Obesity as a Risk Factor of Disease
Written by Vicky Diep
Edited by Priya Ram
March 21, 2022
Edited by Priya Ram
March 21, 2022
We often hear about the rising rates of obesity around the world as being a cause for alarm due to obesity’s correlation with many chronic health conditions, such as diabetes, cardiovascular disease, stroke and even some types of cancer (NIDDK, 2016). This rise in obesity is often referred to as the “obesity epidemic” of the 21st century. Public health efforts to redefine obesity as a disease are commendable in making the public aware of the importance of physical exercise and carefully managing one’s diet to prevent obesity and its associated risks (Kyle et al., 2016). However, it can be argued that the label of disease has done little to reduce the stigma surrounding obesity. Individuals are often unfairly blamed for their health. Rather than viewing obesity itself as a disease, it may help to view it as a risk factor of disease - one that can be prevented by exercise and a healthy diet, but also possible therapies that target its mechanism of causing disease. Let’s see why by diving into the cellular level and looking at one of the proposed mechanisms for why obesity is a risk factor for disease, particularly diabetes.
It turns out that chronic tissue inflammation is a major hallmark of obesity (Rohm et al., 2022). The inflammatory response in tissues is part of the body's immune defense against infectious agents such as bacteria and viruses. It is mediated by substances called cytokines, which are released by immune cells, including macrophages. In the adipose tissue of obese individuals, there are higher numbers of macrophages, and thus higher concentrations of inflammatory cytokines (Rohm et al., 2022). These cytokines are believed to facilitate glucose absorption into immune cells but suppress glucose absorption into other cells by making the latter temporarily resistant to insulin, the hormone that serves as a signal for cells to absorb glucose from the blood. This is an adaptive mechanism to ensure that enough resources are diverted to immune cells which need the energy to fight bacteria and viruses during times of infection. However, chronic inflammation and suppressed glucose absorption by cells leads to insulin resistance and hyperglycemia (high blood glucose), which is the cause of Type 2 diabetes, the more prevalent of the two types of diabetes. When cells become resistant to insulin, they become unable to take in glucose for energy, and the body’s beta cells try to compensate by producing more insulin until they experience failure.
Recognizing the link between immune and metabolic dysfunction has led to research and development in anti-inflammatory drugs that target cytokines responsible for chronic tissue inflammation. This includes an antagonist for the inflammatory cytokine IL1-ꞵ, which is effective in reducing beta cell failure and hyperglycemia (two defining characteristics of Type 2 diabetes), as well as cardiovascular complications (Rohm et al., 2022). As we can see, understanding the mechanism behind a disease often helps elucidate possible treatment options for it. Understanding the mechanism behind why obesity is a risk factor that underlies so many chronic diseases will hopefully also normalize it as a health condition and reduce the stigma historically ascribed to it.
References
Kyle, T. K., Dhurandhar, E. J., & Allison, D. B. (2016, September). Regarding obesity as a disease:
Evolving policies and their implications. Endocrinology and metabolism clinics of North
America. Retrieved February 1, 2022, from
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988332/
Rohm, T. V., Meier, D. T., Olefsky, J. M., & Donath, M. Y. (2022). Inflammation in obesity, diabetes, and related disorders. Immunity, 55(1), 31–55. https://doi.org/10.1016/j.immuni.2021.12.013
U.S. Department of Health and Human Services. (2016). What is diabetes? National Institute of Diabetes and Digestive and Kidney Diseases. Retrieved January 30, 2022, from https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes