EXERCISE AND BODY WEIGHT

Eat less – the gates of paradise are narrow
AJ Cronin

Non Communicable Diseases (NCDs) and risk factors

Now I would like to talk about all those NCDs and their risk factors which are impacted by exercise or lack of it. In most cases exercise is able not only to prevent these conditions but also to treat them. It is not always clear what is a disease and what is a risk factor. This weeks condition, obesity, is a good example. Some hold it as a disease while others strongly disagree – they see it as a lifestyle choice. I will discuss the  controversy on another occasion.

The definition of overweight and obesity – assessing weight

The standard way of assessing weight is by comparing it with height to give the Body Mass Index (BMI). The BMI is the weight in kilograms divided by the height in metres squared. So a 70kg (about 11 stone) person who is 1.75m (about 5 foot 9ins) tall has a BMI of 70 divided by 1.75 squared  which is 70 divided by 3.0625 which comes to about 22.9. You do not need to work out your own BMI so laboriously. Just Google “BMI” and there are plenty of websites which will work it out for you using either pounds and feet or kilograms and centimetres.
The ideal BMI is generally accepted as between 18.5 and 25. Between 25 and 30 is “overweight”, between 30 and 40 is “obese” and over 40 is “morbidly obese”.

Weight distribution

For the purposes of measuring risk for most conditions, a BMI between 20 and 25 is optimal. Weights higher than this carry an increasing risk of coronary disease, type 2 diabetes and other conditions, of which much more later. However there is more to weight than BMI. It also matters where you store your excess fat. Obesity can be predominantly either central or peripheral. Those with central obesity store fat in the abdominal cavity and have paunches or beer bellies – the apple shape. Those with peripheral obesity store it on their hips, bums and thighs – the pear shape. Being an apple is much more dangerous than being a pear. So when it comes to assessing risk from obesity, mainly risk for cardiovascular diseases, waist measurement seems to give a better picture than BMI. The upper limit of recommended waist size for men is 102cm (40 ins) and for women 88cm (35 ins). With higher measurements the risk for cardiovascular disease, diabetes and high blood pressure all rise steeply.

History

Obesity is not a new condition. One of the oldest surviving human carvings, the Venus of Willendorf, created some 27,000 years ago, depicts a strikingly obese woman. Hippocrates in about 500 BC reported that obese people were at increased risk of sudden death and as long ago as 1727 a British physician wrote “No age has seen more instances of corpulency than our own”. To which the proper response might be “Man, you ain’t seen nothing yet!”

Obesity is a huge and growing problem in most Western countries and the figures published about its extent are as gross as the problem itself.  The weight of the average person in the UK has risen by more than 3lbs (1.5kg) every decade since 1970.  It has been estimated that the annual cost to the NHS associated with obesity is more than £47 bn. The horrifying statistics go on and on. The UK is the most overweight nation in Western Europe and our levels of obesity are growing faster than in the US.

Development

The seeds of obesity are sown in childhood. In reception year (aged 4-5) 9.5% of children are obese and by year 6 (10-11) this has risen to 19% and is still rising. The rate of severe obesity has risen from 3.2% to 4% in the last decade and the inexorable rise in childhood obesity is behind the very serious problem of rising levels of childhood type 2 diabetes.  Interventions in schools aimed at reducing levels of obesity have mostly been failures, which is not unrelated to the selling off of school playing fields. However, maternal lifestyle is also a  prominent contributor to the risk of obesity in the child.

There has been a marked increase in the proportion of adults in the UK who are obese, from 13.2% in 1993 to 26.0% in 2013 for men, and from 16.4% to 23.8% for women. The proportions that were overweight or obese increased from 57.6% to 67.1% in men and from 48.6% to 57.2% in women. Globally more than one billion adults are overweight of whom some 300 million are obese

The causes – too much food or too little exercise?

This huge increase in obesity would seem to be explained by the rise in availability of high calorie foods, particularly sweet, fizzy drinks and the widespread use by the food industry of high fructose corn syrup. Surprisingly, however, a team of economists from Holloway published a paper in 2016 showing that, judging by the sale of calorific foods, the average daily calorie intake of adults in the UK actually fell by 20% over the previous 30 years! They concluded that the rise in obesity was a result of “a decline in the strenuousness of work and daily life”. Their figures are supported by The Department for Food, Environment and Rural Affairs (DEFRA) which has shown that overall our calorie intake peaked in the 1970s, declined until the 2000s and have flattened since. More evidence coming to similar conclusions is provided by the food surveys conducted by Public Health England.

This view of the cause of our increasing obesity is not shared by all. The Obesity Health Alliance is firmly convinced that the causes are changes in diet, increasing portion size, far more meals eaten outside the home and a shift to ready meals, junk food and snacks. The whole problem is made more obtuse by the fact uncovered by the Office of National Statistics that the average Briton consumes 50% more calories than they estimate for themselves – so-called social desirability bias.  As one representative of the National Obesity Forum is quoted as saying “People lie and I am not surprised that they do when it comes to food. They wish not to be taken for slobs, even though they may be just that!”

The results

Obesity is much more than a medical problem. In 2015 in the UK the cost to the NHS directly attributable to obesity was £4.2 billion and the cost to the wider economy was £15.5 billion. And as we get fatter our perceptions change – the new norm is to be overweight or obese with the feedback consequence of the likelihood of an increasingly corpulent population.

Next week I will look at the medical consequences of being overweight or obese.