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Slimming Down the World: but How?

December 31, 2012

By Fiorenzo Conte

Between 1980 and 2008 Mexico saw the percentage of its overweight population increasing of 31%. In the US the increase of the overweight population was of 24%, in South Africa and Brazil of 26%. These countries are just the tip of the iceberg of a trend – increase in overweight – which is affecting a lot of countries around the world. As the world is getting more round, policymakers are concerned about the healthcare costs that such epidemic will impose. The Economist published a special report which has interesting insights on why the world is getting round and how one could make it less round. It has some blind spots too. Here are my takeaways.

Choice, Biology and Environment. Many have defined obesity as a disease of choice: it is not that people cannot get enough food as in the case of under nutrition, it is that they chose to eat unhealthy food, to  buy sodas and to sit on their couches rather than exercising. Being overweight however is not exclusively the outcomes of one’s choice as it is also the outcomes of one’s genes. The human body has in fact evolved over the millennia to gain weight rather than to lose it. A series of hormones excite obese people at the sight of junk food while reducing the satisfaction from eating it. When people gain weight the level of leptin, the fullness hormone, increases to a level where the brain does not respond to it: this conjures up to make people obese. This mechanism served the cavemen to store food, it does not now. Genes and hormones also explain what keep people obese: when they try to lose weight genes defend the body to lose weight. In sum, genes do not explain the recent increase in overweight people, yet they explain why between two people who have similar food habits one ends up with a belly and the other not.

What Choice? (source manbicep.com)

It has important consequences too: given that many people become overweight when they are children for reasons beyond their choice (finding sodas in their school lunch box) then their ability to lose weight is constrained by human genes. Human biology however is not destiny and this is proven by one fact: rich people managed to stay on average slim while poor people are more fat. The Economist does recognize that socio-economic factors (poor people tend to have less access to exercise and less ability to refrain from yummy unhealthy cheap food) play a role yet it fails to explore at more length the reasons why less well off people are more affected by obesity than better off. For example, one of the most in vogue thesis is that poor people are more obese because they live in a healthy-food desert. A recent study disproved this thesis because it found out that poor people have access to fresh food as much as to junk food, thus pointing to the fact that it is more about purchasing power than access. A more thorough discussion about how socio-economic factors contribute to obesity could have helped to better underpin the discussion about how one can slim the world down.

It’s About Eating Less Junk Food. If one is asking how one can contain the obesity epidemic the answer is a change in diet. The Economist makes it clear: physical activities alone will not work, people need to change their diet which translated means they need to eat less junk food. If one wants people to eat more healthy then the simpler way to do so is to make healthy food more appetible: food companies have therefore a big role to play. However they face a conundrum:

Companies have a duty to their shareholders to make money. All big food companies are working hard to sell more products to more of the world. Many unhealthy products are very profitable. But companies do not want to be vilified for helping to make people fatter.

For this reason food companies will not change overnight and replace French fries with fresh salads. They will continue to sell fizzy drinks and chips until consumers buy them. Food companies will not change their menus in a short time (timing is very important here) unless governments will force them to do so.  Here comes in the nanny state.

What Works? Policymakers around the world are making steps towards containing the obesity epidemic in an attempt to bring down healthcare costs. Some are imposing a penalty on obese people (by fining companies which fail to reduce the number of overweight employees), some are nudging their citizens in healthy habits (like exercising), some are informing their citizens about the calories intake of their meals, some are raising prices of junk food through taxes. Governments are faced with a conundrum too however: they do not know what intervention works to slim down its citizens. Given the evidence-based policy mantra, there is a quest for implementing policies which are backed up by evidence (preferably as rigorous as randomized control trial). One knows that no one single policy will do the job, but there is very little evidence about what bundle of policies will be effective at reducing the number of overweight people.

Looking for  conclusive evidence for any kind of policy is not however necessarily the way to go. To understand why, look at the drop of murder rates in the major US cities: murders went down, yet there was no “hard” evidence that any single intervention which were implemented to tackle murders (broken-windows strategy, community policing etc) contributed to this drop. It might be that one proves that taxing sugary drinks does not prevent people from buying sugary drinks, yet it might be that taxing plus information plus reduction in sale outlet selling sugary drinks could work. It is difficult to isolate the impact that one policy has on the outcome (drop in obesity) hence looking for definitive evidence (policy x reduces by 25% outcome y) might just be not an option when one faces an obesity ticking bomb. Policymakers will have to go with interventions which are backed by partial evidence and find other ways to push for politically unpopular moves.

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