Obesity and Mortality: Association Varies By Age, Gender

Tapan Mehta, Ph.D. Assistant Professor School of Health Professions University of Alabama at BirminghamMedicalResearch.com: Interview with
Tapan Mehta, Ph.D.
Assistant Professor
School of Health Professions
University of Alabama at Birmingham


MedicalResearch: What are the main findings of the study?

Dr. Mehta: Grade 1 obesity’s (body mass index [BMI] 30 to < 35) association with reduced longevity has lessened over calendar time for older white men (age >60) but not for younger middle aged (age ≤60) men. For white women, there is evidence of a decline in the association of obesity, both for Grade 1 obesity and grade 2-3 obesity (BMI ≥35), with reduced longevity across all adult ages.

To the extent that these associations can be taken as indicators of causation, this implies that the harmfulness of obesity-mortality association has declined over calendar time in white women across all ages. However, the decline in the harmfulness of obesity-mortality association is limited to older grade 1 obese white men.

MedicalResearch: Were any of the findings unexpected?

Dr. Mehta: Overall, the results seem to suggest that while obesity-mortality association may have become less deleterious over calendar time for white women across ages, this trend does not hold for younger and middle-aged white men. This was somewhat surprising finding especially since:

  • One of the possible and plausible explanations for the reduction in the harmfulness of obesity-mortality association is improvements in medicine and screening procedures over calendar time
  • Existing gender gaps in medical care and treatment between men and women.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Mehta: This is a population-level study that informs policy makers, funders and medical community about the trend in the obesity-mortality association over calendar time. This study informs clinicians and patients that:

  • a) The reduction in deleteriousness of obesity-mortality association varies by gender and the grade of obesity.
  • Although there has been a decline in the harmfulness of obesity-mortality association in some groups, obesity especially grade 2-3 obesity continues to remain associated with reduced longevity in younger and middle-aged white men and women.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Mehta: Our findings suggest but not prove that advances in medicine, screening procedures and interventions may have reduced the excess mortality associated with overweight and grade 1 obesity. There are other explanations possible as well for the decline. Recommendations for future studies:

  • Research needs to be done to directly evaluate some of these explanations/hypotheses. For example identifying and evaluating which treatments have reduced the association of obesity-mortality at the population level would help us identify and focus on strategies that seem to be working.
  • Our rigorous methodological framework can be applied to evaluate similar questions such as whether the excess mortality associated with other cardiometabolic conditions has changed over calendar time.
  • As more longitudinal data on minorities becomes available we will be able to evaluate these scientific questions using our rigorous study design and methods.
  • The role and trends in gender gaps and disparities in medical care is also an interesting aspect that can be studied to further build upon this work.Citation:

Mehta, T., Fontaine, K. R., Keith, S. W., Bangalore, S. S., de los Campos, G., Bartolucci, A., Pajewski, N. M. and Allison, D. B. (2014), Obesity and mortality: are the risks declining? Evidence from multiple prospective studies in the United States. Obesity Reviews. doi: 10.1111/obr.12191