Body mass index and subjective well-being in young adults: a twin population study

Milla S Linna,Aila Rissanen,Jaakko Kaprio,Elina Sihvola,Anu Raevuori,Anna Keski-Rahkonen

doi:10.1186/1471-2458-13-231

Abstract

BackgroundBody mass index (BMI) is associated with subjective well-being. Higher BMI is believed to be related with lower well-being. However, the association may not be linear. Therefore, we investigated whether a nonlinear (U-shaped) trend would better describe this relationship, and whether eating disorders might account for the association in young adults.MethodsFinnTwin16 study evaluated multiple measures of subjective well-being, including life satisfaction, General Health Questionnaire (GHQ-20), satisfaction with leisure time, work, and family relationships, and satisfaction with sex life in young adulthood in the 1975–79 birth cohorts of Finnish twins (n=5240). We studied the relationship between indicators of subjective well-being and BMI both in full birth cohorts and in subgroups stratified by lifetime DSM-IV eating disorders.ResultsWe found an inverse U-shaped relationship between all indicators of subjective well-being and BMI in men. There was no overall association between BMI and subjective well-being in women. However, there was an inverse U-shaped relationship between BMI and indicators of subjective well-being in women with a lifetime eating disorder and their healthy female co-twins. Subjective well-being was optimal in the overweight category.ConclusionsBoth underweight and obesity are associated with impaired subjective well-being in young men. The BMI reflecting optimal subjective well-being of young men may be higher than currently recognized. Categorization of body weight in terms of BMI may need to be reassessed in young men. BMI and subjective well-being are related in women with a lifetime eating disorder, but not in the general population of young women.

Highlights

Body mass index (BMI) is associated with subjective well-being
Obesity was relatively rare among these young adults, as approximately 4% of both men and women were obese (BMI ≥30 kg/m2)
In our study, we found an inverse U-shaped relationship between BMI and subjective well-being in men

Summary

Introduction

Body mass index (BMI) is associated with subjective well-being. We investigated whether a nonlinear (U-shaped) trend would better describe this relationship, and whether eating disorders might account for the association in young adults. Body mass index (BMI) is associated with both physical and psychological health, including overall mortality, chronic somatic illnesses [1] as well as psychiatric disorders [2,3]. While the link between obesity and impaired quality of life and lowered subjective well-being has been well documented [3,9,10,11,12,13], less is known about the relationship between subjective well-being and underweight. Low subjective well-being is related to low satisfaction in various life domains and high levels of psychological distress [14]. To untangle the effects of eating disorders, we conducted stratified analyses among women with a lifetime eating disorder, their unaffected twin-sisters (representing those with a genetic susceptibility to eating disorders), and women who had neither had an eating disorder nor had a sister with an eating 32 healthy female co-twins of women with a lifetime disorder

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Discussion

Conclusion