Is there an obesity epidemic?
At the time Holbein’s portrait of Henry VIII was painted, carrying weight showed wealth and status. Today, we recognise that excess weight contributes to health problems. But what is obesity, and is there really an obesity epidemic? Heart Matters investigates.
Talking about obesity can be tricky, because the general public’s perception of it often differs from that of healthcare professionals. Paul Aveyard, Professor of Behavioural Medicine at Oxford University, explains: “This is a problem because when we talk about obesity and its risks on the news, in TV programmes or even in Heart Matters, many people assume those risks apply only to the extremely overweight. In fact, they apply to most of us.”
Am I overweight?
Health experts use body mass index (BMI), which is a measure of weight adjusted for height, to assess whether someone is a normal weight, overweight or obese.
You can calculate your body mass index (BMI) by dividing your weight in kilograms by your height in metres squared. A BMI of above 25 may mean you are overweight. If it is over 30, you may be obese.
The exception is for people of South Asian descent, who are at increased risk of cardiovascular disease at a lower BMI than the rest of the population. This means the healthy BMI range for South Asian people is narrower; a BMI over 23 would be viewed as overweight, and a BMI of over 27.5 as obese.
Understanding the health risks of being overweight
Excess adipose (fatty) tissue upsets our metabolic processes, puts up blood pressure and worsens our blood cholesterol pattern, which make cardiovascular disease more likely. It also affects the way our body deals with glucose, the main sugar we use as fuel for our cells. This can cause type 2 diabetes, a major risk factor for cardiovascular disease.
Most people with a BMI of above 30 have too much adipose tissue in their body, but not all. “BMI is an imperfect measure of health risk. It is an approximate measure of a damaging level of body fatness,” says Professor Aveyard.
Is obesity a problem?
There are two ways to answer this question, “depending on whether we look at individuals or societies”, says Professor Aveyard. For individuals, excess fatty tissue has always been a problem because it causes high blood pressure, high cholesterol and diabetes, and is one of the main causes of cardiovascular disease.
In societies like ours, where many people are obese, it has become a major problem. “It’s not just that there are more obese people in 2015 than there were in 1980. It’s as if we’ve all had a few kilograms of fat added to our bodies,” says Professor Aveyard.
In England, we have had good records of the prevalence of obesity since 1980. Then, it was relatively rare, with six per cent of men and eight per cent of women classed as obese.
Two decades later, in 2001, those rates had tripled. In the UK, obesity rates are rising faster than in the rest of Europe, as revealed in the 2004 Health Select Committee Report on obesity, which also linked 8.7 per cent of all UK deaths to excess weight.
If we don’t act, more than half of all UK adults and a quarter of all children will be obese by 2050, according to Foresight Report.
Lately, the rise in prevalence of obesity has slowed and the latest projection is not as dire, but it is still predicted that 40 per cent of adults will be obese by 2030. The direct healthcare costs linked to excess weight and obesity has reached an estimated £4.2bn, and the total cost to the UK economy around £16bn.
If we don't act, more than a quarter of all UK children will be obese by 2050
Can we stop the obesity epidemic?
Governments, the NHS and other health organisations are working together to help stem the tide. In 2013, the UK Department of Health released a policy stating its intention to reduce obesity levels by 2020. But we all have a part to play by eating a balanced diet and getting regular physical activity.
Professor Aveyard says: “Shedding a kilogram of excess adipose tissue does your health as much good if you are only a little overweight, as it does if you are grossly overweight, or obese. The risks from a kilo of extra fat are the same, regardless of how many other kilos you are carrying.”