It is not a coincidence that the U.S. suffered from one of the highest amounts of Covid deaths in the world. We are also one of the most obese countries in the world and now that we have had almost 2.5 years of data from the pandemic, the relationship is very clear: The most significant risk factors for severe disease or death, aside from advanced age, are obesity and the associated co-morbidities such as diabetes, hypertension and lung disease.
How does excessive weight impact the immune system? Overweight and obese individuals have excess amounts of body fat, and it is fat cells that make inflammatory proteins such as TNF-α, IL-6, IL-1β, IL-18, and MCP-1. Fat cells also make other compounds, such as leptin and adiponectin, that have a modulating effect on overall immune function.
Although the mechanism is not completely understood, it is believed that having a higher than normal level of these compounds continually circulating can desensitize the immune system, so when an actual infection occurs the immune system is less prepared to respond. In addition, overweight and obese individuals are likely to have lower levels of vitamin D and more oxidative stress – both of which can negatively impact normal immune health.
When researchers study the impact of obesity on immune function, respiratory illness is a consistent area of concern. For example, we know that excess body fat increases the risk for contracting the flu (influenza), as well as being hospitalized, requiring intensive care, acquiring a secondary infection such as bacterial pneumonia, and death.
Moreover, obesity is associated with decreased vaccine efficacy. With the flu vaccine, for example, obese individuals experience a more rapid decline of antibody levels and have an altered response compared to non-obese individuals, which results in overall weaker immunity. An additional challenge is that it is often harder to provide advanced respiratory support in higher-weight individuals because intubation can be more difficult.
Unfortunately, the Covid virus and variations/mutations are here to stay, Monkey Pox has entered our lives and the flu virus has and always will be present. There has never been a better time to boost our immune systems. This starts with successful weight control.