Obese people report sexual problems such as lack of desire, lack of enjoyment, avoiding sex and performance difficulty at a much higher rate than people of normal weight - in some cases, they are 25 times more likely to report problems, according to the Duke study. Overall, women experienced more difficulties than men among both weight groups, but the gender differences were small compared to the disparity between the obese and normal weight study populations.
"Our study shows a striking difference in sexual quality of life between obese and normal weight people. Sexual quality of life is an important issue for everyone, and with the growing prevalence of obesity in this country, increasing numbers of people will likely be affected," said study co-investigator Martin Binks, Ph.D., a clinical psychologist and director of behavioral health at the Duke Diet & Fitness Center.
The results were presented Nov. 15, 2004, at the annual meeting of The North American Association for the Study of Obesity in Las Vegas. Funding was provided by the Duke Diet & Fitness Center, a residential treatment program for obesity that emphasizes lifestyle change, physical activity and healthful eating.
Co-investigator Ronette Kolotkin, Ph.D., a clinical psychologist with experience treating obese patients, said losing weight and increasing physical activity can help restore sexual quality of life for people with obesity-related problems.
"My patients tell me that losing a little weight and getting fit makes them feel 10 to 20 years younger in terms of their sexual quality of life," she said. Kolotkin developed the 31-item study questionnaire, called Impact of Weight on Quality of Life-Lite, which evaluates all aspects of weight-related quality of life.
More than 1,200 study participants answered questions about their general sexual quality of life, as well as four, more specific sexual topics: lack of enjoyment of sexual activity; lack of sexual desire; difficulty with sexual performance; and avoidance of sexual encounters.
Almost two-thirds (65.4 percent) of obese people seeking treatment at the Duke Diet & Fitness Center reported sexual impairments in at least one of these four areas, compared to five percent of normal weight people. The Duke researchers also questioned obese people who were not seeking weight loss treatment; 41 percent said they experienced sexual impairment.
Of the 1,210 study participants, 506 obese people seeking treatment were drawn from the Duke Diet & Fitness Center; 422 obese and 282 normal weight people who weren't seeking to lose weight were recruited from the community. The average body mass index (BMI) of the obese groups was 41 for the treatment seekers and 40 for the non-treatment seekers. BMI is a measurement of body fat based on height and weight, and obesity is defined as a BMI of 30 or greater. The normal weight group had an average BMI of 22.
The average age of the groups was 48 for treatment seekers; 45 for non-treatment seekers; and 35 for normal weight people. The balance between men and women varied between the groups. About 53 percent of the obese treatment seekers were women, rising to 67 percent in the obese non-treatment group and 71 percent in the normal weight group.
The most significant differences were between normal weight people and obese people seeking treatment at the Duke Diet & Fitness Center. Only 2 percent of the normal weight group reported sometimes, usually or always feeling no desire for sex, compared to 50 percent of obese treatment seekers. Additionally, 42 percent said they sometimes, usually or always had sexual function problems and 41 percent said they avoided sex; the responses were 1.8 percent and 2.5 percent, respectively, in the normal weight group.
The group of obese people who weren't seeking to lose weight didn't experience sexual quality of life issues as frequently as people at the Duke Diet & Fitness Center, however, the rates in this group were significantly higher than for normal weight persons. About 29 percent said they sometimes, usually or always felt no desire for sex or had problems with sexual function, and 24 percent said they avoided sex. But the response was nearly equal in one category - 28 percent of treatment seekers and 30 percent of non-treatment seekers said they sometimes, usually or always did not enjoy sex, compared to 3.9 percent of normal weight people.