What Are the Causes of Weight Gain


Weight gain is not only the result of overeating and under exercising. Medical researchers have uncovered a number of reasons people cannot control their weight, from stress to genetics. In this article we take a look at a few of the major reasons people gain weight.

Medications that Can Cause Weight Gain

Prescription medications can increase the appetite, slow down metabolism, change the way the body stores fat, and affect insulin levels—all of which can contribute to weight gain. Different medications have different effects on weight, and effects of the same medication can vary from individual to individual.

  • Coricosteroids (e.g., prednisone, cortisone, and hydrocortisone) are prescribed to treat a variety of conditions, including lupus, asthma, and rashes.
  • Cyproheptadine, which is prescribed to relieve allergies and related conditions;
  • Diabetes medications;
  • Anti-seizure medications;
  • High blood pressure medication;
  • Heartburn medication;
  • Lithium—an antimanic agent used in the treatment of bi-polar disorder;
  • Tranquilizers;
  • Antipsychotics (e.g. phenothiazine);
  • Other medications that increase fluid retention and cause edema; and
  • Anti-depressants. Certain anti-depressants are more likely to cause or contribute to weight gain than others.  Researchers estimate that anti-depressants cause weight gain in up to one-quarter of the people who take them.  Anti-depressants that may cause weight gain include SSRIs (selective serotonin reuptake inhibitors) such as lexapro, paxil, prozac, and zoloft.

Medical Conditions that Contribute to Weight Gain

Weight gain accompanies many different medical conditions:

  • Hypothyroidism is a deficiency of the thyroid hormone. A deficiency in this hormone depresses the metabolism, which in return causes weight gain.
  • Weight gain associated with Cushing’s syndrome is due to an excess of the hormone cortisol, which results in a build-up of fat in the upper back, abdomen, and face.
  • Certain heart and lung disorders involve fluid retention, which increases weight.
  • Polycystic ovary syndrome, which is an imbalance in a woman’s female sex hormones, can cause weight gain.
  • Sleep apnea, which affects hormone levels and interferes with sleep.
  • Leptin is a hormone that regulates weight; people may become overweight as a result of low leptin levels.
  • The hormone insulin does not work as it should in people who are insulin resistant, resulting in excessive accumulation of sugar in their bodies. Insulin resistance can result in weight gain, and can also lead to type II diabetes.
  • Some people eat more and thus gain weight when they are depressed in an attempt to relieve the depression.

Weight gain may be a symptom of an underlying condition that requires medical attention. Individuals who experience any of the following symptoms along with weight gain need to see their healthcare providers.

  • Constipation;
  • Hair loss;
  • Sensitivity to cold;
  • Swollen feet along with shortness of breath;
  • Changes in vision;
  • Uncontrollable hunger along with heart palpitations, tremors, and sweating; or
  • Excessive weight gain for no apparent reason.

Aging and Other Natural Events that Cause Weight Gain

Weight gain naturally accompanies a number of events in the normal life cycle of a human being. While not all people gain weight with age, many do, at least partly because their metabolisms slow down.

It is common for women to gain weight at puberty, during pregnancy, and at menopause. Gaining weight is part of maturing into adulthood. As boys and girls approach puberty their bodies change shape and become heavier.

What are the Causes of Weight Gain Related to Lifestyles?

As most people know, maintaining weight requires a balance between the calories that come in and the calories go out. Eating too much is most common cause of weight gain. A recent study by the World Health Organization concluded: “The main reason that obesity has risen sharply in the United States in recent decades is predominantly because of overeating.”

High carbohydrate and high fat diets contribute more to weight gain than do low carb/low fat diets. Highly processed food and junk food are high-calorie foods that have a direct relation to weight gain.

Studies show that inactivity and overweight are connected. While the exact nature of the connection between the two is still open to debate, a healthy diet combined with regular exercise is the most basic way to avoid becoming overweight or obese.

People may gain weight from moderate to excessive consumption of alcohol. Alcohol is a refined carbohydrate, like sugar and white flour—all of which add calories to any diet. Plus, for some people alcohol may raise blood sugar and insulin levels, two conditions that can play roles in weight gain.

Many people experience a temporary weight gain when they quit smoking. Often this is because they eat more to make up for lack of cigarettes. This type of weight gain usually passes once non-smoking becomes part of life.

Some people eat less when they are stressed and some eat more. Many are so consumed with their difficulties that they do not eat healthy meals. Stress eating or emotional eating is a common reaction to stress: people eat higher calorie foods in an effort to fill their emotional needs. Stress can also lead to inactivity, which can then lead to weight gain.

Believe it or not, a good night’s sleep is important to weight control. Lack of sleep causes a hormonal imbalance, which can translate into cravings for high calorie foods and an increase in body fat.

How Genetics Affect Weight

Because of genes over three-quarters of a person’s body composition is pre-programmed at the time of conception. Researchers are finding that some people have a genetic tendency to be overweight or obese. It seems that such people are less sensitive to the signals their bodies give off when they are full. As a result they keep eating–much more than they need to.

Medical researchers have identified genes that increase and decrease appetite.  They have also found that genes play a major role in a person’s metabolism. The rate at which the body converts nutrients into energy can vary as much as 20 percent from person to person.

People with a genetic predisposition to overweight typically cannot lose weight through standard diets and exercise.

Weight Gain: A Complex Topic

Medical researchers, dieticians, and nutritionists continue to study what causes weight gain. A lot is known about this important subject, but there is a lot we still do not understand.