Recent advances. Weight management

Today’s illustration is the Willendorf Venus, about 25,000 BCE and the oldest known representation of the human form – obesity is not a new problem!

Over the past three or so years, the research literature has been dominated by Covid 19, its epidemiology, its effects, its management. Now, however, Covid has been replaced by Obesity. This has been driven partly by the increasing prevalence of overweight and obesity and partly by the emergence of effective drugs for weight management. For the next few weeks I will report some of the results of research in this field and what is being written by experts and others.

Definition of obesity

Let’s start with trying to define overweight and obesity. The usual measure is Body Mass Index (BMI) which is weight in kilograms divided by height in centimetres squared. No-one wants to work that out but Dr Google will do it for you. Search for BMI and any number of sites come up. Choose one and feed in your height and weight in any units you choose and up comes the figure. Ideal weight lies between 18 and 25, overweight between 25 and 30, obesity between 30 and 40 and morbid obesity anything over 40.

BMI is not perfect but better than any other single measure. There are arguments for using waist circumference or ratio of waist to height or skin fold thickness. Any of these can be used to enhance the significance of BMI but on their own cannot replace BMI.

Body fat content can be measured directly by DEXA scanning.  A paper presented at The Endocrine Annual Meeting suggested than using this technique showed that BMI “Vastly underestimates” true obesity. Studies of 10,000 US adults using DEXA scanning rated 74% as obese compared with 36% using BMI (1). Unfortunately DEXA scanning is neither cheap nor convenient. An alternative is measurement of “bio-impedance” which uses a small electric current to assess adiposity and can be incorporated into bathroom scales. I look forward to seeing how this pans out over the next few years.

Epidemiology of obesity

Epidemiology is defined as the scientific study and analysis of the distribution, pattern, and determinants of health, and disease conditions in a defined population and the application of that study to control the disease in the population. Put simply this means the study of how often diseases occur in different groups of people and why. Its main aim is to identify the risk of a disease and to target preventive measures.

Disease or lifestyle choice?

The medical community is divided. Here are two quotes:
1. “Obesity is a serious chronic, progressive and relapsing disease”
2. “Obesity is a matter of personal responsibility but public health officials are far too nervous about saying so”
My preferred position is to sit on the fence.
To support point 1, the obese do have a distinct psycho/physiological problem and this is a reduced perception of satiety – they are unable to sense when they have eaten enough. Both genetic factors and early life experience contribute.
To support point 2, obese people are able to lose weight, though it is more difficult for them than it would have been for lean individuals. This is important because if the obese believe that being fat is a disease they are less likely to think that they can do anything about it.

Frequency

High and increasing. For example in the UK about 30% of the population is obese and this is predicted to rise to 21 million people (36% of the population) by 2040 (2). This is found across the world and more than half the world’s population is predicted to be overweight or obese by 2035.

Distribution

Obesity is far more common in poorer areas – the King’s Fund found the prevalence of obesity to be 37% in poor areas compared with 19% in rich areas. In England the prevalence of obesity is highest in the North East and West Midlands (34% of adults) and was lowest in the South East (24%) and London (23%).

The prevalence of obesity tends to be higher in richer countries across Europe, North America, and Oceania. Obesity rates are much lower across South Asia and Sub-Saharan Africa. More than one-in-three (36%) of adults in the United States were obese in 2016. In India this share was around 10 times lower (3.9%).

Costs

Obesity has been estimated to cost the NHS £6.1 billion a year and the Treasury about £58 billion.  These are probably gross underestimates. A study at Imperial College has found that obese patients cost twice as much as those of a healthy weight. – £1,375 versus £638 per annum. This means that if everyone was of healthy weight the NHS could save £14bn a year.

Consequences

Obesity may or may not be a disease but it is certainly risk factor for all sots of other conditions. The inexorable rise in obesity has seen a sixfold rise in cases of Type 2 Diabetes (T2DM) over the past five decades. Obesity also contributes to heart attacks, strokes, several types of cancer, lower limb arthritis and ultimately to frailty in later life.

Next time I will start to address the management of this dangerous condition.

1. ENDO 2023. Abstract OR10-01. June 2023.
2. BMJ 2022;377:o1265