antidepressants, antiepileptics, and antihyperglycemics can cause weight gain and lead to overweight and obesity.

Talk to your doctor if you notice weight gain while you are using one of these medicines. Ask if there are other forms of the same medicine or other medicines that can treat your medical condition, but have less of an effect on your weight. Do not stop taking the medicine without talking to your doctor.

Several parts of your body, such as your stomach, intestines, pancreas, and fat tissue, use hormones to control how your brain decides if you are hungry or full. Some of these hormones are insulin, leptin, glucagon-like peptide (GLP-1), peptide YY, and ghrelin.

• Research for Your Health will explain how we are using current research and advancing research to understand, prevent and treat overweight and obesity.
• Risk Factors will discuss family history, lifestyle, or other environmental factors that increase your risk of developing overweight and obesity.