Dissertation
Selected health implications of low body mass: determinants and health outcomes
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2018
DOI: 10.17077/etd.wwtv-jd0c
Abstract
<p>While the role of obesity in health outcomes has been well described, the role of low body mass index (BMI), body weight relative to height, has largely been ignored. Those with low BMI are commonly excluded completely or combined with the normal BMI category in BMI studies. However, there have been some studies indicating poorer health outcomes among those with lower BMI, particularly that of increased risk of mortality. The purpose of this study is to explore the role of low BMI throughout the lifespan.</p>
<p>Data from the Health and Retirement Study was used to evaluate 1) the association between childhood health and socioeconomic status (SES) exposures and low BMI in midlife adulthood, 2) the association between low BMI and health related outcomes in midlife adulthood (ages 50 to 65), and 3) the association between low BMI in midlife and health related outcomes, including mortality, over a longer follow-up (maximum of 20 years). To increase sample size, two low BMI definitions were used: the traditional</p>
<p>Few significant results were found. Low BMI status was consistently associated with older age and female gender as well as current smoking status. Childhood exposure of respiratory disease and greater SES disadvantages was more common among those with low BMI in adulthood. In midlife adulthood, low BMI status was associated with increased difficulties with activities of daily living with either definition of low BMI. Increased risk of fracture was associated with a low BMI definition of <18.5. Increased risk of lung disease and decreased risk of high blood pressure was associated with a low BMI definition of ≤20. An analysis of those 30 years old or older found low BMI to be associated with increased risk of mortality and decreased risk of diabetes regardless of low BMI definition. When low BMI was defined as <18.5, those with low BMI were also more likely to experience difficulty with one or more activities of daily living. When low BMI was defined as ≤20, low BMI status was associated with greater risk of lung disease and decreased risk of high blood pressure.</p>
<p>Further research is needed to fully characterize the role of low BMI on health outcomes as well as the role of SES on low BMI. Additionally, there is a need for greater understanding of the potential biological mechanisms of low BMI for health outcomes. Currently, there are few studies evaluating health outcomes and SES of low BMI. Limiting studies to the extreme upper end of the BMI spectrum limits the overall understanding of the role of BMI in health and may overlook unique characteristics and challenges those with low BMI may face.</p>
Details
- Title: Subtitle
- Selected health implications of low body mass: determinants and health outcomes
- Creators
- Andrea Lee Holcombe - University of Iowa
- Contributors
- Robert Wallace (Advisor)James Torner (Committee Member)Wei Bao (Committee Member)Knute Carter (Committee Member)Barbara Baquero (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Epidemiology
- Date degree season
- Autumn 2018
- DOI
- 10.17077/etd.wwtv-jd0c
- Publisher
- University of Iowa
- Number of pages
- xi, 93 pages
- Copyright
- Copyright © 2018 Andrea Lee Holcombe
- Language
- English
- Date submitted
- 03/01/2019
- Description illustrations
- illustrations
- Description bibliographic
- Includes bibliographical references (pages 87-93).
- Public Abstract (ETD)
While obesity has been well established as a risk factor for a multitude of health conditions, the opposite extreme, low body mass index (BMI) (body weight relative to height), is much less studied. This study seeks to add to the literature and explore the role of low BMI throughout life, including whether exposures in childhood contribute to low BMI status in midlife and how low BMI may affect health in midlife and at older age. To evaluate this, two low BMI definitions were used: the traditional <18.5 and ≤20 based mortality risk graphs.
Few significant results were found in this study. Throughout life, female gender and older age was significantly associated with low BMI status. Childhood exposures such as respiratory diseases and socioeconomic disadvantage were associated with low BMI of ≤20. During midlife adulthood, low BMI was associated with increased risk of stroke and difficulty with physical function (activities of daily living). In longer follow-up through midlife to end of follow-up (up to 20 years), low BMI was associated with increased risk of lung disease, difficulty with physical function (activities of daily living), and mortality, as well as decreased risk of diabetes and high blood pressure.
While this study did not have sufficient power to fully explore the role of low BMI, there is some indication that those with low BMI may experience greater health risks than those with normal BMI. Larger studies are needed with the ability to evaluate this relationship more in-depth.
- Academic Unit
- Epidemiology
- Record Identifier
- 9983777235302771
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