Crash diets: How they work

There is an upcoming wedding or event where looking good is imperative and you need to dress your best and fit into the desired clothes. You are desperate. What do you do? You turn to crash diets to get into shape in a short time.

Do crash diets work? Yes they do let you lose weight quickly. It is the quick fix answer for those looking for an easy way out to their weight issues. It is guaranteed though temporary weight loss especially for those trying it for the first time.

Unfortunately that’s all there is to it because, crash diets make you pay a huge price for this make-believe weight loss by compromising on health. Being on a crash diet is stewing a cauldron of unhealthy behaviours and ill effects.

Let us take a look at the side effects of crash dieting.

Puts back extra weight:
If you can cause a deficit of 1000 kcal a day, then in 7 days you will theoretically reduce one kilo. Anything beyond this constitutes a very low calorie diet and has ill effects. This is what crash diets do. They give you so less calories that you reduce your weight too quickly.

But what they do not tell you is that you can also put back the weight even faster than it took to lose. Once you have punished the body by putting it through a sudden lack of food it tries to conserve calories. This is part of any animal’s survival instinct. That is why once you have stopped the crash dieting you find all the weight you lost bouncing back with some extra kilos added on.

Loss of muscle:
25% of the body weight is muscle. Since crash diets lack enough carbohydrates, body uses proteins for energy. Also, when you suddenly lose a lot of weight through only diet and no exercise, you also lose a lot of muscle. This is in no way acceptable to the body’s mechanism. It responds by hunger pangs and cravings, making you binge.

Lack of essential nutrients:
Most crash diets do not include a healthy balance of foods. Because it is difficult to include recommended amounts of vitamins and minerals is a diet lesser than 1200 kcal. This means not only do you lack in proteins, carbohydrates, essential fats, but also in vitamin and essential minerals.

You feel weak due to muscle loss and protein levels fall. Crash diets cause loss of hair, dry scalp and skin, anaemia, lack of concentration, headaches, dizziness, fainting, nausea, psychological problems like depression, irritation, short temper, dark circles, bad breath and flabby skin.
In what way can you look good with bad hair and skin and a nasty temper?

Unhealthy blood profile:
When you crash diet your blood tests show raised triglycerides, uric acid and cholesterol due to rapid breakdown of fats and proteins. Those who already have these issues are in for more ill health. If you have gout then crash diets will induce or aggravate the pain.

Abnormal diet menus:
Crash diets may be a fruits-only or liquids-only diet, or a one meal a day diet. It is in no way similar to what you eat on a daily basis or what the rest of your family members eat. If so, how long can you keep to this kind of eating? One day you will have to return to your social ways and then what happens?

Yo-Yo effect:
Crash diets are short-term plans. So you tend to go on it several times. The more number of times you have been on a diet to lose weight, the more difficult it gets to reduce the next time. The single most ill effect of crash diets is that the yo-yoing of losing and increasing ultimately leaves you with zero weight loss and low metabolism.

Is it okay to reduce weight fast? Some situations may demand a quick weight loss like a pending surgery. Then it is okay to reduce weight quickly, but within the scope of eating correctly. The most effective weight loss strategy is diet assisted by exercise. Theoretically if you are now eating 3000kcal a day, then reducing food intake by 1000 kcal/day and burning up another 500 kcal through exercise will lead to a weight loss of 6 kg a month.

Temporary diets do not change your eating habits. The longer you stay on a healthy diet, the longer that way of eating stays with you until it becomes a habit. Short courses of dieting do not teach you permanent behaviours. It only teaches you to misbehave with food.

Parvathy R Krishnan

The author is a trained Nutrition & Dietetics expert with over 20 years’ of experience in hospitals like Vijaya Hospital in Chennai and the Armed Forces Hospital and New Mowasat Hospitals in Kuwait. She is presently a member of the Research Society for the Study of Diabetes in India. Parvathy blogs at

More by this author:

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Dieting tips for those at work

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