health · weight loss

Does heat make you fat? No wait, it’s cold…

Upfront confession: I have a high tolerance for headlines of the form “X makes you fat!” Posting these stories to social media. I’m often misunderstood. I’m never doing it to suggest that people stop doing X, for any value of X. Instead, I do because I like seeing that medical researchers agree that whatever causes fat, it’s more complicated, much more complicated than “calories in/calories out” or the simple formula for ending obesity that overweight people always get, “eat less and move more.”

Oh, I also hate sharing these stories because inevitably they are accompanied by a photo of a headless fat person. Oh, the shame! I lost my head. See No more headless fatties, why not use images of active fat people complete with heads instead? for my beef on that front.

Now, there are lots of proposed values of X, the list of things that cause obesity. In additional to the usual suspects (eating too much and moving too little) the list has included such things as street lighting (too much light at night disrupts our sleep rhythms), chemicals in plastics,  hanging out with fat friends, and my favourite, comfortable kitchens where people want to spend time. I just had my kitchen redone and now I think maybe I should go back to our one person-at-a-time galley thing that was falling off the back of the house.

“What a beautiful kitchen!” I hear my neighbour saying but I wonder if she’s also secretly thinking, “Too bad it’s making you fat!” Actually my kitchen isn’t that nice. Maybe just nice enough to make me pleasantly plump.

For the complete ridiculous list, see xojane’s list of 21 Things Making You Fat Right Now!

Here’s one such theory that I hear a lot. It’s central heating that’s to blame. Warm houses are making us fat.

Don’t turn up the heat! Put on a jumper! (That was the story of my youth.)

This story fits in well with my British heritage. “Jumper” should have been your first clue. I’m from the land of virtuous people living in cold houses. My family loves to retell the story of a great aunt who at the insistence of her children had central heating installed but reassured all visitors, with a smile, “I haven’t had it on yet.” I think she likely died without ever turning it on.

And truth be told, I’ve inherited a bit of that. I like cold rooms and lap blankets, warm kitchens with ovens on, and cold bedrooms with warm blankets. I even have a heated mattress pad. (My new fave feature of modern life is the smart phone app that allows me to get into bed and then turn down the heat and shut off lights. Brilliant.) I prefer hot spots in otherwise cold rooms. This makes sense as I also love old houses and these things go together.

Winters in Australia and New Zealand tested my tolerance for cold houses. I guess when the weather isn’t life threatening, you don’t see the same need for regular, reliable indoor heating.

And to add to the moralizing notes in this story, cold houses don’t just promote virtue (I think it’s because you’re not tempted to take off your clothes until after you’re under the blankets and sweaters on top of sweaters aren’t exactly the sexiest look around) they’re also better for the environment.

No surprise then that warm houses make you fat.

See Mark’s Daily Apple, Is central heating related to obesity?

See Readers Digest! 8 things that are making you fat

“Trying to lose weight? Turn down the thermostat. A cozy home could be contributing to making you fat, suggests research in the journal Obesity Reviews. When our bodies are cold, we shiver, causing our muscles to contract to generate heat—and burn calories.”

Even the New York Times weighed in Central Heating May Be Making Us Fat. And Time Magazine too, Why Indoor Heating May Make You Fat.

The authors of the new study, published in the journal Obesity Reviews, note that average indoor temperatures have risen steadily in the U.K. and U.S. over the last several decades, as central heating has become increasingly available — and rates of obesity have risen too. The average temperature in British living rooms went from 64.9 degrees F to 70.3 degrees F, from 1978 to 2008. Living rooms in the U.S. have long been heated to at least 70 degrees F. Indeed, average temperatures have gone up all throughout the house — and in the wintertime, people tend not to leave their homes much anymore, at least not unless it’s in a heated car.

“Increased time spent indoors, widespread access to central heating and air conditioning, and increased expectations of thermal comfort all contribute to restricting the range of temperatures we experience in daily life and reduce the time our bodies spend under mild thermal stress — meaning we’re burning less energy,” said lead author Fiona Johnson in a statement. “This could have an impact on energy balance and ultimately have an impact on body weight and obesity.”

Although humans are born with significant deposits of brown fat — the primary purpose of which is to regulate body temperature by burning energy for heat — those stores diminish over time. By adulthood our brown-fat stores have shrunk, having been replaced with the more familiar white fat, the stuff that hangs over belt buckles and swings from the backs of arms.

And I’d love to love this story. Yes, get out of your comfort zone, go play outside, stop burning fossil fuels. Live like our ancestors used to, etc etc.

But now, it’s cold, not hot, but cold, that makes you fat. That journal article was published in 2011, but new research published the same journal years two later says it’s cold, not heat, that packs on pounds.

See Study: turn up heating to fight fat this holiday season.

An interesting new study from the UK reveals that people who live in well-heated homes are not as likely to be obese or have a high body mass index, compared with individuals who keep their houses cooler.

The researchers, from the University of Stirling in Scotland, have shown a link between higher temperatures and lower levels of body fat by studying over 100,000 adults who rely on central heating from 1995 to 2007, in the nationally representative Health Survey for England.

Although the researchers note that scientists have recently suggested warmer indoor temperatures could be contributing to rising obesity levels in the US, Canada, the UK and Europe, this latest study suggests the opposite is true.

Back and forth, to and fro. This debate ought to be familiar. I’ve heard it before  about swimming in cold water (see here and here). And I’ve been bugging Tracy to blog about it. Swimming in cold water makes you fat! Wait, no, bathing in ice cubes makes you slim. Thank Tim Ferris for that suggestion. Read about his “ice diet” here. Um, no thanks, Tim.

Keep your house at a temperature you like that’s consistent with caring for the environment. Swim in cold water if that’s what you like.

Because we really don’t know what’s responsible for the increase in obesity rates and we’re even less certain when it comes individuals what factors are that make a difference.

If there’s something to be learned here, it’s something I got from Precision Nutrition’s lean eating program, you are your own expert. Try different things and see if they make a difference for you.