"Eat less, move more" must rank among the most misleading pieces of dieting advice ever offered. Not only does the adage minimise the difficulties of losing weight, it ignores the reality of the way our food is mass-produced, advertised and marketed.
Multinational food companies promote hyper-rewarding foods that are both energy-rich and nutritionally poor. Packed with sugar, salt and fat, they do us little or no good while tasting absolutely delicious and being almost impossible to resist. Why does unhealthy food taste so great?
Tastiness has far less to do with micronutrient content than the amount of energy the food delivers. The brain's energy requirements are astronomical. The adult brain, although accounting for just two per cent of body weight, demands 20 per cent of the energy consumed at rest (the resting metabolic rate or RMR). Among children, whose brains grow rapidly, energy demands vary between 43 per cent and 85 per cent of RMR. Which explains why anything that tastes sweet and is high in energy proves so appealing to youngsters.
Our primary nutrient sensor is located in the hypothalamus, deep within the brain. Regulating a host of physiological behaviours, this region is, like all of the brain, able to change in response to experience. Known as "plasticity", it's a blessing and a curse. On one hand, it enables us to learn and adapt to circumstances. On the other, when chronically exposed to hyper-rewarding food, it creates a craving for gratification over nutritional needs.
Energy-dense foods cause the release of the neurotransmitter dopamine – dubbed the "gas pedal of pleasure" – together with other brain-pleasers such as endogenous opiates, beta-endorphins and endocannabinoids.
This tsunami of hormones underpins the pleasurable feelings that are produced by consuming sugar, fat and salt. As we seek to repeat the rewards through further consumption, the brain sets out to restore balance (maintain homeostasis) by depleting or "pruning" dopamine receptors. In order to get the same food "fix", more has to be consumed. After a while this creates tolerance – more usually applied to the diminished sense of delight or momentary escape people get from drugs and alcohol. The fact that the term is now being employed in connection with food demonstrates the biological liability imposed by our present obesogenic food environment.
Once someone has learned to prefer high-energy-dense foods – which typically occurs early in life – hypothalamic and reward signalling become sluggish when faced with healthier foods which are not so rewarding. As a result, these tend to be avoided – most people would sooner eat an ice cream than an apple.
This fact is being exploited by Big Food. Produced cheaply and mass-marketed, high-energy-dense products are the fast track to huge profits and ever-expanding population waistlines.
Obesity is not the result of eating too much and moving too little, as those involved in producing, advertising and selling food would have us believe. The obesity pandemic results from a series of endocrine, metabolic, neurocognitive and physiological adaptations, fostered by abundance.
There is no such thing as the "wisdom of the body". Rather, the body responds to the inputs it receives with the result that we humans are busily digging our graves with our teeth.
This article was first published in the September 2015 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online
This article was originally published by WIRED UK
