NEW YORK (Reuters Health) – In a small study of overweight and obese adults, 3 months of aerobic exercise, with no change in diet, led to a significant decrease in body fat and a spontaneous decrease in caloric intake. The percentage of weight loss and the reduction in caloric intake correlated positively and significantly with concentrations of brain-derived neurotrophic factor (BDNF).

“The reduction in caloric intake could be related to the effect of BDNF in appetite regulation,” Dr. Henry Anhalt of the Animas Corporation, West Chester, Pennsylvania told the Endocrine Society’s 90th annual meeting in San Francisco.

“It is possible that the increases in this compound in fact suppress appetite; however, this was not directly tested,” added Dr. Anhalt, who moderated a press conference where the study was reported.

In the study, Dr. A. Veronica Araya and colleagues from University of Chile Clinical Hospital in Santiago evaluated blood levels of BDNF before and after 3 months of aerobic exercise in 15 overweight or obese men and women. The 7 men and 8 women, ages 26 to 51 years, exercised on a treadmill and bicycle.

At the end of the 3-month exercise period, study subjects experienced a significant decrease in BMI (from 30.6 to 30.1; p = 0.01), waist circumference (from 108.1 to 105.1 cm; p = 0.003) and percentage body fat (35.2 to 33.3%; p = 0.0029).

They also experienced a fall in systolic blood pressure (128.7 to 122.6 mmHg; p = 0.05) and diastolic blood pressure (82.3 to 72.6 mmHg; (p = 0.007), and spontaneously consumed fewer calories each day (2142 to 1805 cal; p = 0.01).

Serum BDNF rose from 2.4 ng/mL before exercise to 7.8 ng/mL after exercise (p = 0.001), and “the concentration of BDNF was correlated positively with the percentage of weight loss to a fairly high degree,” Dr. Anhalt reported for Dr. Araya, who was unable to attend the press conference where the findings were released.

In a statement issued through the Endocrine Society, Dr. Araya said: “It is important to clarify the factors involved in the response to different weight loss therapies, because we could find a marker to predict response to the intervention.”