This week’s British Medical Journal contains a report of a study published this week in the journal Critical Care in which diabetes was found to be associated with an increased risk of organ failure (such as heart or kidney failure) and death from this, but obesity (in the absence of diabetes) was not. This is not the first piece of research that suggests that obesity is not necessarily as damaging to health and it is traditionally made out to be. I’ve attached an article here which summarises the research which casts serious doubt on the standard measurement of body weight (the body mass index or BMI) to predict health and risk of death. Following this, I’ve added an article which is outlines the dietary strategy that is most likely to prevent diabetes ” namely a diet low in foods that give substantial and sustained release of sugar into the bloodstream.
Observer Column – 27th November 2005
The fact that our collective mass has grown considerably of late has inevitably triggered warnings from health professionals about how this may swell our risk of weight-related conditions such as heart disease. Ideal weight recommendations traditionally come in the form of the body mass index (BMI) – calculated by dividing an individual’s weight in kilograms by the square of their height in metres. However, the usefulness of the BMI in adjudging heart disease risk has recently been called into question on the publication of a study in the Lancet. This research has found that, once other associated factors such as smoking and exercise habits were taken into consideration, BMI has no significant bearing on heart attack risk.
This study is not the only research which has cast some doubt on the relevance of the BMI as a predictor of our propensity to disease and death. Earlier this year, the journal Circulation published a study which found that in individuals having surgery for heart disease (coronary artery bypass), mortality after surgery was actually lowest in individuals whose weight was categorised as overweight (BMI 25 ” less than 30) or ‘high-normal’. These results and those of the recent Lancet study clearly cast some doubt on the appropriateness of standard medical recommendations that a ‘healthy’ BMI of between about 19 and 25 is ideal in terms of heart health.
While research which asks questions of the conventional wisdom regarding the relationship between BMI and heart health is interesting, it is perhaps not as telling as research which seeks to establish the relationship between this measure of body weight and overall risk of death. Earlier this year saw the publication of such a study in the Journal of the American Medical Association. In this research, underweight and obesity (a BMI 30 or more) were both associated with an increased risk of death. However, somewhat surprisingly, this study found that compared to those in the ‘healthy’ BMI category, those categorised as ‘overweight’ (a BMI of 25 ” less than 30) were actually at reduced risk of death.
One of the limitations of the BMI is that, while it tells us something about the weight of an individual, it does not inform us regarding how much of this weight comes from fat. Also, there is growing recognition that it is not fat per se, but fat which aggregates around the middle of the body (so-called ‘abdominal fat’) that is most strongly linked with health issues such as heart disease. The Lancet study, for instance, found that a higher ratio of waist circumference to hip circumference (waist-to-hip ratio) was very clearly associated with increased heart attack risk. Ideally, men and women should have waist-to-hip ratios no larger than about 0.90 and 0.83 respectively. From a health perspective, the evidence suggests that it is an individual’s waist-to-hip ratio, rather than their BMI, that represents their vital statistic.
Observer Column – 27th January 2002
Diabetes is not the most sexy of conditions, but it’s an important one. Characterised by raised levels of sugar in the blood stream, it can ultimately lead to diverse problems including blindness, gangrene, kidney disease, nerve damage and impotence, and is the third leading cause of death after cardiovascular disease and cancer. What is more, diabetes is turning into a bit of an epidemic in the UK, with the number of sufferers set to double over the next decade. But it’s not all doom and gloom. The good news is there is plenty of evidence that making informed dietary choices offers real potential in the treatment of diabetes.
The chief substance in the body responsible for keeping blood sugar levels in check is the hormone insulin. In diabetes, insulin simply doesn’t do its job. About one in 10 diabetics have what is known as type 1 diabetes, where the body fails to make sufficient quantities of insulin. In the more common form of diabetes, termed type 2 diabetes, there is usually plenty of insulin around; the problem is that the body has become resistant to its effects.
Whatever the precise nature of the diabetes, eating a diet that helps to keep blood sugar levels on an even keel is of obvious importance. Until recently, the traditional view has been that sugar, because it tends to cause surges in blood sugar levels, should be limited in the diet. On the other hand, starches such as bread, potato, rice and pasta are generally recommended by doctors and dieticians because of the long-held belief that they give slow, sustained releases of sugar into the blood stream.
However a growing number of nutritionists and nutritionally-oriented doctors are beginning to question the conventional wisdom behind the standard diabetic diet. Over the last two decades scientists have been busily testing carbohydrate foods (those containing sugar and/or starch) for the speed and extent that they release sugar into the blood stream. The sugar-releasing potential of a food is represented by a number known as it glycaemic index (GI). As expected, foodstuffs packed full of refined sugar such as soft drinks, biscuits and confectionery have been found to have high GIs. What comes as more of a surprise, however, is that many of the supposedly slow-releasing starches that pervade our diet turn out, in reality, to be fast sugar releasing. Potatoes and most refined starches such as breakfast cereals, breads, crackers, corn chips, white rice and pasta are now known to have high GIs. In contrast, foods that are truly slow sugar-releasing include oats, beans, pulses, vegetables other than the potato, wholewheat pasta, pumpernickel bread, apples, pears and citrus fruits.
Because low GI foods give less pronounced releases of sugar into the blood stream, common sense dictates that these foods should form the basis of the diabetic diet. Despite this logic, many doctors and dieticians have generally been resistant to embracing the GI concept. In fact, a recent article in the British Medical Journal announced that the influential American Diabetes Association (ADA) has dismissed the concept of the low GI diet. More than that, it has also recommended a relaxation of restrictions on sugary foods for diabetics. The ADA’s stance is based on its belief that there is little evidence for benefit from the low GI approach. But is this really the case?
There have been more than a dozen studies that have compared the effects of low and high-glycaemic diets in diabetics. Most treatment periods were between two and six weeks. One wonders how realistic it is to expect significant changes so quickly in individuals who may have had impaired blood sugar control for many years or even decades. Also, many of the studies involved relatively minor dietary changes, and study participants were often still permitted to eat plenty of destabilising foods.
Yet, despite these and other shortcomings, all but one of these studies showed improvements in some measure of blood sugar control and/or the levels of the unhealthy blood fats cholesterol or triglyceride in the blood stream (these tend to be raised in diabetes). Study after study concluded that eating a low glycaemic diet appears to serve diabetics well, and that the approach has merit.
While is may fly in the face of orthodoxy, there is a good case for the role of the low GI diet in combating diabetes. The ADA’s recent dismissal of the low GI approach to diabetes and it laissez-faire attitude to sugar is not only counter-intuitive, but appears to me to go against the grain of the current scientific evidence. My belief is this latest offering from the diabetes establishment is likely only to worsen the plight of diabetics and those at risk of this condition. Smack bang next to the British Medical Journal’s report trumpeting the ADA’s recommendations was another article entitled ‘Diabetic care must improve’. I couldn’t have put it better myself.