Millions of years ago, plants were making fruits to disperse seeds. Once the seeds were ready to travel in animal stomachs, fruits concentrated more sugar and ripened. They became an important and safe source of energy. Consequently, our ancestors perceived fruit to be “sweet” and pleasurable.

Meanwhile bees were busy making a much sweeter food, which also had the highest naturally occurring concentration of sugar. It wasn’t long before hominids, other primates, and Winnie the Pooh risked bee stings and anaphylaxis for honey. Chimpanzees have developed clubs, whisks, levers, drills, and dippers just to extract honey. Humans have revered honey just as much: it was a divine offering in ancient Egypt, the Old Testament asserted that the promised land flows with milk and honey, and Hindus feed honey to newborns in a religious ritual.

Nowadays, honey like sweetness is found in everyone’s cupboards and everyone’s local shop. Earlier this month, the BMJ highlighted the danger of sugar and the powerful economic interests invested in manufacturing sugary products. For instance, the World Health Organisation (WHO) recommended in 2003 that sugar should not comprise more than 10% of daily energy intake. In response, the Sugar Association in the USA, and other trade bodies, reportedly threatened to cut off American funding of WHO.

At that time, Derek Yach was the WHO executive director overseeing the report. Last week he used the example above to illustrate how dominant business practices may present a barrier to halting the epidemic of non communicable diseases, from diabetes to cancers. At a recent breakfast seminar, he spoke of other barriers drawing on his experience in academia, in international health policy, in a multinational corporation, and now in a public health think tank.

Such barriers exist at different levels of society. Families often find that the healthiest choices are the toughest to practise. Researchers are adept at discovering and identifying causes and associations, but do not think sufficiently about implementation. Physicians focus on treatment and cure at the expense of prevention. Public health practitioners have also been accustomed to an “eradication” mentality, rather than adapting to the long term strategies needed to prevent non communicable diseases. Previous disease vectors, such as mosquitos, never had lobby groups and industries built around them, unlike the vectors of sugar, salt, alcohol, tobacco and so forth. At a national level, funding for health prevention is more susceptible to cuts than funding for treatments. Governments and corporations value public opinion and shareholders respectively, rather than long term goals.

Yach pointed out that in 2010, the US Chief Actuary stated “There is no consensus in the available literature or among experts that prevention and wellness efforts result in lower costs.” This kind of thinking has led to life expectancy actually decreasing for some populations in the USA—we heard that white women without a high school degree have lost five years in life expectancy between 1990 and 2008.

However, the first, and possibly most important, barrier that Yach identified was to do with us as individuals: we favour today’s pleasures over tomorrow’s rewards. Walter Mischel, an American psychologist, conducted famous experiments into immediate and delayed gratification in the 1960s, using hundreds of preschool children as the subjects. In the study, every child was offered a reward that was placed in front of them. If they could wait fifteen minutes though, they would receive double the reward.

In follow-up studies, children who could wait went on to have higher exam scores, a lower body mass index, and less drug use. Only 30% of children could wait. What reward was so powerful that children were unable to resist it? It was a marshmallow—tasty, soft, and nearly two thirds sugar.

Krishna Chinthapalli is the BMJ clinical fellow.