MEDICAL MATTERS:GIVEN MY strong feelings about the stigmatisation of those who are overweight or obese, anyone focusing in on today's column expecting a public health missive on the absolute need for a perfect body mass index (BMI) will be sorely disappointed. Although this is a special supplement on obesity, I wish to take a somewhat contrarian view of the subject and acknowledge the reality of obesity as a complex, sometimes organic body type.
It’s worth noting some cultural differences that precede the current view of obesity as a “raging epidemic”. In Chinese culture, there is still a widespread belief that carrying some extra weight is a sign of health and prosperity; not surprising when you consider the country’s history of famine and malnutrition.
Obesity is seen as a sign of wellbeing in some parts of Africa; in countries ravaged by Aids it is perhaps inevitable that being fat is a good thing in the context of it being a strong signal that a person does not have HIV. And in the Pacific Islands cultural beliefs equate being overweight with beauty and sexual desirability.
Medication, too, plays a part in some people’s transition from Twiggy-like proportions.
A study published in the International Journal of Obesityfound that among more than 11,400 adults with high blood pressure and/or diabetes, those on beta blockers weighed more and had larger waistlines.
The Australian researchers found that people on beta blockers generally burned fewer calories and fat after a meal. They also reported lower physical activity. Overall, the patients were anywhere from 5kg to 17kg heavier than a control group. The findings suggest that beta blockers lead to weight gain by curbing people’s calorie expenditure, the authors concluded.
Antidepressants, antipsychotic medication and even some drugs used in the treatment of diabetes are all associated with involuntary weight gain.
But perhaps the biggest reason we need to take a gentle approach to those who are overweight or obese is the concept of “weight creep”. This occurs to even the most successful losers of weight; in a matter of months or years the weight creeps back despite the initial success. And it even happens to those who are very motivated to lose weight and do so with relative ease.
Research carried out at the University of Melbourne in 2009 looked more closely at some biological markers following weight loss. The admittedly small number of participants successfully lost an average of 30 pounds in 10 weeks using an extremely low-calorie diet. Despite intense support when they returned to a less extreme diet, they regained 11 pounds over the following year. Significantly, they reported feeling a lot more hungry and preoccupied with food than before they lost weight.
The researchers picked up some interesting changes in the dieters’ bodies. Biochemically they were behaving as if they were starving. A gastric hormone called ghrelin, also known as the “hunger hormone”, was about 20 per cent higher than at the start of the study. Other hormones associated with suppressing hunger, peptide YY and leptin were also unusually low.
In other words it was like weight loss had put their bodies into a different metabolic state that set them apart from people who hadn’t tried to lose weight in the first place. The body was essentially defending itself with a number of different weapons aimed at gaining weight.
It now appears that once a person loses about 10 per cent of body weight, they become metabolically different to a similar-size person who is naturally the same weight. And it may also be that the brain changes the way it responds to food after dieting.
Might the answer be to aim for more modest weight loss? Studies suggest that even a 5 per cent weight loss can lower a person’s risk for diabetes and heart disease. But one thing is certain: if the latest research is replicated in larger studies, then governments and public health gurus alike will have to move from the culture of blame they have created around obesity to a more humane approach.