Obesity & Trauma

What is Obesity? Some Basic Understandings

Obesity is a dysregulated production of adipose tissue commonly known as fat throughout the body. It is considered a complex and chronic disease, which means there are multiple factors that contribute to its aestology (source). Additionally, it means that various biological systems are involved in its initiation and progression (source).

BMI

BMI is still the prominent technique for diagnosing obesity. It is the body weight in kilograms divided by the height in metres squared. The problem with BMI is it does not give insights or knowledge on the biological functions that contribute to the disease. Secondly, it does not measure the overall fat or its distribution. Despite these failings, BMI is still the main strategy for obesity diagnosis. (source) (source 1)

Obesity as a Risk Factor

Obesity can be a risk factor to cardiovascular disease, insulin resistance and type 2 diabetes, stroke, and Cushing’s syndrome, depression, and dementia. (source)

More Than a Weight Problem

Obesity can cause low-grade chronic inflammation through increased circulating fatty acids, and chemoattraction of immune cells that contribute to the inflammatory condition. 

Inflammation when it is working within a normal range, helps sustain the function of tissues and organs. It is also a protective response to an injury, infection, or irritation (source)(source). 

However, when it is chronic it can dysregulate various body functions. This is a core component of what makes obesity complex and a risk for other diseases. (source) (source)(source)

Obesity & Microbiome

There is increasing evidence indicating that gut bacteria plays a role in intestinal function, nutrient synthesis, and insulin regulation. 

Additionally, gut bacteria has been linked to chronic low level inflammation, which creates systemic exposure to bacteria ipopolysaccharide derived from the intestinal microbiota.

Interestingly, trauma or acute stress exposure have  been linked to changes in our gut environment. (source) (source) (source) (source)

What is Trauma and Why it is Important to Obesity

In psychology, trauma can be defined as the reaction to a deeply distressing or disturbing experience. In medicine, trauma is defined as a physical injury. Although the experience of trauma as described by these fields may at first seem discrete, they are largely intertwined. As well as the fact that they often co-occur, physical and psychological trauma are bi-directionally related perpetuates of the other. For example, the experience of a physical injury often triggers a psychological response and the experience of psychological trauma triggers a physical innate immune response. Accordingly, “the future might thus yield insights into multiple common and interactive immune responses, including immuno-metabolic and neuro-immunological switches and checkpoints after physical and psychological trauma (source).” 

Common examples of trauma experiences include physical and sexual abuse, verbal or emotional abuse, childhood neglect, intimate partner violence, accidents or disasters, illness, incarceration etc. Further, there are several ways in which these traumatic events are experienced (e.g. see source, source). These include the direct experience of single (acute trauma) or multiple (repetitive trauma) traumatic events either as an adult or as a child (developmental trauma). Further, trauma can be experienced through close individuals (vicarious), particular groups or populations (historical trauma, collective trauma) as well as generations (intergenerational trauma). 

Trauma also creates systemic biological and cellular changes. For example, it can change our gut bacteria environment, which has implications for obesity (source). In cases of acute trauma, some can experience PTSD, which creates neurobiological abnormalities which alters the function of various biological systems, this too has implications for obesity (source). The link between obesity and trauma also provides a wide ecological scope to understand the different determinants of a disease that is complex and not just a “lifestyle choice”. 

Systemic Trauma & Structural Violence

Trauma can come from direct pathways as described in the section above, however it can also be systemic. Norwegian sociologist, Johan Gultang, introduced the term structural violence in the 1960’s to describe the outputs of racism, classism, sexism, and other marginalisations (source). He defined structural violence as an “avoidable impairment of fundamental human needs” (source). For this report we are identifying the following systemic trauma pathways, we understand there are more, however this table illustrates there are various trauma based determinants for obesity.

Stress, Trauma, and Obesity

We have seen how trauma is both physical and biological. Further examination of the biological cascades that precede and follow the experience of stress and trauma provide insight into some of the pathways which facilitate and maintain the increasingly apparent relationship between trauma and obesity. For example, as can be seen in Figure 1, the consequences of trauma exposure and subsequent chronic stress include dysregulation of glutamate transmission, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and pro-inflammatory processes - all of which have been associated with obesity.

Inflammation, for example, is our body’s ability to protect against infection. However, its dysregulation (that is the alteration of its original function) has fundamentally changed our view of the underlying causes and progression of obesity and metabolic syndrome.

We now know that an inflammatory program is activated early in adipose expansion and during chronic obesity, permanently skewing the immune system to a proinflammatory phenotype, and we are beginning to delineate the reciprocal influence of obesity and inflammation. Reviews in this series examine the activation of the innate and adaptive immune system in obesity; inflammation within diabetic islets, brain, liver, gut, and muscle; the role of inflammation in fibrosis and angiogenesis; the factors that contribute to the initiation of inflammation; and therapeutic approaches to modulate inflammation in the context of obesity and metabolic syndrome.

Another trauma/obesity biological pathway is through the dysregulation of the HPA-Axis and its associated hormones that are essential in the distribution and breakdown of body fat (source). An example of how this pathway can play out can be seen in Figure 3.

Understanding these perturbations in obesity is particularly important given that dysregulation of the HPA-Axis is a risk factor for physical health conditions such as cardiovascular disease, insulin resistance and type 2 diabetes, stroke, and Cushing’s syndrome. 

These examples provide a demonstration of some of the ways in which trauma is associated with obesity. It is, however, important to note that this association is not linear, nor is it simple. Although a comprehensive model of the complex and multifaceted interaction between trauma and obesity (as well as the risk/protective factors for experiencing them) is beyond the scope of this report, Figure 2. Provides insight into the trauma / obesity cycle. It also highlights how structural violence pathways have a biological component.

An important observation is that trauma and obesity are bi-directionally related through pathways involving the disruption of psychological and biological systems. Further, Figure 3. shows that the experience of obesity and trauma play into a feedback loop.

These relationships begin to elucidate not just the formation, but the maintenance, of the trauma obesity association.

Childhood Obesity: A London case study

Obesity can lead to other equally complex diseases, therefore understanding obesity in the context of childhood is paramount in reducing later life diseases. Obesity is being diagnosed at younger and younger ages, which given what we have learned in this report, raises a question of morality. What type of society do we want, one of healing or one of chronic health injustice?

The objective of this analysis was to understand the relevant trends and comorbidities of places with high environmental stress factors, psychosocial stress factors, and the prevalence of severe childhood obesity - all of which are trauma determinants. This trend analysis is meant to complement the work done in identifying local and individual relationships between these different outcomes that can’t be captured in macro data.

The obesity data is based on surveys and is used as a sample to represent the obesity prevalence on a local authority level.

City of London data is joined with Newham in this data. Additionally, Reception data unavailable for: Enfield, Newham, Sutton, Wandsworth. Year 6 data unavailable for: Enfield, Wandsworth. These omissions are visible in the respective maps.

Severe obesity prevalence in reception (aged 4-5) children, London 2019-2020, by ward.

Severe obesity prevalence in year 6 (aged 10-11) children, London 2019-2020, by ward.

Top left map is Index of mass deprivation by ward and top right is the Biological Inequity Index (environmental stressors and IMD combined. Bottom left is year six obesity map and bottom right reception age obesity map. All at ward level.