With the start of a new year comes the age-old resolution to lose weight, and more often than not the goal is to shed the kilos fast.
Crash diets come with the promise of "a new you in no time" and according to the experts, it may deliver – but not without some serious health risks. This is because most of these diets require fasting and the elimination of virtually all carbs.
Read: Fad diets are hard work but can deliver
Why rapid weight loss is not really weight loss
If you think you're dropping 5 kilograms of fat in just 5 days, think again! Dr Ingrid Van Heerden, a registered dietician and also Health24's DietDoc, says that the human body isn't geared towards losing real weight derived from fat in such a short period of time.
She explains that although the scale may show your weight dropping rapidly while on a crash diet, it is likely that you are just losing water, in which case you will pick up all those kilos again once you stop the diet. "This can easily trap you in the snare of 'yo-yo dieting', paving the way to perpetual dieting and problems with your metabolism," she says.
Nutritional deficiency: putting your muscles at risk
Fad diets often fail at providing nutrition from all the food groups, meaning that you’ll be more susceptible to illness, dizzy spells and lethargy.
Excluding certain foods from your diet may just be defeating the purpose of becoming healthy. For example, carbohydrates are one of the first food groups to be cut from one's diet when trying to lose weight fast on a "quickfix diet". This could be bad news for any person wanting to exercise, as energy balance studies have shown that carbohydrates are by far the best source of energy or "fuel" for physical activity and to maintain our Resting Energy Expenditure (REE).
Read: Why you need carbs
Your body relies on three main sources for fuel: carbohydrates, fat and muscle. Crash diets do not allow much fat or carbohydrates, which means that eventually your body will use muscle to sustain itself, especially if you exercise and follow a crash diet over an extended period. This may actually ruin weight loss efforts because muscles help you burn more calories even when you are at rest.
Although detox diets are also touted as a way to lose weight quickly, DietDoc advises that it is better to rather follow a short detox plan and to change your lifestyle to ensure sustained and healthy weight loss. She recommends a quick 2-day detox plan.
Read: Detox: fact or fiction?