BMI and quality of life - Obesity - Body mass index

Nutrition Research Newsletter, Feb, 2004

Obesity is a major public health problem due to its increasing prevalence and its associations with higher morbidity and mortality from multiple diseases. Many cross-sectional studies have also documented that obesity is related to impaired physical functioning, one aspect of health-related quality of life (HRQoL). However, previous findings on obesity and social well-being and mental health--two other aspects of HRQol--have been inconsistent.

Currently, approximately 7% of the world population is older than 65, and it is projected to rise to 12% by 2030--and it is expected to rise from 12% to 20% in the United States. In this era of population aging, the quality of life of older adults is particularly important at both the societal and individual levels. Therefore a recent study in Obesity Research investigated the relationship between BMI with health-related quality of life in adults 65 years and older.

In 1996, a health survey was mailed to all surviving subjects > 65 years old from the Chicago Heart Association Detection Project in Industry Study (1967 to 1973). The response rate was 60% and the sample included 3981 males and 3099 females. BMI was classified into four groups: underweight (<18.5), normal weight (18.5 to 24.9), overweight (25 to 29.9), and obese (>30). The 12-item Health Status Questionnaire (HSQ-12) was used to measure HRQoL in eight domains: health perception, physical functioning, role limitations (physical), bodily pain, energy/fatigue, social functioning, role limitations (mental), and mental health. The higher the score, the better the outcome.

In general, there was an inverse association between BMI and age, education, smoking and alcohol intake among women. Similar patterns were observed for men except for alcohol. Adjustments having been made for age, race, education, smoking and alcohol intake, obesity was associated with lower health perception and poorer physical and social functioning (women only) but not impaired mental health. Overweight was associated with impaired physical well-being among women only. Both underweight men and women reported impairment in physical, social and mental well-being. Compared with normal-weight persons, obese men and women had a higher prevalence of most chronic diseases. For seven of eight items form the HSQ-12, obese and underweight women had a higher prevalence of adverse conditions compared with normal-weight women.

Both underweight and obese older adults reported an impaired quality of life, compared with normal weight people--particularly worse physical functioning and physical well-being. These results reinforce the importance of normal body weight in older age. One interesting finding was the significant association between overweight and poor physical functioning among women, but not among men. One explanation is that the healthy BMI range for men may be different from that for women. More in-depth studies on potential gender differentials and on weight changes over time are needed.

Lijing L. Yah, Martha L. Daviglus, Kiang Liu, et al. BMI and health-related quality of life in adults 65 years and older. Obesity Research 12(1): 76 (January 2004) [Correspondence: Dr. Lijing L. Yah, Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, 680 North Lake Shore Drive, Suite 1102, Chicago, IL 60611-4402. E-mail: lijing@northwestern.edu.]