Health

What Causes Obesity?

An Overview

Obesity is a term that refers to an excessive amount of body fat.

Although there are more accurate (and costly) ways to measure the amount of body fat, healthcare providers can estimate it by calculating the body mass index (BMI).

The cause of obesity is, quite simply, when a person consumes more calories from food than he or she is able to burn. You may be asking yourself, "I thought there were several causes of obesity, such as genetics, medicines, or diseases." It is important to understand that these are not causes of obesity. Instead, they are known as influences or risk factors for obesity. These risk factors increase a person's chances for obesity, but they do not "guarantee" obesity.

Some of these obesity risk factors include:
-Genetics
-Environmental factors
-Social factors
-Illnesses
-Medications.

Before we talk about these risk factors, it may help to understand a little bit about calories and metabolism.

Understanding Calories and Metabolism
Our bodies need calories to sustain life and be physically active. However, to maintain weight, we need to balance the energy we eat with the energy we use. When a person eats more calories than he or she burns, the energy balance is tipped toward weight gain and obesity.

This imbalance between calories-in and calories-out may differ from one person to another. Genetic, environmental, and other factors can all play a part in this imbalance. For example, we all have known someone who "could eat whatever they wanted to." In most cases, this person has been blessed with great genetics because what they burn on a daily basis (their metabolism, or "calories-out") is a lot higher than it is for the average person. There are also a number of factors that can have the opposite effect on metabolism by slowing it down, such as certain illnesses or medications.

Genetic "Causes" of Obesity
One risk factor for obesity is genetics. Obesity tends to run in families, suggesting a genetic cause. However, families also share diet and lifestyle habits that may contribute to obesity. Separating genetic influences from other risk factors for obesity is often difficult. Even so, science does show a link between obesity and heredity.

Environmental "Causes" of Obesity
Another risk factor for obesity is the environment, which strongly influences obesity. Most people who are alive today were also alive in 1980, when obesity rates were lower. Since this time, our genetic make-up has not changed, but our environment has.

Environment includes lifestyle behaviors, such as what a person eats and his or her level of physical activity. Too often, people eat out; consume large meals and high-fat foods, and put taste and convenience ahead of nutrition. Also, most people in the United States do not get enough physical activity.

Environment also includes the world around us – our access to places to walk and healthy foods, for example. Today, more people drive long distances to work instead of walking, live in neighborhoods without sidewalks, tend to eat out or get "take out" instead of cooking, or have vending machines with high-calorie, high-fat snacks at their workplace. Our environment often does not support healthy habits.

Social "Causes" of Obesity
Social factors, such as poverty and a lower level of education, have also been linked to obesity. One reason for this may be that high-calorie, processed foods cost less and are easier to find and prepare than healthier foods, such as fresh fruits and vegetables. Other reasons may include inadequate access to safe recreational places or the cost of gym memberships, limiting opportunities for physical activity. However, the link between low socioeconomic status and obesity has not been conclusively established, and recent obesity research shows that obesity is also increasing among high-income groups.

Medical Conditions That Can "Cause" Obesity
Some medical conditions may lead to or are associated with weight gain or obesity. Some of these conditions include:

Hypothyroidism
Hypothyroidism is a condition in which the thyroid gland fails to produce enough thyroid hormone. It often results in a lower metabolic rate and loss of vigor.

Cushing's Syndrome
Cushing's syndrome is a hormonal disorder caused by prolonged exposure of the body's tissues to high levels of the hormone cortisol. The symptoms of this condition vary, but most people have:
-Upper body obesity
-A rounded face
-Increased fat around the neck
-Thinning arms and legs.

Polycystic Ovarian Syndrome
Polycystic ovarian syndrome, or PCOS for short, is a condition characterized by high levels of androgens (male hormone), irregular or missed menstrual cycles, and, in some cases, multiple small cysts (fluid-filled sacs) on the ovaries.

Medications That "Cause" Obesity
Certain drugs, such as steroids, some antidepressants, and some medications for psychiatric conditions or seizure disorders, may also cause weight gain. These drugs can slow down the rate at which the body can stimulate appetite and burn calories, and can cause the body to hold on to extra water.

Other "Causes" of Obesity
A lack of sleep may also contribute to obesity. Recent studies suggest that people with sleep problems may gain weight over time. On the other hand, obesity may contribute to sleep problems due to medical conditions. For example, a person who has sleep apnea briefly stops breathing multiple times during the night.

A Summary of the Causes of Obesity
There are a number of factors that increase a person's chances for developing obesity, including genetic, environmental, and social factors, as well as certain medical conditions and medications. Some people may consider these obesity risk factors to be "causes of obesity," but they are not, because they do not "guarantee" obesity. In all of these cases, the underlying cause of obesity is eating more calories than the body can burn – for whatever reason.

If you are overweight or obese, the good news is that you can do something about it. The first step is understanding the obesity risk factors that apply to you. The next step is starting the process of consuming fewer calories than you burn.

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