Published: 03-11-2022 17:43 | Updated: 10-11-2022 15:29

New thesis explores the association between BMI and health outcomes in old age

Two elderly people cycling in nature, they are both wearing helmets.
Photo: Franz W/Pixabay CC0

Hi there, Jie Guo, PhD student at the Division of Aging Research Center (ARC), Department of Neurobiology, Care Sciences and Society at Karolinska Institutet! You will defend your thesis entitled "Unraveling the relationship between body mass index and cardiometabolic disease, dementia, and survival in old age" on 10 November 2022. What is the main focus?

Portrait picture of Jie Guo
Jie Guo, PhD student at ARC/NVS. Photo: Chenxi Qin

Overweight and obesity, commonly defined as a body mass index (BMI) ≥25 kg/m2, affect more than half of older adults. However, the association between BMI and health outcomes in old age is unclear. My PhD project aims to describe the trajectories of BMI as well as other anthropometric measures in old age. Additionally, I explore the associations between short- and long-term changes in BMI with cardiometabolic diseases (CMDs), dementia, and survival, highlighting modifiable factors that could modify such associations. 

What are the most important results?

BMI, together with two muscle mass proxies (i.e., calf circumference and mid-arm circumference), declines over time in older adults. Cardiometabolic disorders can accelerate the rate of these declines, whereas high educational attainment and physical activity appeared to decelerate them.

Overweight/obesity in mid or late life is associated with an increased risk of CMDs. A favorable lifestyle could partly mitigate the impact of overweight/obesity on CMDs.

Both large BMI loss and large BMI gain are related to an increased risk of dementia. Moreover, both mid- and late-life overweight/obesity may shorten chronic disease-free survival among older adults. 

How can this new knowledge contribute to the improvement of older people's health?

The thesis provides a more comprehensive understanding of patterns of BMI trajectory among older adults. It expands previous studies by investigating the health risk of weight change and long-term BMI change patterns.

These findings suggest that mid and late-life high BMI and substantial BMI changes can predict adverse health outcomes in old age. Among older adults, keeping a normal and primarily stable BMI can help to prevent detrimental health outcomes and extend a healthy lifespan.

What are your future plans? Will you keep on conducting research?

Yes, I will continue researching healthy aging, and my goal is to help older adults living better and longer.


Jie Guo Affiliated to Research