[Guardian] When I saw the photograph I could scarcely believe it was the same country. A picture of Brighton beach in 1976, featured in the Guardian a few weeks ago, appeared to show an alien race. Almost everyone was slim. I mentioned it on social media, then went on holiday. When I returned, I found that people were still debating it. The heated discussion prompted me to read more. How have we grown so fat, so fast? To my astonishment, almost every explanation proposed in the thread turned out to be untrue.Unfortunately, there is no consistent obesity data in the United Kingdom before 1988, at which point the incidence was already rising sharply. But in the United States, the figures go back further. They show that, by chance, the inflection point was more or less 1976. Suddenly, at around the time that the photograph was taken, people started becoming fatter ‐ and the trend has continued ever since.
The obvious explanation, many on social media insisted, is that we’re eating more. Several pointed out, not without justice, that food was generally disgusting in the 1970s. It was also more expensive. There were fewer fast food outlets and the shops shut earlier, ensuring that if you missed your tea, you went hungry.
So here’s the first big surprise: we ate more in 1976. According to government figures, we currently consume an average of 2,130 kilocalories a day, a figure that appears to include sweets and alcohol. But in 1976, we consumed 2,280 kcal excluding alcohol and sweets, or 2,590 kcal when they’re included. I have found no reason to disbelieve the figures.
Others insisted that the cause is a decline in manual labour. Again, this seems to make sense, but again the data doesn’t support it. A paper last year in the International Journal of Surgery states that "adults working in unskilled manual professions are over four times more likely to be classified as morbidly obese compared with those in professional employment".
So how about voluntary exercise? Plenty of people argued that, as we drive rather than walk or cycle, are stuck to our screens and order our groceries online, we exercise far less than we did. It seems to make sense ‐ so here comes the next surprise. According to a long-term study at Plymouth University, children’s physical activity is the same as it was 50 years ago. A paper in the International Journal of Epidemiology finds that, corrected for body size, there is no difference between the amount of calories burned by people in rich countries and those in poor ones, where subsistence agriculture remains the norm. It proposes that there is no relationship between physical activity and weight gain. Many other studies suggest that exercise, while crucial to other aspects of good health, is far less important than diet in regulating our weight. Some suggest it plays no role at all as the more we exercise, the hungrier we become.