Obesity and physical and emotional well-being: associations between body mass index, chronic illness, and the physical and mental components of the SF-36 questionnaire.

OBJECTIVE: To clarify the associations between obesity and health-related quality of life by exploring the associations between physical and emotional well-being in relation to obesity and the presence of other chronic illness. RESEARCH METHODS AND PROCEDURES: The study data were collected as part of a postal-survey within the old Oxford Regional Health Authority of England in 1997. Completed questionnaires were returned by 8889 of 13,800 randomly selected adults aged 18 to 64 years. The main outcome measures were body mass index in five categories (underweight, normal weight, overweight, moderately obese, morbidly obese); chronic illness status (any vs. none and number of such illnesses 0, 1 to 2, 3+); and mean SF-36 questionnaire score in two summary component measures reflecting physical and emotional well-being.
RESULTS: Of the subjects, 31% were overweight and an additional 11% were obese. Body mass index was significantly associated with health status, but the pattern varied according to whether the measure reflected physical or emotional well-being. Physical, but not emotional, well-being deteriorated markedly with increasing degree of overweight and was limited in subjects who were obese but had no other chronic condition; subjects with chronic illnesses other than obesity were compromised in both dimensions. In terms of the number of chronic illnesses reported, the additional presence of obesity was associated with a significant deterioration in physical but not emotional well-being. DISCUSSION: Overweight and obesity are associated with poor levels of subjective health status, particularly in terms of physical well-being. The limitations in emotional well-being that are reported here and in other studies may be a result of confounding by the presence of accompanying chronic illness.