Obesity Part 4
This is, I promise, my last blog on this subject for the time being. It takes the form of a number of points made in recent publications
- Body Mass Index (BMI) “vastly underestimates” true obesity. This has been shown by the use of DEXA scanning to measure total body fat volume and comparing the rate of obesity identified with that shown by measuring BMI. Nearly 1,000 US adults aged 20-59 were assessed. 36% were classified obese by BMI but 74%, twice as many, by scanning. The addition of waist circumference halved the rate of mis-classification.
- Those trying to lose weight overestimate their diet quality. Control of body weight is aided by a proper understanding of dietary quality. One way of measuring quality of diet is the Healthy Eating Index (HEI). This Index is a measure of diet quality used to assess how well a set of foods aligns with key recommendations and dietary patterns published in the Dietary Guidelines for Americans (Dietary Guidelines). The Dietary Guidelines is designed for nutrition and health professionals to help individuals and families consume a healthful and nutritionally adequate diet. A good understanding off the HEI should make it easier for people to understand what they should eat but this study makes it clear that a very small minority can accurately assess how healthily they are eating – and even when coached in this discipline they usually still get it wrong. My own view is that it is extremely difficult to get people to change the way they eat. So eat what you enjoy but try to eat less of it (portion control)!
- Body mass index and all cause mortality: This study was a meta-analysis of more than ten and a half million participants worldwide. Using the baseline figure for those with a BMI of between 20 and 25, the increased risk of death over the following five years was thus:
BMI 25.0-27.5 1.07
BMI 27.5-30.0 1.20
BMI 30.0-35.0 1.45
BMI 35.0-37.5 1.94
BMI 40.0+ 2.76
It doesn’t matter much if you are slightly overweight but after that increasing weight leads to an exponential increase risk of premature death.
- Accepting obesity shouldn’t stop us warning of its dangers: Should we define obesity as a disease or as a risk factor? Fat shaming does not help anyone but neither does the trend for normalisation of fatness. The price of obesity is huge – not only because of the costs of managing weight problems but also because of the costs of managing all its consequences- diabetes, knee replacements, cancer, and all the other nastys following in its wake. The December BMJ included the “fact” that obesity costs the NHS £6.1 billion a year – in my view a hopeless underestimate. An estimate of the full annual cost to the UK economy is around £58 billion Taking into account all the ancillary costs, a recent estimate of the cost in the US is $2 trillion!
- Increasing the risk of cancers: The World Cancer Research Fund International has identified twelve cancers which are more common in obese individuals: mouth & throat, gullet, stomach, pancreas, gallbladder, liver, colon & rectum, breast, ovary, uterus, prostate and kidney.
- Running vs walking for weight management: A study of 32,000 runners and 15,000 walkers has concluded that running is much more effective for weight control than walking. This is not surprising – running cranks up the heart rate more and burns significantly more calories per unit time than walking. However there are a number of barriers to running – it is more uncomfortable, it may be restricted by musculoskeletal problems such as arthritis of the knees or ankles and it is more likely to cause injuries. According to Harvard Health, walkers have a 1-5% chance of injury while runners have a 20 – 70% chance. However, most of these injuries, to joints or muscles, are minor and cause only short-term problems.
If you are thinking of taking up running, try the Couch to 5k App – and join a local “parkrun” at 9 am on Saturday mornings.
And the increased fitness afforded by being a runner also has enormous benefits in preventing an array of degenerative diseases of later life. A runner is most unlikely ever to become frail.
- Obesity and dementia: The modifiable risk factors for dementia include physical inactivity, current smoking, depression, low education, diabetes, mid-life obesity, hypertension and hearing loss. The US Behavioral Risk Factor Surveillance System assesses the importance of each of these and has recently concluded that mid-life obesity has now overtaken physical inactivity as the most important.
- Semaglutide (Wegovy) and its heirs: The development of effective weight-losing medications is only just beginning. In the pipeline are numerous different hormone-based anti-obesity drugs. Many of them are used for treating diabetes. The enormous potential profits which they will bring Big Pharma ensures that they will be reaching chemists’ shelves as quickly as they they can be tested and manufactured. How appropriate they will be is debatable, remembering affordability, potential bone loss, ill effects on mental health, and other side effects – never mind the probable reduction in physical activity which they may promote.
Well, that’s all for now. Next time we will have a guest blog and after that I will try to keep you up to date with new scientific evidence on the benefits, and occasional harms, of physical activity.
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