If you're no stranger to dieting trends, perhaps you've come across the recent fad for fasting and extremely low calorie "cleanses." But there are plenty of reasons to be wary of fasting as a long-term weight loss strategy.

First of all, while even a day of fasting may indeed show you a big loss on the scale, this drop will be primarily water weight, which is guaranteed to come right back the moment you start eating again.

Weight loss during fasting also often comes from muscle rather than fat, which will ultimately lower your metabolic rate and interfere with your fitness progress. Additionally, fasting can put your body into "conservation mode," lower your levels of mood-boosting neurotransmitters, and cause a higher level of stress hormone cortisol, leading to cravings and metabolic problems and leaving you exhausted and irritable.


The psychological and physical challenge of fasting also means that it is incredibly hard to stick with, leading to a high drop-out rate among dieters who attempt fasting as a weight loss strategy. Frequent fasting can also lead to unhealthy eating habits on non-fasting days, a distorted attitude towards food, and in extreme cases even binge eating or bulimia.

Though proponents of fasting claim that it can help your body remove toxins, it's important to bear in mind that your body already has plenty of built-in mechanisms for cleaning your system. Other touted benefits of fasting, like lower blood pressure, increased insulin sensitivity, or reduced risk of chronic diseases, could be obtained much more safely and sustainably from simply eating a healthy diet; plus, most of these claims rely on results from animal rather than human studies.

Yet the risks of fasting are all too real. While fasting, you may experience dizziness, diarrhea, headaches, heartburn, fainting spells, low blood sugar, muscle aches, weakness, and fatigue.

Prolonged fasting can also lead to anemia, a weakened immune system, liver and kidney problems, irregular heartbeat, and vitamin and mineral deficiencies. The laxative and enema use encouraged on many "cleanses" can also lead to dehydration and fluid imbalances.


Fasting can be especially dangerous if you are pregnant or breastfeeding, elderly, diabetic, under 18, or recovering from surgery. You should also avoid fasting if you have gout, liver or kidney problems, a history of cardiac arrhythmias, or a history of eating disorders. Fasting can also interfere with the effects of certain medications.

Yet the biggest danger of fasting as a weight-loss strategy may simply be that it stops you from adopting a plan like ours that's actually healthy and effective. Most experts agree that a diet that features wholesome food and adequate nutrition is far better for you and your weight loss than a few quick-fix days of fasting.

However, a very occasional fast of 24 hours or less, like the few hours without eating we recommend on our steak stall day, fasting before a medical procedure, or fasting for a religious holiday like Yom Kippur, is unlikely to have any serious repercussions. But as the tortoise and the hare so long ago learned, for long-term weight loss, slow and steady wins the race!

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