Published Wed, 2010-11-17 15:33; updated 34 weeks ago.
Is obesity a new problem?
“I believe no age did ever afford more instances of corpulency than our own.”
Thomas Short, A Discourse Concerning the Causes and Effects of Corpulency. 1727.
“Obesity has reached epidemic proportions globally, with more than 1 billion adults overweight - at least 300 million of them clinically obese.”
World Health Organisation 2003.
Today's messages about obesity suggest it is a problem for our modern age?
A problem linked to 21st century lifestyles, use of cars, digital technology and fast food? Well think again.
The two statements above, published centuries apart, show that the current problem of rising rates of obesity is not new.
“Survival of the fittest” once dictated that those who could store energy from their diet would survive the inevitable periods of scarcity.
"However, as our diets have become richer in energy and our daily lives more sedentary, those of us who have inherited this legacy - storing excess amounts of fat, particularly around the abdomen - have become increasingly likely to be victims of early deaths. This gradual shift began centuries ago."
Evidence of obesity can be dated back to the Old Stone Age.
The Venus of Willendorf, a carved figurine depicting a woman with marked abdominal obesity, is estimated to be 23,000 – 25,000 years old.
Ancient Egyptian Stone reliefs show obese people.
In Egyptian society diet was recognised as a means of preserving health.
So if there have been obese individuals for millennia, when were the consequences of Obesity recognised?
Although in some eras and in some cultures, people considered obesity to be a sign of affluence and wellbeing, the consequences of obesity in terms of associated illnesses and reduced life expectancy were recognised early on.
Not all of these associations were first noted in the modern era.
In 500-400 BC Hindu physicians recognised that black ants were attracted to the sugary taste of diabetic urine and noted the disease often affected inactive, overweight people.
Hippocrates, the “Father of Medicine” (460-370 BC) recognised that “sudden death is more common in those who are naturally fat than in the lean.”
In the 4th century BC Dionysius, an obese man himself, was an early sufferer of Obstructive Sleep Apnoea.
Fearing suffocation at night, he employed attendants to wake him at regular intervals by pricking him with needles.
George Cheyne (1671-1740), a doctor who weighed 32 stone at his peak, wrote of the associated depression, skin disorders and circulatory problems.
Much of the current research centres on the distribution of fat within the body and the important metabolic consequences of central, or abdominal, fat deposits. Even this finding is not new.
In 1765 Morgagni was the first to note the differing patterns of fat deposition in his post mortem dissections of obese subjects.
In 1811 Robert Thomas recognised that central distribution of fat occurred more often in diabetic people.
Life insurance data from 1901 show that excess weight, especially around the abdomen, was associated with a shorter life expectancy.
In 1947 Jean Vague defined the android (apple) and gynoid (pear) shaped physiques we are now familiar with and clearly established the importance of central obesity in conferring excess mortality.
How have measurements of obesity changed?
In some respects, the answer to this is “surprisingly little”.
The Belgian statistician Adolphe Quetelet (1796 – 1874) developed the “Quetelet Index,” later renamed the Body Mass Index (BMI).
BMI is still used today as a marker of obesity, showing some relationship with body fat content and some ability to predict obesity related illnesses.
The BMI scale is not perfect. For instance, many international rugby players, whilst very healthy, would register as overweight or obese on the BMI scale.
On the contrary, it is possible to be unfit with a “healthy” BMI reading and yet have an unhealthily high proportion of body fat.
The scale also cannot account for the distribution of the fat deposits.
Doctors now commonly use simple measures of abdominal obesity such as waist circumference or the ratio of waist:hip circumference in clinical practice and research to assess levels of abdominal obesity.
In some cases these measures can be better predictors of later obesity-related ill health than BMI.
Current research uses ultrasound, CT (computed tomography), MRI (magnetic resonance imaging), DEXA (Dual energy Xray absorptiometry) scans and body volume measurement continues to refine the measurement of body fat content and distribution in order to increase our understanding of the consequences of obesity.
In the twentieth century, as techniques to measure basal metabolic rate developed, it emerged that most obese people have normal or higher than average rates of metabolism.
These studies underpin modern dieting advice, demonstrating that very rapid changes in weight on dietary programmes are due to changes in the amount of body water rather than fat reduction.
Studies in the 1920s demonstrated a fact known to many frustrated dieters: If calorie consumption is very low then people may not lose weight - the body enters “starvation mode” and conserves all the energy it can.
The 1970s saw the development of physiological techniques which defined the effects of obesity on metabolism and “insulin resistance”.
Although these associations had previously been described the metabolic mechanisms behind them were becoming increasingly clear.
Breakthroughs in the study of genes relevant to obesity and metabolism have identified signalling pathways which are important in appetite and weight control.
Although this has increased our understanding of the systems regulating appetite and weight, abnormalities in these genes account for only a minority of cases of obesity and none are currently likely to lead to any targets for treatment for most overweight people.
The situation today
Along the way there have been some diversions and dead ends.
In 1760 some, such as Flemyng, wrongly attributed the cause of obesity to “an abnormal state of the blood” or to “defective evacuation”.
The Egyptians used treatments such as binging and purging to reduce excess weight.
Such remedies would not be recommended today.
Despite these diversions the progress toward this point has been inexorable. Modern research has filled in ever more detail of how our appetite and metabolism is controlled and why we gain weight.
The consequences have been known for centuries.
Despite the increase in technology, the bottom line remains the same - obesity is due to consuming more calories than are burned and our modern lives are predispose to this.
In order to reverse this trend, we must fly in the face of evolution.
Due for review October 2013