What GPs can do in the war against obesity epidemic
It is time for individual GPs to exercise medical responsibility over the world's most costly and rapidly increasing disease, says Professor Michael Lean
Obesity was declared an epidemic disease (prevalence of more than 15 per cent) by the WHO in 1998.
About 21 per cent of the population are now obese (BMI above 30kg/m2) and this figure is increasing steadily at about 0.8 per cent a year. Obesity has been recognised as a disease within the WHO international classification of diseases for more than 50 years.
We in the UK are not the most obese nation but we are well up with the leaders. More than 25 per cent of all adult Americans are now obese and we will reach that point before 2010 unless something is done.
If people took enough exercise then appetites would reset to ensure energy balance and they would not gain weight (old-fashioned postmen do not get fat). However, by the time obesity has developed it is very difficult to turn back the clock. Indeed, prolonged physical activity can be hazardous for the obese in terms of damage to joints.
Health economics of obesity
The greatest burden of ill-health and the largest economic costs come from people in the overweight (BMI 25-30kg/m2) rather than obese category. Health problems may not increase so much but the numbers of individuals affected are much greater.
Most people in Britain spend more than half their adult lives in this category. The savings that could be made by preventing progression from overweight into the obese category would probably amount to 1-2 per cent of total health care costs roughly equivalent to diseases like epilepsy or major cancers.
Most of the health hazards that result from obesity are multi-factorial and would not go away completely if obesity were abolished, but many, such as type 2 diabetes, would almost disappear.
The hazards are also all age-related and as the population ages the burden of ill-health attached to overweight and obesity will contribute an even greater burden on future health care costs.
Losing 5-10 per cent weight has been shown to prevent most cases of new diabetes over a four-year period, as
well as reducing lipids and blood pressure. These effects will translate as major cost-savings.
Prevention or treatment?
With any epidemic, the scale of the problem means individual doctors treating individual patients cannot solve the epidemic. So there is a requirement for effective public health-directed measures to prevent obesity. However, as with any serious epidemic disease, there is an immediate need for treatment for those affected. A number of evidence-based guidelines have evaluated the outcomes that should be sought and offered to patients and the means by which they can be achieved.
There are three main goals of treatment in managing obesity:
· To prevent or restrict weight gain
· To introduce a short period of weight loss, usually three to four months, with a target of losing 5-10 per cent body weight, which brings major medical benefits
· To prioritise the management of existing cardiovascular risk factors in obese subjects, because the cardiovascular risks of diabetes, hypertension, hyperlipidaemia and smoking are much greater in overweight and obese subjects.
What can dietitians do?
For some people, self-directed measures are sufficient to prevent weight gain and for an important minority to achieve and maintain medically important weight loss.
For patients with established obesity this opportunity has been lost and already secondary complications are developing. The input of professional dietitians can generate a weight loss of
5-10 per cent in around half of all patients, which is usually maintained provided there is continued professional contact.
Historically, the medical profession has often derided this result as failure.
But we now understand that it brings major medical benefits, preventing
60 per cent of new diabetes.
Only two drugs are currently licensed for use and possess adequate safety and efficacy testing. They work in different ways: orlistat by blocking fat absorption in the gut; and sibutramine by stimulating a sense of satiety so patients need to eat less often.
Both drugs produce a weight loss of 3-4kg more than diet and exercise alone. More importantly they help maintain a weight loss for at least two to four years with no sign that the drugs are losing their efficacy over time. Substantial diabetes prevention (37 per cent) has been shown for orlistat.
Most cardiovascular risk factors associated with obesity improve when there is weight loss with either of these drugs. However, the reduction in hypertension is attenuated by the noradrenergic mode of action of sibutramine. Orlistat has an independent effect on lipids and probably thereby improving diabetes control.
Both orlistat and sibutramine have time-limited licences, two years and one year respectively. The limit is now two years for sibutramine in the US. What this means in practice is that patients who are successful on these drugs have to be treated as off-licence if they continue beyond these time-spans.
Because orlistat is not absorbed into the body it really has very little capacity for long-term toxicity and the theoretical possibility of fat-soluble vitamin deficiency does not seem to be borne out in practice. With sibutramine it is important to continue to monitor blood pressure. This is a regulatory issue that must be resolved. Some doctors have attempted to circumvent the problem by switching patients from orlistat to sibutramine and back again.
It is not clear from the published literature whether patients who respond to one drug will respond equally well to another, but stopping an effective drug will result in relapse and weight gain.
What patients can do for themselves
To prevent weight gain for most adults it is only necessary to under eat by about 100-200 calories a day or alternatively to take the equivalent amount of exercise, which amounts to walking 20-30 minutes on five days a week. There are a number of ways to help patients reach the practical and achievable goals dietitians try to set.
The use of step counters fell away when questions were asked about their precision and accuracy. But the experience from the US programme 'America on the move' is helping us to realise that patients benefit enormously from feedback if they can set a modest and achievable target of 2,000-5,000 extra steps to walk in a day. A cheap step-counter can provide exactly that encouragement.
What should we be doing for obese children?
Obese children are a problem to every GP. Overweight toddlers are at little greater risk of adult obesity, but overweight teenagers are likely to develop into obese adults.
The physical health of children is seldom upset by obesity but their mental health may be, and in particular a vicious cycle of low self-esteem and overeating often secret overeating may set a pattern for life.
A handful of very obscure cases of extreme obesity have been shown to result from deficiency of the hormone leptin or its receptors and some can be treated with hormone replacement therapy. However, the number of cases worldwide is still in single figures.
For most families with an obese child all members of the family must recognise that they have a part to play in health improvement. It is important to recognise that palates can change quite rapidly. A short period of regular consumption of fruit and vegetables can change the preferences of people who claimed not to like the foods.
It is usually not appropriate to expect children to lose weight but rather to maintain their higher weight while they grow. But some teenage girls probably need to be managed more like adult women.
The option of surgery
There will always be some patients who fail to lose weight adequately or who are unable to maintain a lower weight. For these patients surgery has to be considered in view of the enormous health hazards patients face and the vast costs that a small number of extreme obese cases can present to health services.
It is better to intervene earlier rather than later to interrupt the time course of complications of obesity and this applies particularly to patients at high risk of metabolic syndrome (for example, those with a family history of diabetes or hypertension, or those with a high waist circumference greater than 35 inches in women and greater than 40 inches in men).
It is now time for health services and individual doctors to exercise medical responsibility over the world's most prevalent, most costly and most rapidly increasing disease.
As a first step it would help to start recording its presence, measuring height, weight and waist circumference of patients and recording a diagnosis with ICD code E.66 in medical records and hospital returns.
It is a difficult disease to understand, or to cure completely, but medical management is worthwhile and cost-effective.
Achievable lifelong measures
Simple behavioural measures can be adopted lifelong. These include taking no snacks of any kind between three main meals, taking no butter, margarine or other spread on bread, restricting alcohol intake to two units a day. Switching to low-fat foods without consciously restricting food intake is often enough to prevent weight gain. Obese subjects who successfully lose and maintain a weight loss of 25kg or
so follow low-fat diets and take roughly 5,000 steps a day more than unsuccessful patients.
The paradox of fad diets
As more people recognise the risks of obesity, fat provision in the diet should be reduced. The recent publicity for low-carbohydrate (Atkins-type) diets demonstrates that the public and many professionals are confused. Low-carbohydrate diets achieve apparent weight loss by depleting the body of water. They also deplete muscle glycogen, which makes it difficult to take exercise and in the long-term contributes to higher levels of cholesterol. During the period of weight loss all cardiovascular risk factors will improve whatever the composition of the diet, but that period of weight loss is time-limited.
Scottish Intercollegiate Guidelines Network
National Institute for Clinical Excellence
International Obesity Taskforce