Diet myths that make you fatter and sicker are plentiful, says UK public health researcher Dr Zoë Harcombe. 

Many dietitians say that all you have to do to lose weight is eat less and exercise more. They also say you must avoid saturated fat like the plague because it clogs arteries and causes heart disease.

And that meat is bad, carbs are good and you should eat at least 5-a-day fruit and veg.

Those myths make dietitians increasingly irrelevant. They also contribute to the obesity, diabetes and heart disease epidemics across the globe, says Harcombe. She demolishes myths in her brilliant e-book, 20 Diet Myths – Busted. Scroll to end for details on where to get it. Here, she gives 10 of those myths in bite-size pieces – Marika Sboros

By Zoë Harcombe*

Myth No 1: Energy in equals energy out

Diet advisors love to say “energy in equals energy out”, and “you can’t change the”laws of the universe.” They clearly don’t know what the laws say. There are four laws of the universe. None says energy in equals energy out. Two laws can be ignored by the dieting world. Two need to be taken into account. The first essentially says energy can be changed from one form to another.

The second notes that energy will be lost during the process of energy changing form (we boil the kettle, electricity heats the water and steam is lost in the process.) These “laws of the universe” are about energy, not weight. They were never intended to become fundamental principles of dieting. They have some relevance to dieting, but only when correctly applied, and when all the caveats are allowed for.

The first essentially says energy can be changed from one form to another. The second notes that energy will be lost during the process of energy changing form (we boil the kettle, electricity heats the water and steam is lost in the process.)

Dr Zoe Harcombe

Dr Zoë Harcombe

 Myth No 2: Eating less will make you weigh less

Eating less will not make you weigh less. It is an almost universally held belief that people who are overweight just need to eat less and/or do more. The idea is based on so many underlying assumptions – none of which is true.

The idea that if you eat 500 fewer calories the body will give up 500 calories of fat to make up the difference is the ultimate naivety in the world of dieting. The body is not a cash machine for fat.

Myth No 3: Doing more will make you weigh less

Doing more will not make you weigh less. Both the eating less and doing more beliefs make the massive and wrong assumption that the body is able to burn fat. The body can only burn fat when there is no glucose/glycogen available. Modern man rarely, if ever, allows his body to get to the state where it can burn its own fat – let alone will.

Myth No 4: Weight gain is the result of too many calories in

Weight gain is from fat being stored, not too many calories in. Equally, weight loss is about fat lost, not fewer calories in. The perfect way to store fat is to eat carbohydrates. It’s the carbs that count, not the calories.

Myth No 5: One pound equals 3,500 calories

One pound does not equal 3,500 calories. One of the most commonly held diet myths is: “To lose one pound of fat you need to create a deficit of 3,500 calories”. It is actually worse than a myth – it is one of the cruellest lies we have told desperate dieters.

The myth that one pound equals 3,500 calories is wrong at every level. You will see this formula in government literature, in just about every diet book, in private health booklets and all over the Internet. The next time you see it, or hear it, ask where it comes from. You will not get an answer.


Myth No 6: Cholesterol will kill you

Cholesterol is not the bad guy in any way, shape or form. You would literally die without cholesterol. It is a key part of the structure for every cell in your body. Cholesterol is so vital that your body makes it, and cannot risk leaving it to chance that you would get it externally from somewhere. Statins stop the body from producing the cholesterol – they literally stop one of your fundamental body processes from being able to function.

One in 500 people has familial hypercholesterolemia, and may have a problem clearing cholesterol in their body (rather like type 1 diabetics who can’t return blood glucose levels to normal). For anyone else to be actively trying to lower their vital and life-affirming cholesterol levels is deeply troubling.

There is no such thing as good and bad cholesterol. The chemical formula for cholesterol is C27H46O. There is no molecular formula for a good version or a bad version. We must stop using such erroneous and emotive terminology.

Obesity EpidemicMyth No 7:
 You need to eat 5-a-day fruit and veg

There is no basis for 5-a-day. The pick-a-number-a-day campaign (it is not always five in each country) has spread across three continents and tens of countries. It has become the most well-known and promoted public health nutritional message ever.

You would think, therefore, it was evidence-based and founded upon robust scientific knowledge. You would be wrong.

Five-a-day is a marketing campaign with no evidence; it is fuelling the obesity epidemic, rather than helping in any way whatsoever. If parents knew what researchers such as Dr Robert Lustig and Dr Richard Johnson know about fructose, they would never give children fruit juice again.

Myth No 8: Saturated fat causes heart disease

It does not. There are three facts I can state without any fear of being proven wrong: i) It has not been proven that saturated fat consumption causes heart disease; ii) It has not even been proven that there is a consistent association between saturated fat consumption and heart disease; iii) The definitive study to try to prove this has not been done and likely never will be.

Myth No 9: Fat clogs your arteries

Fat does not clog your arteries. If a juggernaut were travelling around the road transport system – which roads would clog up? The minor roads and country lanes would be impassable and the motorways would run with little disruption. Fat never clogs veins.

By a process of common sense, therefore, fat also never clogs arteries. It is a reasonable assertion that fat is not even travelling freely in the bloodstream. Fat and water don’t mix, so, since blood is effectively water, fat cannot travel freely around the blood system.

Fat travels around in lipoproteins – along with cholesterol, protein and phospholipids. The idea that fat somehow leaps out of lipoproteins to attach itself to the arterial wall to try to clog up the system and kill you is ludicrous.


Myth No 10: Graze – eat little and often: 

Do not graze, unless you are a cow or want to be the size of one! This (advice) seems partly because of the nonsensical idea that you can or should keep blood glucose level topped up. I know not why else this advice would be given because it is one of the surest ways to fatten humans (or grazing animals).

Harcombe demolishes other myths, among them:

  • Butter is bad, man-made-margarine is good – Do you really, honestly think man knows better than Mother Nature how to feed us? Or, do you think there are huge profits to be made in manufactured, hydrogenated, Frankenfoods, and that’s why a campaign has been waged against real food encouraging you to eat fake food instead?
  • Meat is loaded with saturated fat – Meat is mainly unsaturated fat. I have yet to find a meat on the planet with more saturated than unsaturated fat – and I’ve checked whale, quail, chicken, beef, lamb, goose and all sorts. If dietitians know this, why are they not telling us? Dare I suggest that it doesn’t fit with the advice: “Don’t have bacon for breakfast – have a (sugary) cereal instead?”
  • Fruit is highly nutritious ­– It is not; fruit’s benefit has been massively over-hyped. Those who have studied nutrition are not surprised that (eating more fruit) has no impact on cancer, and would be surprised if it had any impact on any modern health condition.
  • Fructose (fruit sugar) is good for dieters – It is bad for dieters, more likely to make them fat. Having established that fruit is not that nutritious, it gets worse. Fructose, also known as fruit sugar, is being called the fattening carbohydrate in the world of obesity. It is uniquely metabolised by the liver, so it doesn’t get the chance to be used up as fuel in the blood stream – it goes straight to the liver where it can be turned into fat.

Harcombe also says that the idea that man is naturally active is another myth. Man is as evolutionarily disposed to being sedentary as to gathering food, she writes. “What man would have done, and what we should do today, is natural activity – walk, talk, sing, dance, cook, clean and tend the land, not pump iron.”

*Dr Zoë Harcombe is a Cambridge University graduate, an obesity researcher and a qualified nutritionist with diplomas in diet, nutrition and clinical weight management. She works exclusively in the area of weight and obesity, and reads, writes and talks about obesity as many hours as possible, seven days a week. Her goal and drive are to reverse the obesity epidemic.

She has clear views on how it started and what is needed to stop it, documented in 2010 in The Obesity Epidemic: What caused it? How can we stop it?

*A full version of 20 Diet Myths – Busted by Zoë Harcombe is available for free download by clicking here