Updated 02 December 2013

7 surprising diet myths

We highlight a few popular myths and surprising facts you may not have known about weight loss.


Weight loss. There seems to be no other area of human interest that generates more myths and more bizarre theories. And, in an eager attempt to shed a few kilos, we often pay too much attention to what marketers and self-appointed 'gurus' have to say.

If you're confused about what to believe, and what not, rest assured: there are safe and effective ways to lose weight; it's merely a question of separating the corn from the chaff.

Check out the slideshow on how to speed up your metabolism. And that's for real.

But now we highlight a few popular myths and surprising facts you may not have known about weight loss:

Myth #1: The more water you drink, the more weight you'll lose. Drinking copious amounts of water, at temperatures ranging from icy to boiling, will speed up weight loss.

Having a reasonable liquid intake of approximately 2.5 litres a day is an excellent idea for adults, but this doesn't mean that you should literally drown yourself by drinking 7 litres of water every day in addition to your intake of other liquids like tea, coffee, fruit juice, cold drinks, etc.

Excessive liquid intake can result in a condition called ‘electrolyte imbalance’, where your reserves of potassium and sodium are depleted to such an extent that you may develop water intoxication. Ironically, one side effect of electrolyte imbalances is that you may retain water and thus weigh more, even if you're losing fat.

Myth #2: Herbal slimming products are safe because they're ‘natural’.

Just because a slimming product contains herbs instead of pharmaceutical compounds doesn't mean that it's safe or that it will help you achieve weight loss. Always keep in mind that there are many herbs that are highly toxic and that you may poison your system by using these products.

A good rule is to do an internet search for the herbal components of your slimming products before you buy them, to check on their potential side effects and then to heed the warnings that reputable websites list for seemingly innocuous herbs.

Myth #3: Eating carbohydrates makes you fat.

This is really an amazing statement. Carbohydrates, including sugar, contain 16kJ (4kcal) per gram. If they contain dietary fibre, their energy content is even further reduced.

Fat, on the other hand, contains 37kJ (9kcal) per gram – a whopping difference. So if you approach dieting logically, it makes more sense to reduce your fat intake and to continue eating high-fibre carbohydrates.

Myth #4: A high BMI (body mass index) always means you should lose weight.

The BMI is just a handy tool that permits you to judge a person’s weight. But it doesn't always mirror an individual’s body fat content. For example, strength athletes like body builders may have very high BMI values, without being fat, because their bodies consist of pure muscle.

The BMI is often also not accurate when used for the elderly. It has been suggested that, in persons older than 65, upper arm measurements should be used instead to measure body weight.

Myth #5: Weight loss is always desirable, no matter what method you use.

This isn't true at all. If you use starvation or unbalanced diets that exclude whole foods groups or expose you to the risk of high fat intakes (i.e. variations of the Atkins diet), you may lose some weight, but at an unacceptable cost to your health.

Starvation diets can cause vitamin, mineral and protein deficiencies and strain your heart. Highly unbalanced or crash/fad diets can also cause deficiencies or expose you to unacceptably high intakes of total fat, saturated fat and cholesterol (high-fat, high-protein diets), renal problems, bad breath and constipation.

The endless variety of slimming pills and potions mentioned above are also not a good idea. In addition, rapid weight loss brought on by starving yourself or existing on proteins only, is usually unsustainable in the long run and can result in you regaining all the weight you have lost, plus additional weight, so that you land up in the vicious cycle of yo-yo dieting.

Then there is the danger of perpetual slimmers falling into the trap of anorexia or bulimia or even orthorexia. Losing weight can become an obsession that can ruin your health and your life. Rather stick to a sensible approach to weight loss by using a balanced, energy-reduced diet and exercise.

Myth #6: Overweight is always bad for your health.

Individuals who are a few kilograms heavier than they should be, are not necessarily less healthy than their slimmer counterparts, particularly if they're fit and do plenty of exercise.

Although researchers have not yet come to a final decision about the question of being “fit and fat”, there's no doubt that if you're moderately overweight and exercise every day, you may well have a stronger cardiovascular and respiratory system than a skinny couch potato.

The risk associated with being overweight also depends on where fat is stored in the body. Pear-shaped people with fat depots on their hips, buttocks and thighs (usually women) tend to have a lower risk of diseases of lifestyle than individuals who have fat depots in their abdominal areas (usually men with ‘beer boeps’ and women after menopause).

Furthermore, overweight or obese people with fatty liver deposits are also believed to be exposed to a greater risk of diseases than fat people without liver involvement.

Myth #7: Being thin is always good for your health.

This is certainly not true, because patients with anorexia and other eating disorders can develop life-threatening conditions such as heart and renal failure, or permanently damage their capacity for reproduction.

If you have dieted yourself into scarecrow mode, your body will probably also have few reserves left to fight infections and your immune system will be functioning at a sub-optimal level, which will make you particularly vulnerable to H1N1 and TB.

To function properly, your body needs an adequate energy supply, otherwise you'll always be exhausted and your brain, which requires a constant supply of glucose to function properly, won’t be able to cope. So make sure that even when you're attempting to lose weight that you still have a good supply of energy available in the form of carbohydrates (the body’s preferred fuel).

(Dr I.V. van Heerden, DietDoc, updated April 2011)

Any questions? Ask DietDoc

(Charlton KE, Rose D (2001). Nutrition among older adults in Africa: the situation at the beginning of the millenium. Journal of Nutrition, Vol 131:2424S-2428S; accessed on 23/08/2009)


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