Updated 28 January 2014

Why fad diets flop

Fad diets may promise you wonderful results, but these could cause more harm than good. Here's how to recognise them.


Read about a slimming diet that promises to make you lose 5kg in five days? Beware: this is a fad diet.

The human body isn't geared towards losing real weight derived from fat in such a short time. Human metabolism has its own clock and any diet that promises you a loss of more than 0.5 to 1kg in seven days, is having you on.

Yes, you may see your weight going down rapidly during those first few days, but if you're just losing water, you'll pick up all those kilos again the minute you stop following the diet.

What's more, one also tends to regain all the weight you've lost in record time and often shoot up to a new high. This type of slimming diet can easily trap you in the snare of "yo-yo dieting", paving the way to perpetual dieting and problems with your metabolism.

Unbalanced food intake

Beware of fad diets that tell you to eat only one category of food, e.g. only protein or only fruit. Fruit and vegetables are packed with antioxidants, vitamins, bioflavonoids, dietary fibre, and protective nutrients, but if you only eat fruit and vegetables to lose weight, you'll be doing yourself harm in the long run.

A two-to-three-day cleansing diet based on fresh, raw fruit and/or vegetables, is perfectly acceptable -provided you don’t try and carry on with this type of diet for weeks on end. If you do, you may lose weight, but will be in danger of developing all kinds of deficiencies. Fruit and vegetables are deficient in many important nutrients such as protein, iron, calcium, vitamin B12, and the essential omega fatty acids.

The same goes for protein-only diets - you simply won't be getting all the nutrients you need.

To remain healthy and lose weight, you need to eat a mix of foods, not just one category. If you hear of a diet that tells you to cut out all protein, all carbohydrate or all fat you should know that it's not balanced and that it can lead to all kinds of problems.

Even a low-fat diet, which is one of the most successful diets for losing weight, still has to contain some healthy fats to provide the essential fatty acids your body requires.

Starvation diets

Very low energy diets are sometimes used to treat people suffering from gross obesity. In general, this type of diet should only be used under the strict supervision of a medical doctor and a clinical dietician.

If you're given a slimming diet which restricts your food intake to a few lettuce leaves and the odd tomato, and you get so hungry that your head spins and you feel faint all the time, then know that this is a fad diet.

You may lose weight on this kind of diet, but you won’t be able to carry on with it for very long. And once you stop, your body will go into overdrive to try to restore its normal balance. Having received the message that the food supply has been cut off, your body will try to conserve energy, slow down weight-loss processes and start storing fat.

Believe it or not, most people lose weight most efficiently when they're not starving, but eating a balanced, low-fat, high-fibre diet which lets them feel comfortably satiated.

Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Read more of her articles.


Read Health24’s Comments Policy

Comment on this story
Comments have been closed for this article.

Live healthier

Exercise benefits for seniors »

Working out in the concrete jungle Even a little exercise may help prevent dementia Here’s an unexpected way to boost your memory: running

Seniors who exercise recover more quickly from injury or illness

When sedentary older adults got into an exercise routine, it curbed their risk of suffering a disabling injury or illness and helped them recover if anything did happen to them.