Obesity among adults in the United States has been increasing since the 1980s, with the trend continuing during the past 20 years, according to Craig M. Hales, MD, MPH, MS. In the National Health and Nutrition Examination Survey (NHANES) 2017-2018, the incidence of obesity (BMI ≥30 kg/m2) among adults aged 20 and older was 42.4%, and the incidence of class 3 obesity (BMI ≥40 kg/m2) was 9.2%. “Although the high prevalence of obesity can be tied to greater calorie intake and lower energy expenditure, other factors such as medication use may also play a role,” he says.

Weight gain, Dr. Hales explained, is a negative and unintended effect of many prescription medications, or “obesogenic” medications. The use of obesogenic medications reduces weight loss that occurs as part of weight loss programs and following laparoscopic sleeve gastrectomy.” In NHANES 2011-2012, more than one-half (51%) of US adults used a prescription medication, and 15% used five or more prescription medications. Yet, the frequency of the use of obesogenic prescription medications is unknown,” he says.

One in Five US Adults Take Obesogenic Medications

For a study published in Obesity, Dr. Hales and colleagues aimed to assess trends in the use of obesogenic prescription medications among US adults from 1999 to 2018, both overall and by therapeutic class. “We also wanted to see if there is a relationship between obesity and use of obesogenic prescription medications for each therapeutic class,” he adds. “Finally, we wanted to know the most frequent reasons for taking obesogenic medications.”

The researchers examined cross-sectional data on adults aged 20 and older from the 1999-2018 NHANES (N=52,340). Obesogenic medications were characterized according to 2015 Endocrine Society guidelines on the pharmacological management of obesity. Weight status was classified according to BMI.

“We found that in 2017 – 2018, one in five US adults took a medication that can cause weight gain,” Dr. Hales says. “Beta-blockers and anti-diabetics were the most common obesogenic medications used. The most common reasons for taking an obesogenic medication were disorders of glucose metabolism, hypertension, neuralgia or neuritis, heart disease, and musculoskeletal pain and/or inflammation.”

 Medications Use Increased Along With Weight Status

The study team also found that use of obesogenic medications rose with increasing weight status. “However, use of any medication also increased with increasing weight status,” Dr. Hales points out. “Because of this, obesogenic medication use as a percentage of total medication use within the therapeutic class was not associated with obesity. The exception to this was for antipsychotics, where the proportion of obesogenic antipsychotics use relative to total antipsychotic use grew with increasing weight status. (Figure).”

Obesity is a risk factor for several conditions that can be managed with obesogenic medications, which, in turn, may lead to further weight gain, Dr. Hales and colleagues concur. “The choice to prescribe a non-obesogenic alternative, if possible, is guided by weighing the risks and benefits of available treatments,” he says.

The study has some limitations, Dr. Hales notes, the most important one being that there is no agreed-upon list of obesogenic medications. “Different systematic reviews of obesogenic medications have led to differences in which medications are considered obesogenic,” he says. “In the interest of consistency with current recommendations, this study relied only on the 2015 Endocrine Society guidelines, though some interpretation of the text was still necessary for classification of individual obesogenic medications. Therefore, standardized measurement and reporting of the effects of medications on weight and a continually updated consensus lists of obesogenic medications would improve the quality of monitoring obesogenic medication use.”