Prescription Meds Often Overlooked Cause of Weight Gain

Prescription meds are often an overlooked cause of weight gain. Sometimes the side effects from one medication outweigh any benefits.  Weight gain is one of the most common side effects caused by many medications. One of the most important reasons to have your metabolic and weight problems treated by an endocrinologist or internist is that they are the medical professionals best trained to recognize that certain prescriptions can cause weight gain and to adjust your prescription medications accordingly.

Because of interference in metabolism, increased hunger, or increased cravings, weight loss can become almost impossible with some of these prescription medications.  This is one of the most common and least recognized causes of weight problems. They are often overlooked by patients and prescribing physicians alike!

10 Reasons Prescription Medications Can Cause Weight Gain

Weight gain and difficulty losing weight due to prescription medications can have many causes. Since weight gain and difficulty with weight loss are so common, the secret is knowing which drugs may cause weight gain and why.

Here are some of the reasons prescription medications can cause weight gain:

• Metabolism: Energy consumption is reduced—this is a metabolism issue. This is seen with drugs such as Paxil, Zyprexia
• Insulin: Increased insulin secretion leads to increased fat tissue.
• Appetite is increased.
• Thirst is increased, which is often quenched with sugary drinks.
• Water retention is increased.
• Cravings increase: makes us want to eat more, especially salty and sweet foods.
• Increased acid secretion in the stomach may increase appetite.
• Increased appetite but not real hunger—important to differentiate.
  
• Fatigue and less activity leading to lower metabolism.
  

Increased Appetite vs. Increased Hunger

Learning to distinguish between increased hunger and increased appetite may help differentiate drug-induced weight gain from other causes. Hunger is when you must eat immediately and just about any food will satisfy you. Appetite is when you feel like eating but without the urgency of hunger.

Most medication-induced weight gain is due to an increase in appetite. It causes a nagging feeling that you want to eat more but won’t really make you hungry. A good test of the difference between hunger and appetite is whether you are willing to eat something you really don’t like that much. If the answer is yes, you are hungry. If the answer is no, then it is your appetite calling to you.

We know that serotonin, the chemical in the brain that regulates mood, also regulates appetite. Antidepressants work only on the mood function of serotonin and may in some way interfere with the appetite function.

Common Medications Causing Weight Gain:

Estrogen and progesterone hormone treatment

These drugs, together or by themselves, increase appetite, cause water retention, and, at high doses, also increase blood sugar and fat mass. The male hormone testosterone may also increase appetite.

Corticosteroids (e.g. cortisone) are a very common cause of weight gain

These increase our appetite and induce excessively high levels of insulin in our blood (hyperinsulinemia), which cause our bodies to store fat. The longer the treatment and the higher the dose, the more the weight gain. Most of the weight gain is around the abdomen – as high as 30 lbs. Locally injectable corticosteroids, such as those used in the knee joint or spinal column to treat inflammation, and inhaled corticosteroids used for asthma are not associated with weight gain. Steroids can affect the metabolic rate, leading to increased appetite and overeating.

Examples of corticosteroids include prednisone, methylprednisolone, and hydrocortisone.

Migraine medication often causes unexplained weight gain

Migraine medications cause weight gain in 70% of the patients who take them. Amitriptyline and Nortriptyline are examples.

Cancer treatments: less common cause

Some chemotherapy or hormone therapy protocols used to treat breast cancer are the reason why most of these patients gain weight.

High blood pressure (hypertension) – beta-blockers are a very common cause of weight gain

They can cause weight gain by blocking fat burning through inhibition of sympathetic tone. These prescription medications are used to prevent heart failure and treat high blood pressure. Common examples of this class are metoprolol (Lopressor) and atenolol (Tenormin). Many of the older beta-blocker drugs can lead to fatigue, which is responsible for some of the weight gain. Patients are tired, low on energy, and generally fatigued. This reduces daily activity and calories burned.

Antibiotics: may cause weight gain, but not important because they are rarely taken long enough to cause a problem

Antibiotics are widely used in industrial livestock breeding to fatten cattle. They increase livestock weight gain by 10%. They have exactly the same effect on the human body. However, it’s usually too rare over long enough periods to cause weight gain.

Anxiety and Depression Drugs (Psychotropics): Most common cause of severe weight gain— often taken over a long time (years instead of days)

Used to treat nervous disorders, these prescription medications act in that area of our brain (the hypothalamus), which controls our appetite and regulates body weight. Likewise, some antidepressants, neuroleptics, tranquilizers, and tricyclic antidepressants also increase our appetite, lead to snacking, and furthermore stimulate insulin secretion. Why antipsychotics cause weight gain is uncertain, but people who use antipsychotics have been shown to have higher levels of an enzyme in the brain called AMP-kinase that can block the H1 histamine receptor and, like antihistamines, boost appetite. Many of these drugs also interfere with blood sugar control, leading to insulin resistance and type 2 diabetes. The blockade of the serotonin receptor 5-HT2C also appears to contribute to excess weight gain. Psychotropic prescription medications causing weight gain include:

• citalopram (Celexa)
• fluoxetine (Prozac)
• fluvoxamine (Luvox)
• mirtazapine (Remeron)
• paroxetine (Paxil)
• sertraline (Zoloft)

Lithium, which is used to treat behavior disorders such as bipolar disorder, interferes with normal thyroid function. Therefore, it makes people gain weight.

Anti-diabetes medications -a known cause in diabetics

Sulfonylurea medications cause weight gain (approximately 10 to 20 pounds during the first 4 to 12 months). This weight gain manifests as an increase in body fat. The cause is increased insulin secretion, leading to excessive water retention. Examples of these prescription medications also include glyburide (DiaBeta) and glipizide (Glucotrol). These agents may increase insulin production, which can lower blood sugar levels and increase appetite.

Insulin itself can also lead to weight gain. This is possibly due to periods of low blood sugar that stimulate appetite and conversion of sugar to fat. Other drugs used in the treatment of type 2 diabetes can lead to weight gain and fluid retention. Examples include pioglitazone (Actos) and rosiglitazone (Avandia), which are in the class thiazolidinediones. Others include:

• glimepiride (Amaryl)
• glipizide (Glucotrol)
• glyburide (Diabeta, Micronase)
• nateglinide (Starlix)
• pioglitazone (Actos)
• repaglinide (Prandin)

Metformin (Glucophage), exenatide (Byetta), and sitagliptin (Januvia) are more likely  weight neutral or associated with weight loss.

Seizures/Mood Stabilizers

Valproic acid (Depakote, Depakene) is used to treat epilepsy (seizures) and bipolar disorder, as  as migraine prevention. Valproic acid appears to increase appetite and may result in a weight gain of 10 pounds or more. Lithium (Lithobid) is also used for mood disorders and is associated with weight gain. Other mood stabilizers causing weight gain include:

• clozapine (Clozaril)
• lithium (Eskalith, Lithobid)
• olanzapine (Zyprexa)
• quetiapine (Seroquel)
• risperidone (Risperdal)

Antihistamines: slight weight gain, uncommon

An estimated 50 million people in America suffer from hay fever and other allergies. However, if they take antihistamines, such as cetirizine (Zyrtec) and fexofenadine (Allegra), they are more likely to be overweight and have higher insulin concentrations. According to a 2010 study, people on antihistamines weighed 4 to 6 lb more than those not taking them. These drugs react with the H1 histamine receptor, which, besides its role in allergies, is part of the brain’s appetite-center chemicals. Suppression of this receptor’s activity can stimulate the appetite. Other antihistamines causing weight gain include:

• diphenhydramine (Benadryl)
• loratadine (Claritin)

Metformin and Topiramate Reduce Medication-Induced Weight Gain

Recent reports show that these two drugs cause weight gain from many medications, especially the psychotropic ones.

Summary of Prescription Drugs and Weight Gain

This often-overlooked problem should be reviewed whenever weight loss is unusually slow, or there is a sudden weight gain. Look for drugs taken for longer periods of time (months rather than days). That is where the problem will be found. Antihistamines, hormones, diabetic medication, and especially anxiety and depression medications account for most of the significant problems. Once found, the goal is to find similar medication without this side effect.

Table 1: Medications Causing Weight Gain