BMI and Coronavirus

I received a text from my doctors surgery this week asking for my weight and height. No further explanation, except they were updating their records and would be grateful if I could supply the information.  Could this be anything to do with Boris Johnson’s announcement to take a more “interventionist” approach to tackling obesity in the UK? It’s been reported that Boris believed his condition became more serious because of his weight.  As time has gone on, it has become increasingly evident that obesity is linked to poorer outcomes for those who are infected with the coronavirus.  A questionnaire sent out to 166 hospitals in the UK found that patients that were obese had a 33% greater risk of dying than those that were not.

Writing about obesity is always difficult. People are overweight for different reasons, and often these are far-reaching and complex in nature. However, obesity impacts one in every four people in the UK and one of the adverse effects of this is a disruption in the function of the immune system.  This places the body under a constant level of stress which then makes it harder for your body to fight infection.

So what is BMI?

BMI (Body Mass Index), is a measure to judge overall weight calculated by taking your weight in kilos and dividing them by the square of your height in metres.  A healthy weight is a BMI between 18.5 and 24.9 according to the NHS.  Anything between 25 and 29.9 is considered ‘overweight’ and 30 plus is ‘obese’.

Is BMI the best measurement of Obesity?

It’s quick and easy and works for some, but not all.  It can be misleading.  If you carry a lot of muscle on your body like body builders, rugby players etc. your weight can be high in relation to your height and therefore give you a BMI that suggests you are unhealthy when in fact you are extremely fit and healthy.

That’s why, when I work with clients I focus on body measurements and overall percentage of body fat to track progress.  Research shows that people who carry a lot of fat around their waists are at higher risk of health problems than those that are more pear shaped with fat carried around their thighs and bottoms.  They are more likely to have visceral fat stored in their abdomen around key organs, which could increase the risk of heart disease, stroke and type 2 diabetes.

Boosting our immune system with exercise

So we all know that we can manage our weight by eating healthily and taking more exercise, but did you know exercise is a powerful tool for boosting your immune system? In the journal of sport and Health Science David Nieman DrPH conducted a study looking at the effects of regular walking on the immune system and found that exercise can improve your immune response, lower illness risk, and reduce inflammation.  Because exercise increases blood and lymph flow as your muscles contract, it also increases the circulation of immune cells, making them roam the body at a higher rate and at higher numbers. Specifically, exercise helps to recruit highly specialised immune cells that find pathogens (like viruses) and wipe them out. In Nieman’s 2019 review, participants who took a 45-minute brisk walk experienced this increase of immune cells floating around the body for up to three hours after the walk.