{"id":1096,"date":"2019-02-11T02:49:54","date_gmt":"2019-02-11T02:49:54","guid":{"rendered":"http:\/\/commodityconversations.com\/wordpress2\/?p=1096"},"modified":"2019-02-09T13:30:08","modified_gmt":"2019-02-09T13:30:08","slug":"sleep-and-obesity","status":"publish","type":"post","link":"https:\/\/commodityconversations.com\/wordpress2\/2019\/02\/11\/sleep-and-obesity\/","title":{"rendered":"Sleep and obesity"},"content":{"rendered":"\n

When I was researching my book \u00ab\u00a0The Sugar Casino\u00a0\u00bb<\/a>, one of the questions that puzzled me was why we are consuming more calories than in the past. Referring to USDA data,<\/a> I wrote, <\/p>\n\n\n\n

\u00ab According\nto the loss-adjusted food availability data, Americans are consuming more\ncalories per day than they did 40 years ago. In 1970, Americans consumed an\nestimated 2,109 calories per person per day; in 2010 they consumed an estimated\n2,568 calories\u2026.<\/p>\n\n\n\n

The average\nAmerican is eating 459 calories more each day today than he, or his parents,\nwere eating in 1970. \u00bb<\/p>\n\n\n\n

I have now, rather surprisingly, found part of the answer to that question in \u00ab\u00a0Why We Sleep: The New Science of Sleep and Dreams\u00a0<\/a>\u00bb by Matthew Walker,<\/a> a British scientist and professor of neuroscience and psychology at the University of California, Berkeley. He was previously a professor of psychiatry at Harvard Medical School. (An article in last week\u2019s Guardian newspaper <\/a>summarised some of the main themes of the book.)<\/p>\n\n\n\n

Regarding\nthe effect that sleep has on health, particularly on obesity, Mr Walker\nexplains that two hormones in your brain control your appetite: leptin and\nghrelin. Leptin signals a sense of feeling full, while ghrelin triggers a\nstrong sense of hunger.  He writes that clinical tests have shown that\n\u00ab inadequate sleep decreased concentrations of the satiety-signalling\nhormone leptin and increased levels of hunger-instigating hormone\nghrelin. \u00bb <\/p>\n\n\n\n

Looking to\nsee what this might mean in practice, one clinical test found that individuals\nwho slept between four and six hours per night consumed 300 calories per day\nmore than individuals who slept eight and a half hours per night. He writes,\n\u00ab Scale that up to a working year, and assuming one month of vacation in\nwhich sleep becomes abundant, and you will have consumed more than 70,000 extra\ncalories. Based on calorific estimates, that would cause 10 to 15 pounds of\nweight gain a year. \u00bb<\/p>\n\n\n\n

But it is not just a question of how much you eat, but also what you eat. Sleep loss increases the levels of endocannabinoids which, like marijuana, can give you the \u00ab\u00a0munchies\u00a0\u00bb. <\/p>\n\n\n\n

In one test, participants were given access to an unlimited lunchtime buffet. \u00ab\u00a0Despite eating almost 2,000 calories during the buffet lunch, sleep-deprived individuals dove into the snack bar. They consumed an additional 330 calories of snack foods after the full meal, compared to when they were getting plenty of sleep each night.\u00a0\u00bb<\/p>\n\n\n\n

Tests also found that sleep deprived individuals were 30 to 40 percent more likely to have cravings for sweets, carbohydrate-rich foods, and salty snacks compared to protein-rich foods such as meat or fish. <\/p>\n\n\n\n

And Mr\nWalker counters the argument that your body needs more calories the less it\nsleeps. He writes, \u00ab Sleep, it turns out, is an intensely metabolic active\nstate for body and brain alike. \u00bb What\u2019s more, the less you sleep, he\nargues, the less active you will be during the day. He writes, \u00ab inadequate\nsleep is the perfect recipe for obesity: greater calorie intake, lower calorie\nconsumption. \u00bb He continues,<\/p>\n\n\n\n

\u00ab\u00a0Of course, the obesity epidemic that has engulfed large portions of the world is not caused by lack of sleep alone. The rise in consumption of processed foods, an increase in serving sizes, and the more sedentary nature of human beings are all triggers. However, these changes are insufficient to explain the dramatic escalation of obesity.\u00a0\u00bb<\/p>\n\n\n\n

To\nemphasise the point, Mr Walker plots the reduction in sleep time (dotted line)\nover the past 50 years in the US on the same graph as the rise in obesity rates\n(below). <\/p>\n\n\n\n