Free markets may keep the economy in better shape than regulation, but that does not necessarily apply to people, according to a recent study published by the World Health Organisation. Researchers say governments could slow and eventually reverse the growing obesity epidemic by regulating fast foods such as burgers, chips and fizzy drinks to help combat weight gain. The WHO is urging governments to consider incentives for growing healthy, fresh foods - and disincentives for industries selling ultra-processed foods and soft drinks.

The research, led by Roberto De Vogli of the University of California, Davis, included the effect of deregulation on fast-food consumption, and the correlation between fast-food sales and increased body-mass index in 25 high-income countries from 1999 to 2008. "Unless governments [act]," De Vogli said, "the invisible hand of the market will continue to promote obesity." Separately, an American study of more than 30,000 middle-aged adults involved in national health and diet surveys from 1988 to 2010 has added to evidence that limiting sugar intake could lead to healthier hearts and longer lives. Lead author Quanhe Yang of the US Centres for Disease Control and Prevention called the results sobering.

The heavy hand of regulation alone may not persuade people to follow healthier diets when convenience and affordability are factors. And while shedding excess weight may reduce the health risk, being overweight is not the same as being obese. A recent analysis of nearly 100 studies involving Americans, Chinese and Europeans, published in the journal of the American Medical Association, confirmed that people who were overweight rather than obese died at slightly lower rates than people of so-called normal weight, perhaps because they are assessed more proactively for blood pressure and cholesterol or are more conscious of the need to exercise. None of this necessarily points the finger at fast foods. It does point to the need for more education about the benefits of a properly balanced diet and the importance of affordability.