Fats don’t make you fat

Carbs trigger insulin by turning to glucose in the body – and insulin makes us fat

Having spent nine years working on a book about fats in our diet, author Nina Teicholz condemned the low-fat high-carb dogma that has dominated the debate on health and diet for the past 50 years in a single sentence: “Eating fat does not make you fat.” The low-fat hypothesis, she told the audience at the Weston A Price conference at Thomond Park, was nothing less than “a mass, uncontrolled experiment on the public”.

Blimey! Here we are, thinking we’re doing the good thing, cutting the fat off the breakfast bacon – if we’re even having breakfast bacon – and it turns out we’ve been nothing but a bunch of guinea pigs subject to the whims of bad science.

Teicholz's book, The Big Fat Surprise, is an in-depth analysis of how dietary science can be swayed by bias and power. Writing it, she says, "I felt like I was writing about the Mob".

Comparing dietary scientists to Mafiosi may seem a stretch, but The Big Fat Surprise is full of skullduggery, threats, suppression of evidence, men with monster egos and bad outcomes.


There is even a Don Corleone, and his name was Ancel Keys, a powerful, egotistical American scientist who formulated the hypothesis that a diet low in saturated fats would prevent heart disease, by lowering cholesterol. For his work, he wound up on the cover of Time magazine and became the most influential nutrition expert of the 20th century.

The problem with Ancel Key’s low-fat hypothesis, however, is not simply that it was wrong and gained ascendency only by suppressing all the evidence that disproved it. The big problem is that the consequences have been incalculable: we are all swimming with the fishes when it comes to our diets.

Teichholz points out that, back in 1983, Ireland had no problem with obesity. By 2010, however, we had moved right up the ranks of the overweight nations of the earth. The irony is that had we left things as they were, and kept eating our traditional diet of spuds and fatty bacon and creamy milk on porridge, then we would have been grand.

A study of men in Co Cork, for instance, carried out between 1957 and 1962, showed that the men lived to an average of 77 years, equal to the longest-lived people on the planet. No heart attacks, strokes or obesity there.

The paradox, of course, is that our diets need fat and without cholesterol, our bodies won’t work. In fact, fats are our friends, because fats and proteins give satiety to a meal, which means we know when to stop eating because we feel satisfied and full.

Why do we persist, then, in seeing fat as the enemy? Simple: we think fats in food equals fats in us. “Has there ever been a more unfortunate homonym?” asks Teicholz. “One word means two very different things: the fat we eat and the fat on our bodies. It’s so hard for our brains to fully grasp that there are two entirely separate definitions of fat.”

Carbohydrates, on the other hand, trigger insulin by converting to glucose in the body and it is insulin that makes us fat.

In his new book, Always Hungry?, the Harvard nutritionist David Ludwig spells this out in stark and revealing terms: "It's the low-fat, very high-carbohydrate diet that we've been eating for the last 40 years, which raises levels of the hormone insulin and programmes fat cells to go into calorie storage overdrive. I like to think of insulin as the ultimate fat cell fertiliser."

So how can you stop fertilising those fat cells? Ludwig says simply: “Cut back on processed carbohydrates and get the right balance of protein and fat in your diet. A high-fat diet is really the fastest way to shift metabolism.”

At this point, you might need to pinch yourself to make sure that you aren’t dreaming. Did you just read that a leading doctor says a high-fat diet is the way to go to be healthy and to have the ideal weight? You did. The world, as far as nutrition is concerned and as far as fats are concerned, has been turned upside down.

“We’ve followed the guidelines, we cut fat, we ate more grains and now we look so sick,” is Teicholz’s conclusion about how avoiding fats has cost so many people their good health for so long.

The good news, of course, is that in Ireland we have a climate that gifts us with the world’s best milk, cream, butter, cheese and red meats. Let’s return to putting our agricultural riches back on the table.

The Big Fat Surprise by Nina Teicholz is published by Scribe.

John McKenna is editor at guides.ie