ORLANDO — African American women in general lose less weight after gastric bypass surgery than do white women, but the reasons are unknown. A recent study found that diet, eating behavior, and psychosocial status do not explain the disparity, but changes in fat mass seem to be the key.
“We know that African American women are generally more obese overall,” Cynthia K. Buffington, Ph.D., said in an interview at a poster presentation during the annual meeting of the American Society for Bariatric Surgery.
Dr. Buffington and her associates compared morbidly obese African American and white women with no significant differences in preoperative body mass index, ideal body weight, or fat mass.
The study included 39 African American women with a mean BMI of 51 kg/m
Investigators also compared 39 of the African Americans to a subgroup of 39 whites matched for preoperative weight (a mean 143 kg). One year later, the African American women lost 62% of their excess weight to a mean of 94 kg, whereas the white women lost 80% of excess weight to a mean of 78 kg.
In the full cohort, the investigators determined psychosocial status using the Minnesota Multiphasic Personality Inventory-2 and the Millon Behavioral Medicine Diagnostic instruments. African American women had fewer psychosocial issues than did white women in the study, perhaps because obesity is more culturally accepted in the African American community, Dr. Buffington said.
“African American women are more self-confident and have fewer psychosocial issues related to their obesity,” said Dr. Buffington, director of research at U.S. Bariatric in Fort Lauderdale, Fla.
Specifically, African American women demonstrated significantly less depression, emotional instability, introversion, inhibition, and feelings of isolation or dejection; fewer adjustment problems; and better social adjustment than did white women in the study.
Dr. Buffington and her associates assessed patient diet histories and scores on eating-behavior questionnaires.
The reserchers found no significant differences in macronutrient intake or eating behaviors such as binge eating, food cravings, or eating control to explain the reduced effectiveness of surgery in African Americans.
“Both groups were consuming large amounts of calories, but there were no differences in carbohydrates or proteins,” Dr. Buffington said.
“Both were consuming high amounts of fat, but there were no differences between groups.”
African Americans had a 47% change in fat mass 1 year after surgery that was far less than the 63% change for whites, Dr. Buffington said. “This was strongly correlated to total weight loss.”
“We think it means there is a biological basis for surgery not to induce as much fat loss in a morbidly obese population of African Americans versus [whites],” Dr. Buffington said. She said other investigators are finding reduced oxidation of fat in the muscle of African American females.