According to the Yorkshire Post (6 July 2013) Emma Lee has just received a letter which informs her that her daughter Katie, aged 11 years, is “overweight” as determined by criteria devised by the National Child Measurement Programme(NCMP). Mrs Lee is very concerned at the impact this letter may have because it makes young girls feel sensitive about their weight and consequently prone the development of eating disorders.
She goes on to explain that it is particularly inappropriate for Katie who is extremely fit. She takes the dogs for a walk every day. At school she does gymnastics and regularly plays rounders, touch rugby and hockey. As a member of the Scouts she often goes for long hikes at the weekend.
Mrs Lee is absolutely correct to be critical. The NCMP use Body Mass Index (BMI) to determine that a child is overweight. Those who are overweight or obese are considered to be at an increased risk of developing various diseases including heart disease later in life. As a consequence they and their parents are advised that it would in the best interests of the children that steps should be taken to alter the BMI so that it falls in the “normal/ideal” range.
Unfortunately this rationale is fundamentally flawed.
- BMI is not a reliable indicator of an individual’s state of health. For adults there is very little difference in life expectancy over the BMI range from 20 to 35, which includes the “normal”, “overweight” and “mildly obese” categories. In fact the greatest life expectancy is actually for those who are overweight (See BLOG 10).
- It is absolutely crucial to assess a person’s physical fitness. It has been established that those who have a reasonable amount of physical activity (eg walking about one mile per day) have a much greater life expectancy than those who are sedentary Irrespective of BMI. (See BLOG 12).
- There is plenty of evidence to show that losing weight is detrimental to health (See BLOG 31). So even if those who are deemed to be overweight attempt to lose weight by the conventional approach of reducing calorie intake there is certainly no guarantee that this will improve their health.
I must emphasise that my comments should be regarded as criticism of current public policy. This is not to deny that do have serious health problems, which are related to what people are eating and to the fact that many have a sedentary lifestyle.
The fundamental problem with food consumption is that there is excessive consumption of carbohydrates, primarily those which are refined such as sugar (See Blog 35) which is particularly damaging. This trend has been encouraged by the official guidelines which have successfully persuaded much of the public to that fat, especially saturated fat (SFA) should be reduced. This has resulted in the development of “low fat” products which are actively promoted as Healthy. Regrettably most are formulated by reducing the fat and replacing it with sugar!
The major health problem is the rapid growth in the incidence of diabetes which in Great Britain has doubled in the last 15 years. Those with diabetes have an increased risk of developing heart disease and many cancers. A person with diabetes is up to 4 times more likely to suffer from Alzheimer’s Disease than one who is free of diabetes. Diabetes is caused by a high level of glucose in the blood. This originates from the amount of sugar and other carbohydrates (such as bread, potatoes, pasta and rice) in the regular diet). Many who have been diagnosed with diabetes have overcome the disease successfully by reducing their consumption of carbohydrates (See Blog 33). There is also very good evidence that the SFA is an important source of key nutrients and by following the official advice to reduce the intake, with consequences that are detrimental to their health (See Blog 16).
There is no question that those who take some physical activity such as walking, gardening or regular sports have much better health and greater life expectancy than those who have a sedentary life-style. While it is often claimed that increasing physical activity will help to lose weight this only holds true if the degree of activity is extremely high and therefore completely unrealistic for the vast majority. By contrast, even limited activity is undoubtedly beneficial.
So the big problem we have is that the public health policies we have in this area are “not fit for purpose”. In fact it is only making things worse! The comments by Mrs Lee that the emphasis on losing weight contribute to various eating disorders are absolutely on the button.
So to sum up:
- Body weight per se in not the problem. The use of BMI to assess an individual’s health status is not effective and should not be used to underpin the policy.
- The dietary advice to reduce fat and SFA cannot be substantiated. It is highly relevant that between 1969 and 2000 the National Food Survey (NFS) shows that total fat consumption had fallen from 120 to 74 g/day. Over the same period the consumption of SFA decreased from 56.7 to 29.2 g/day. Despite this the “obesity crisis” has emerged. The official guidelines must be changed in order to recognise that there are many important nutrients present in SFA, that sugar intake must be subject to large scale reduction and that there are risks associated with excessive consumption of complex carbohydrates.
- Physical activity must be encouraged in people of all ages.