The co-author of The Pioppi Diet on the big fat lies fed to us by the food industry, plus why we should be consuming four tablespoons of olive oil a day.

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Tides are beginning to turn, but for decades, the conventional wisdom has been that saturated fat from foods such as meat, butter, eggs and cheese clogs the arteries leading to heart attacks. This misconception arose from American scientist Ancel Keys landmark Seven Countries Study where he demonstrated a correlation between the consumption of saturated fat in the diet with blood cholesterol levels and heart disease. It was Keys’ work from this study that led to a change in dietary advice in the USA and UK in 1977 and 1983 to reduce total fat consumption to less than 30% of calories, and more specifically saturated fat to less than 10% of calories. Advice that I and many others now argue has actually driven the twin epidemics of type 2 diabetes and obesity through increasing consumption of sugar, other refined carbohydrates and processed vegetable oils. A very well researched report by investment bank Credit Suisse published in 2015 revealed that 90% of the increase in calories in the American diet between 1961 and 2011 has come from refined carbohydrates and vegetable oils.

Eating fat is about as likely to make you fat as eating green vegetables is to turn you green.

Both from what we now understand of the biology around the development of heart disease, combined with robust modern scientific data, eating fat doesn’t actually make you fat  and saturated fat from the diet does not clog the arteries: it’s just plain wrong to claim that it does. In that vein, I’d like to dispel some big fat myths...

Fat - the facts

1. Fat in unprocessed food is, believe it or not, a crucial provider of essential fatty acids (linoleic acid and alpha linoleic acid) that are vital for immune function and maintaining the integrity of cells. Dietary fat is also essential for the body to obtain and absorb the fat soluble vitamins, A, D , E and K.

2. All unprocessed natural foods that are high in fat contain saturated fat: meat, fish, eggs and dairy, just to differing degrees, together with monosaturated and polyunsaturated fat. Dairy foods are the only food group that contain more saturated than unsaturated fat. Even extra virgin olive oil has 14%- 20% saturated fat.

3. Dietary fat is satiating. In other words, it helps you feel full for longer in comparison to refined carbohydrates and sugar, and therefore can help with controlling weight.

4. In comparison to protein and carbohydrates, dietary fat has the least impact on raising blood glucose and thus spiking insulin. And it is insulin resistance that is the most important risk factor for heart attack.

5. Some foods high in fat, in particular extra virgin olive oil and nuts, have been proven to actually prevent heart attack, stroke and death. We knew those Mediterraneans were onto something.

Fast food not fat food is the baddie

When Keys conducted the Seven Countries Study, many of the foods that were singled out as being high in saturated fat and harmful through correlation with heart disease were actually processed carbohydrate foods such as cakes, ice cream, biscuits, and pastries. In fact, this misconception still occurs with the media. How many times have you read articles or news stories on the subject of obesity in which eating fat or saturated fat is singled out as the culprit of disease, accompanied by an image of an overweight person digging into a plate of burger and fries?

The burger bun and chips are almost entirely made up of refined carbohydrate, made worse healthwise by the fact the chips have been cooked in vegetable oil.

Rather than calling it fatty food, the major issue with the burger and chips (aka, junk food) is the refined carbohydrate and vegetable oil content. “Fattening food” would be a much better description!

Keeping us sweet

As a result of misguided public health messaging that has wrongly demonised fat, and more specifically saturated fat, the food industry produced a market of “low fat” foods that were loaded with sugar. Fat makes food more palatable, so when you take the fat out of food that’s supposed to contain it, you end up with meals that taste of cardboard. To combat cardboard-gate, manufacturers chose an additive that was cheap to mass produce and tasted good: sugar. Through its links to type 2 diabetes, heart disease, high blood pressure and obesity, the evidence is now overwhelming that sugar deserves its current reputation as public enemy number one in the western diet.

Swedish doctor Andreas Eenfeldt, the brains behind the independent (of food and pharmaceutical industry interests) website sums it up perfectly when he says that, providing you cut the sugar and refined carbs, “eating fat is about as likely to make you fat as eating green vegetables is to turn you green”

A few months ago myself and two of the most eminent cardiologists in the world, Professor Rita Redberg from the University of California, San Francisco and editor of JAMA Internal Medicine and Pascal Meier, editor of BMJ Open Heart wrote a widely publicised editorial , citing up to date evidence and explaining the biology as to why insulin resistance and inflammation , and NOT dietary saturated fat, clogs the arteries.

We also mentioned a very important study that revealed that postmenopausal women who underwent repeat imaging of their coronary arteries three years after being diagnosed with heart disease had the least amount of progression of blood vessel narrowing in the ones that consumed the most saturated fat in their diet.

When veg isn’t best

Industrial seed oils, commonly known as vegetable oils, such as sunflower and corn oil have been marketed as healthy because they “lower cholesterol”. When we examine all of the studies of cholesterol lowering through diet, however, involving hundreds of thousands of people both healthy and with diagnosed heart conditions, not only do vegetable oils not prevent you from having a heart attack or stroke, but there is good evidence to suggest that they may actually be harmful. In a re-analysis of unpublished data from two landmark studies in the 1960s, the Sydney Diet Heart study and the Minnesota coronary experiment, revealed that cardiac patients who swapped butter for vegetable oils had increased risk of death despite lowering cholesterol.

Contrary to popular belief, for most frying purposes extra virgin olive oil is fine.

Furthermore, when these oils are heated to high temperatures they release toxic compounds known as aldehydes that are strongly linked to cancer, heart disease and dementia. Professor of bioanalytical chemistry and chemical pathology Martin Grootveld has done research that reveals that a typical meal of fish and chips fried in vegetable oil contained 100-200 times more toxic aldehydes  than what is recommended as a safe daily limit by the World Health Organisation.

I personally follow my own advice and cook in ghee, butter or  coconut oil  as these oils are stable and safe when heated to high temperatures, and contrary to popular belief, for most frying purposes extra virgin olive oil is fine too.

Coconut oil - healthy or not?

Incidentally, the recent declaration by the American Heart Association that  coconut oil is unhealthy due to its saturated fat content  is scientifically shaky as the totality of the evidence in relation to saturated fat and cholesterol has been disregarded. There's a public fear of saturated fat and cholesterol, and many companies and organisations have a vested interest in maintaining the status quo. For instance, American investigative journalist Nina Teicholz uncovered one association in questions that  "has long received major financial support from the vegetable oil industry".

Olive what they’re having

As for extra virgin olive oil, just what makes it such a healthy choice? For starters it’s high in beneficial compounds that have anti-inflammatory properties, polyphenols, and it improves the function of HDL (good cholesterol) in the blood stream. It’s the common denominator base fat that spans all across the Mediterranean countries which have traditionally had a low incidence of heart disease. A landmark Spanish government sponsored study (PREDIMED) revealed that middle aged men and women who consumed a Mediterranean diet  supplemented with at least four tablespoons of extra virgin olive oil daily had a 30 per cent relative risk reduction in suffering a heart attack, stroke or death within five years in comparison to those advised to follow a “low fat” diet. For every 61 individuals adopting the higher fat extra virgin olive oil diet, one stroke was prevented.

So next time you’re in the supermarket and tempted to buy that “low fat”, “heart healthy” or “proven to lower cholesterol” food product, opt for butter, ghee, or extra virgin olive oil instead. Your waistline, taste buds, and heart will thank you for it.

The Pioppi Diet  by Dr Aseem Malhotra and Donal O'Neill is published by Penguin Michael Joseph £8.99

Follow Dr Malhotra on Twitter  @DrAseemMalhotra