Know whether you're obese or not: Simple ways to calculate your body mass index (BMI)
Knowing is easy, and it's the first step in doing something about it
The world is going through a period of unprecedented abundance. Think of one metric: life expectancy. In the last 200 years, life expectancy increased globally from less than 30 years to over 72 years.
It’s still rising — more and more people live past 80, 90, and even 100.
Good news, bad news
That’s the good news. Now, the bad news. There’s a whole lot — the pandemic, wars, terror and random violence — they grab eyeballs, by capitalising on man’s “fight-or-flight” instinct.
Still, we’re much better off today than, say, the last century. Whether it's about access to clean water, medical services or information, things at your disposal allow you and I to live more than twice as long as our ancestors did, according to Our World in Data.
Amid this abundance, however, there's one cause for pessimism: the so-called obesity epidemic.
Obesity: a silent epidemic
It’s one downside of abundance. Look at the numbers: Worldwide obesity has nearly tripled since 1975. As of 2000, the number of obese adults has increased to over 300 million.
In 2016, more than 1.9 billion adults, 18 years and older, were overweight or pre-obese, according to WHO data.
In terms of gender: 1 in 5 women and 1 in 7 men will be living with obesity within the next 7 years, according to the atlas.
Death from obesity
Obesity or being overweight is seen behind 2.8 million deaths each year, according to WHO data. The condition also leads to adverse effects on blood pressure, cholesterol, triglycerides and insulin resistance.
In short, higher risks of coronary heart disease, stroke and type 2 diabetes mellitus come with increasing BMI.
What causes obesity?
Obesity is primarily caused by eating too much and moving too little, says the UK’s National Health Service. Consuming high amounts of energy-giving foods — particularly fat and sugars (carbohydrates) — but do not burning them off through physical activity, results in surplus energy being stored by the body as fat.
Due to their rather limited means, our ancestors never had the chance to indulge in carb overconsumption.
How does high BMI worsen outcomes from COVID-19?
Data from the US Centres for Disease Control and Prevention (CDC) show COVID-related death rates go up with increasing BMI. In general, people who are overweight have up to three time the risk of hospitalisation following COVID-19 infection, according to the agency.
High BMI also affects your sleep
Moreover, having a higher-than-average BMI may also have a harmful effect on your sleep. Dr Hassan Al Hariri, Head of Sleep Clinic and Pulmonologist, Rashid Hospital, says that weight-related issues are one of the key reasons for sleep disorders such as sleep apnoea.
This “relaxation” causes an obstruction at the back of your throat. When your brain recognises the lack of oxygen, you wake up frequently to stretch those muscles. Some patients, take a big snore, which occurs when they transition from deep to light sleep.
How obesity triggers hyperventilation syndrome
Obesity hyperventilation syndrome (OHS) is condition that affects people with a BMI higher than 35. It’s similar to sleep apnoea but sufferers have high levels of carbon monoxide in their bloodstream.
“When you breathe, you breathe in oxygen and exhale carbon monoxide. Your body needs to keep the carbon monoxide levels at around 40 in your blood,” says Dr Hariri. “If you’re obese and, due to your weight, you are not taking deep breaths, carbon monoxide will start accumulating in your blood. OHS occurs when you are not breathing adequately to remove the toxins from your body.”
How to measure BMI
In the medical profession, BMI scores break down as follows:
BMI under 18.5 = underweight
BMI 18.5 to <25 = healthy
BMI 25 to <30 = overweight
BMI 30 to <35 = obese (class 1)
BMI 35 to <40 = obese (class 2)
BMI 40 or higher = obese (class 3 - morbid)
BMI is not a perfect measure
Sometimes it can give a "false positive" score — especially to athletic individuals, whose high BMIs are due not to excess body fat, but to excess muscle.
What is waist-to-height ratio (WHtR)?
Compared to simple BMI, the waist-to-height ratio (WHtR) compares the circumference of a person's waist to their height. If the waist is more than half the height — or more than 6/10 the height for those over 50 — that person is obese.
WHtR is considered much more accurate than BMI, but is also much newer. Many medical experts suggest switching from BMI to WHtR.
Over time, WHtR could then replace BMI as the “de facto” measure of a person's weight health.
Whether we use BMI or WHtR, these are valuable indicators of where we all stand at the moment. A 2017 survey shows most parents don’t know their children’s BMI. Learning is the first step — toward willing to do something about it.