Overweight and obesity's cause might be dead simple - eat more kilojoules then you burn up and you'll store the extra kilojoules as fat. But David Kessler, a former commissioner with the US Food and Drug Administration, argues that there's something going on in food manufacturing that's conditioning us to overeat. He calls it hyperpalatability and, put simply, it's the creation of moreish flavours in food that so stimulate the appetite that they override the body's normal controls to stop eating.
Kessler, a Harvard trained doctor and lawyer - and former overeater - wanted to understand why he and so many other people had such trouble resisting foods high in fat, sugar and salt. His search for answers resulted in The End of Overeating, a book that looks at emerging research into food addiction and concludes that, for many of us, highly flavoured foods oversupplied with fat sugar and salt, are too easy to overeat. You can argue that this is partly because they're so often combined with textures that are so easy to chew, but Kessler also points to research suggesting these foods have addictive qualities because they can trigger opioids, 'feel good' chemicals in the brain. Eat these foods often enough, so the theory goes, and we can become conditioned to wanting them more and more - even when they're causing unwanted weight gain or other health problems. Adding more fuel to this argument are human studies that have found that naloxone, a drug used to treat heroin dependence by blocking the release of opiods in the brain, can reduce food cravings.
The evidence for food addiction is a long way from being iron-clad but it's being taken seriously - at the Rudd Centre for Food Policy and Obesity at Yale University in the US, for instance, researchers have developed the Yale Food Addiction Scale - a series of questions on eating habits that attempts to identify people who might have addictive behaviours around food.
But what's also fascinating in Kessler's book is its peek into how food technology amps up the flavour of food to appeal to our taste buds and get us eating - at least in the US. When Kessler gets a food technologist to analyse the ingredients in a restaurant chain's chicken wings, the result goes something like this. The chicken meat - removed from the bone to make it easier to eat - is pumped with water, salt, hydrolysed soy protein and sodium phosphate to bulk it up and make it softer. It's then battered and crumbed with ingredients, including corn syrup solids, dried yeast and soy bean oil so that it becomes crispy when it's fried. It's then combined with a sauce made with sugar, hoisin sauce, soy sauce, chili paste, modified food starch and concentrated orange juice. Just in case that's not enough flavour, there's a dressing made of mayo, buttermilk and wasabi - and the whole lot's served with crispy fried noodles.