As an endocrinologist, I am very familiar with the type of people who are most at risk from COVID-19. They’re usually older, usually overweight, and are stricken with the accumulated damage of decades of metabolic dysfunction: Type 2 diabetes, hypertension, heart disease.
Over the years I’ve helped hundreds of patients lose weight, drop their medications, and improve their quality of life, primarily through diet and lifestyle adjustments.
Now I’ve come to believe those same exact adjustments may be the best way we have of readying our bodies to fight off the coronavirus. The overlap between poor metabolic health and vulnerability to COVID-19 has become impossible to ignore.
Metabolic Health and Resilience
Lately I’ve been exchanging notes with a mentor of mine who is on the true front lines of the crisis. He’s a senior doctor in a hospital in New York City, which is now one of the world epicenters of the pandemic. He’s seen dozens of COVID-19 deaths already, a number that will only continue to grow. So many of his regular patients are dying – men, mostly, with obesity, diabetes, hypertension, kidney disease – that in a low moment, he told me “I am not sure who I will treat next year.”
He runs tests on new COVID-positive patients upon admission – lactate dehydrogenase count, neutrophil to lymphocyte ratio – biomarkers that reveal the damage that the disease has already inflicted. It can be shockingly easy to know which new patients will live or die. Those with good numbers will survive, and those with bad numbers will not.
It’s the people in the middle who are more difficult to predict, and the ones for whom the absence or presence of these underlying conditions seems so important: “No diabetes mellitus or hypertension, they’re doing well. With obesity, not so much. This virus will wipe out many obese diabetics.”
The data and the anecdotes, whether from China or Italy or the United States, all say the same thing: people who are in poor metabolic health are especially at risk of severe COVID-19 outcomes. So why aren’t we talking about how to improve metabolic health as a way to protect ourselves?
Insulin Resistance & the Immune System
It’s been frustrating reading media accounts of the significance of co-morbidities to COVID-19 outcomes. Cardiovascular disease, hypertension and diabetes are spoken of as if they were independent components. Obesity is ignored or downplayed as a factor. In reality, these conditions are intertwined, and are linked by a single underlying condition: insulin resistance.
Insulin resistance is the biggest risk factor for cardiovascular disease. It is a primary factor in the development of hypertension. We’ve known these facts since the 1980’s, but in the rush to blame saturated fats and dietary cholesterol, most doctors ignored them. Type 2 diabetes is essentially just a symptom of an extreme level of insulin resistance.
We are only just beginning to guess why insulin resistance allows the novel coronavirus to be so damaging. We know that insulin resistance leads to chronic inflammation, and that it otherwise impairs our immune response in myriad ways. In the insulin resistant body, fat cells are overstuffed, and they spill fat into the bloodstream. Fat accumulates in our lymph, thymus and bone marrow important tissues of the immune system. The fat alters the activity and distribution of leukocytes, lymphocytes and T-cells, significantly weakening our immune response. Leptin resistance, adiponectin deficiency and low HDL-cholesterol, all associated with obesity and insulin resistance, also inhibit the immune system in diverse ways.
High blood sugar, a common symptom of insulin resistance and the hallmark of Type 2 diabetes, impairs the immune system in many other ways. The link between diabetes and COVID-19 is already well-established, and people with diabetes were at much higher risk of death in the previous SARS and MERS coronavirus epidemics.
How do We Optimize Metabolic Health to Boost Immunity?
There’s no quick fix or magic pill, but a smart diet and a few lifestyle changes can improve your metabolic health in a short period of time.
The evidence is clear that a low-carbohydrate or ketogenic diet can be an effective tool. The modern Western diet, defined by its overreliance on simple carbs, highly processed foods, refined oils and junk foods, may be the single biggest contributor to the global scourge of obesity and its associated metabolic disorders. Swapping these unhealthy foods for choices high in protein and healthy fats, such as meats, and dark green vegetables, may be the best way to increase insulin sensitivity. Your microbiome, another key to a healthy immune system, will likely benefit too.
Exercise, even just a moderate amount of it, can have extraordinary results. A sedentary lifestyle has long been associated with metabolic harm, and it is well-established that exercise boosts the immune system and reverses insulin resistance.
Sleep is likewise a very important regulator of immunological processes. Many studies have shown that volunteers with even mild sleep deprivation are significantly more likely to get ill from the cold or flu compared to those getting full nights of rest. Chronic stress can also create “persistent and severe” immune system deficiencies. I recommend that you do what you can to reduce the stressors in your life.
I cannot say for certain that the immune system dysfunction observed in obesity and insulin resistance is responsible for the increased risk of complications and death in COVID-19. Nor can I say that having perfect blood sugars definitively reduces those risks. The disease is too new to understand its mechanisms yet. And, clearly, there are other risk factors mostly unrelated to insulin resistance, such as old age and poor pulmonary health.
But what I do believe is that the best way to actively combat COVID-19 – aside from the critical hygiene and social distancing measures that health experts have already urged us to adopt – is to do everything you can to improve your metabolic health.
