I remember a letter sent to the Financial Times some time last year from a farmer who claimed it wasn't surprising that obesity rates have increased because nowadays, with the ubiquity of central heating, we expend less energy simply on keeping warm, but we haven't reduced our calorie intake to compensate.

The Letter (from march 2018) claims:

Your statement that “the rise in total energy intake through diet is the main cause of rising obesity levels” cannot be true because in the UK calorie intake has trended down both recently and indeed for over a 100 years. ... The scientific reality is that, being mammals and warm-blooded, nature intends that some 70 per cent of our calorie intake should be used to generate heat ... The reality — as every farmer knows — is that weight gain increases in warm accommodation. In short, modern obesity derives from the introduction of universal central heating, heated cars, and heated workplaces.

But I've been wondering about this letter for a while. Is there any evidence to support the hypothesis?

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    We might heat our homes more but we are also wearing less clothing inside. People used to no heat their bedrooms at all but they had much thicker bedding, wore a night cap and used a hot-water bottle to heat their bed. They also didn't sit in their living room only wearing a T-shirt during winter. People are more likely to be obese because they (i) eat more calories, (ii) have an office job, and/or (iii) spend their free time in front of a TV, computer or smart-phone. It should be easy to find studies proving this rather obvious relationship which would mask any effects of the proposed one. – Roland Dec 13 '18 at 11:48
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    Hello and welcome to Skeptics SE. Skeptics SE exists to examine notable, referenced claims. A claim is notable if it is made by a significant person, ditto news outlet or social forum and then shared by a large number of people. It is referenced when anyone reading this post can find the claim easily from the post (typically just clicking a link). In order for your post to reach this standard you will need to 1) link to the issue of Financial Times and 2) show that the person that sent the letter is significant. Edit these things into the post and you are likely get an answer. :-) – MichaelK Dec 13 '18 at 12:02
  • Welcome to Skeptics! At the moment, you haven't got a notable claim. If you search for "central heating obesity" there are plenty of examples of the claim with references. Find at least one you doubt, and link to it here and quote from it. – Oddthinking Dec 13 '18 at 13:28
  • At least one part of what the letter says is true: An ERC-funded study from 2013 has found that the average calorie intake in the UK has decreased over the last 30 years (a development contrary to the US), while they still found an increase in average body weight. The authors consider this to be a puzzle: "if calories are declining, why is weight increasing?" (p. 18). They do not mention central heating at all, but suspect that the answer may be found in changes in physical activity. – Schmuddi Dec 13 '18 at 14:29
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    I really would like to know where they take these ideas from. 70% of caloric intake for heating? That would be a pretty shoddy organism then. This is obviously referring to BMR, Basal Metabolic Rate, which can indeed make up 50-80% of your caloric requirement (the rest being digestion and physical movement). BMR isn't "just heating", though. It's such niceties as your heart beating, lungs breathing, brain and CNS functioning, and all the chemical shenanigans that keep you from keeling over, being dead. Central heating doesn't save your body from any of that, as heat is mostly byproduct... – DevSolar Dec 13 '18 at 14:57

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