In the US and UK in particular, were getting significantly fatter. For thousands of years, human body weight had stayed remarkably stable. Millions of calories passed through our bodies, yet with rare exceptions our weight neither rose nor fell. A perfect biological system seemed to be at work. Then, in the 80s, something changed.
Three decades ago, fewer than one Briton in 10 was obese. One in four is today. It is projected that by 2050, Britain could be a "mainly obese society". Similar, and even more pronounced, changes were taking place in the US, where researchers found that not only were Americans entering their adult years at a significantly higher weight but, while on average everyone was getting heavier, the heaviest people were gaining disproportionately more weight than others. The spread between those at the upper end of the weight curve and those at the lower end was widening. Overweight people were becoming more overweight.
What had happened to add so many millions of pounds to so many millions of people? Certainly food had become more readily available, with larger portion sizes, more chain restaurants and a culture that promotes out-of-home eating. But having food available doesn't mean we have to eat it. What has been driving us to overeat?
It is certainly not a want born of fear of food shortages. Nor is it a want rooted in hunger or the love of exceptional food. We know, too, that overeating is not the sole province of those who are overweight. Even people who remain slim often feel embattled by their drive for food. It takes serious restraint to resist an almost overpowering urge to eat. Yet many, including doctors and healthcare professionals, still think that weight gainers merely lack willpower, or perhaps self-esteem. Few have recognised the distinctive pattern of overeating that has become widespread in the population. No one has seen loss of control as its most defining characteristic.
"Higher sugar, fat and salt make you want to eat more." I had read this in scientific literature, and heard it in conversations with neuroscientists and psychologists. But here was a leading food designer, a Henry Ford of mass-produced food, revealing how his industry operates. To protect his business, he did not want to be identified, but he was remarkably candid, explaining how the food industry creates dishes to hit what he called the "three points of the compass".
Sugar, fat and salt make a food compelling. They stimulate neurons, cells that trigger the brain's reward system and release dopamine, a chemical that motivates our behaviour and makes us want to eat more. Many of us have what's called a "bliss point", at which we get the greatest pleasure from sugar, fat or salt. Combined in the right way, they make a product indulgent, high in "hedonic value".