Certain Medications Can Cause Weight Gain

By Michel Montignac

There are certain prescription drugs that can cause us to gain weight or, in the best of cases, inhibit our body’s ability to lose weight.

This is basically due to the fact that:

  • They reduce the amount of energy we burn up;

  • They increase fat tissue by stimulating insulin secretion;

  • They increase our appetite;

  • They make us thirsty that which might make us seek to quench out thirst with sugary drinks;

  • They increase water retention ;

  • They alter our taste buds and might thus make us to want to eat more.

Some medications can even bring about a combination of several of these weight-gaining mechanisms.

Hormone treatments (estrogen-progestin therapy)

Increase our appetite and cause water retention.  In high doses, estrogens and progesterone can, by way of higher blood sugar levels, even induce increases in body-fat mass.

Corticoids (cortisone)

Increase our appetite and induce overly high levels of insulin in our blood (hyperinsulinism) which cause our bodies to store fat. The probability of gaining weight is even greater in the case of long-term treatments. 

Migraine pills

Cause weight gain in 70% of the patients who take them.

Cancer treatments

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), namely beta blockers

Are generally prescribed to prevent heart failure, reduce high blood pressure and tackle migraine headaches.

They can cause weight gain since they lower food thermogenesis (burning of fat) by inhibiting sympathetic tonus. In some cases, they also increase water retention.


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 and become an even greater weight risk factor when taken for extended periods.


Used to treat nervous disorders, these drugs act on that area of our brain (the hypothalamus) which controls our appetite and regulates body weight.

Likewise, some anti-depressants, neuroleptics, tranquilizers and tricyclic antidepressants, also increase our appetite, lead to snaking and furthermore stimulate insulin secretion.

Lithium, which is used to treat behavior disorders such as maniac psychotic depression, interferes with normal thyroid functions thus making us gain weight.

Antidiabetes medications

Sulfa hypoglycemic medications almost systematically cause weight gain (approximately 10 pounds during the first 3 to 12 months). This weight gain chiefly affects body-fat mass and is basically due to the insulin-secretion stimulation effect and, collaterally, to excessive water retention.


It is, to say the least, paradoxical that those medications prescribed for the treatment of certain pathologies such as hypertension and diabetes should, by causing weight gain, end up aggravating the risk factors already developed by this diseases.

This is precisely why doctors should take this weight-gaining factor into account when prescribing medication for these illnesses.

It is important to note that not all medications which fall into the same therapeutic category necessarily have the same side effects.

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