Obesity Watch

Use of Chronic Beta-Blocker Therapy Associated with Obesity

Long-term use of beta-blocker therapy may be associated with an increased risk of obesity, according to an Australian study published online in February 2011 in the International Journal of Obesity.

The scientists enrolled 30 volunteers and 298 patients from diabetes and hypertension outpatient clinics, and analyzed data from the large, multicenter type 2 diabetes trial ADVANCE, which enrolled 11,140 patients. In addition to energy expenditure via diet-induced thermogenesis, fat oxidation rate, weekly habitual activity, body weight, body mass index, and waist circumference were also recorded in the analyses.

Among weight-matched beta-blocker users, energy expenditure via diet, fat oxidation, and habitual activity were much lower compared with controls. Additionally, patients treated with beta-blockers had a significantly higher adjusted mean body weight than controls in the outpatient clinics and the ADVANCE trial.

The findings suggest the concerning idea that patients who receive beta-blockers, who have a higher sympathetic blockade and theoretically less energy expenditure, may be at increased risk of being overweight or obese. Because of the pharmacologic effect they may have on the nervous system, beta-blockers may decrease habitual activity by decreasing exercise capacity, which may also contribute to weight gain.

Once the gold standard for treating hypertension, beta-blockers are no longer the recommended first-line agents. However, they are used quite frequently and effectively in patients with heart disease and should not be discontinued due to the possibility of gaining weight. Instead, Dr. Paul Lee, the lead author of the study, suggests patients who are on beta-blocker therapy should be “extra mindful” of their weight and seek additional guidance from nutritional experts. PT

Early Menarche Independent of Maternal BMI

Researchers from the UCLA School of Public Health studied the in utero effect, if any, an increased body mass index (BMI) in mothers has on the age of menarche in daughters. Although it is known that an increased pre-pubertal BMI is associated with earlier age of menarche, it is unknown whether maternal BMI has any influence in utero.

The cohort study, published online ahead of print in Fertility and Sterility, consisted of 2 parts. Between 1984 and 1987, 13,815 pregnant women from 2 Danish cities were recruited to be included in the study, and a questionnaire was administered assessing for health and lifestyle as well as height and weight. In 2005, 3169 girls living in Denmark who were born to women in the study completed a survey on age of menarche. Multiple linear regression analyses were conducted to examine the association between maternal pre-pregnancy BMI and age of menarche. The researchers found that when mutually adjusted, maternal BMI had little effect on the age of menarche, whereas offspring BMI had a large effect that was independent of maternal BMI.

The authors state that the longitudinal design is unique to this study, and that other studies were heavily limited by recall bias. Although the study refutes the association between maternal obesity and younger age of menarche, it does not disprove the theory that maternal obesity may have other negative consequences in offspring. More studies are needed in this unique patient population.

Ear Infections Associated with Pediatric Obesity

Can otitis media be linked to childhood obesity? Researchers from Kyung Hee University in South Korea published a prospective, case-controlled study in the March 2011 issue of Archives of Otolaryngology Head and Neck Surgery that enrolled 42 children with chronic otitis media with effusion and 42 children without. Taste threshold was measured with electrogustometry and 4 chemical taste tests, and body mass index (BMI) was recorded.

The scientists found that BMI was significantly higher in patients with chronic otitis media with effusion than in patients without (20.6 kg versus 17.7 kg, P = .02), and the taste thresholds were significantly higher in patients with chronic otitis media with effusion than in patients without at the anterior left (P = .03) and right (P = .04) tongue. A reduced capacity for taste is associated with an excessive intake of calories and fluids, which may lead to obesity. This change in taste, particularly in this location of the tongue, the authors note, is associated with the chorda tympani nerve, which may deteriorate due to inflammation of the middle ear.

When they compared the taste thresholds with the chemical taste tests, the scientists found that those with chronic otitis media with effusion had a significantly lower taste threshold for sweet and salty tastes than controls (P = .02 for sweet; P = .04 for salty), taste thresholds important in biological nutrition. Although the sample size was very small, the researchers were able to conclude that children with chronic otitis media do have changes in their sense of taste, which may be related to childhood obesity.