Dieting fact and fiction

Cosmos Magazine


Cosmos is a quarterly science magazine. We aim to inspire curiosity in ‘The Science of Everything’ and make the world of science accessible to everyone.

By Cosmos

If the size and influence of the diet industry and the battles many people wage – often over decades – to control their weight seem nonsensical to you, Why Diets Make Us Fat will be perfect fodder to bolster your case next time the topic comes up.

Aamodt, a neuroscientist, explains the science behind the way your body controls your weight, showing why it can be so hard to lose those extra pounds. A host of sobering statistics reveal just how taken in we are by empty (and expensive) promises. In her native US, Aamodt says, 108 million people – about a third of the population – went on diets last year, and half of them were within a healthy weight range when they started. In Europe, as far back as 2002 (according to an industry report), 231 million people attempted some form of diet, with only 1% achieving permanent weight loss.

The story of our battle with our weight isn’t just about losing it, but keeping it off, and one of the linchpins of Why Diets Make Us Fat is the body’s weight-control mechanism, an ideal weight range your brain will fight tooth and nail to keep you within. It’s determined by genetics, and it works perfectly if you let it.

In a habitat like we evolved in (i.e. one without billboards exhorting us to consume what we don’t need or the social strictures of eating certain meals at certain times), we’d eat when we were hungry, stop when we were full and stay within our pre-determined weight range without too much effort.

The trouble, as Aamodt spends a lot of the book outlining, is that moving our weight outside that range is both extremely hard and unhealthy. Fall below it and your brain will assume you’re starving. The conscious manifestation is a feeling of sluggishness and constant cold, and the brain works harder to extract what nutrients it can, taking resources away from immunity or other systems. Even after years of dieting, it will try to raise your weight back to your accepted range, which explains why sustained weight loss is so difficult.

As Aamodt points out, the effort/reward chemistry of the brain plays a part too, with hormones encouraging us to eat more when we’re dieting, making it that much harder.

Scientific research the book cites puts a pin in many of the dearest-held beliefs about dieting. The results aren’t that different whether we’re on low-carb, low-fat or intermittent starvation diets, and the rate of weight loss doesn’t change the end result much either.


C71 review fat 2

Big Fat Myths
By Ruben Meerman
Penguin Random House Australia (2016)

In the constant battle between salespeople spruiking costly diet products and diet books, the first casualty often seems the truth. There cannot be many weight watchers who have not at least once scratched their heads in bemusement about how their bodies really do work and how they burn those unwanted kilograms.

Enter Ruben Meerman with this admirably concise guide to the science of losing weight. He brings the clear-sighted perspective of a physicist to the question (which he calls the Big Fat Question, or BFQ), “When someone loses weight, where does all the fat go?”

The short answer is that it is converted to carbon dioxide and water, but in arriving there Meerman leaves no myth unbusted.

It’s highly nutritious fare.


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