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Review: The 5:2 Fast Diet


By Katie Lewin


Are you the type of dieter who lives for cheat days? (Aren’t we all?) Then this diet may be for you. The basic premise of the 5:2 diet, or intermittent fasting as it’s often called, is that five days a week you can eat normal, balanced meals, like pasta or rice, with fruit and veggie sides (and the occasional sweet treat included!). The catch? The other two days you’re limited to just 500 or 600 calories (depending on gender) a day. A lowfat yogurt for breakfast, chicken broth for lunch, and a few gulps of air for dinner may not sound like enough to sustain someone. But the promise of five days of freedom just might be.

The Theory: By dramatically limiting calories on fasting days, the 5:2 diet claims that the body, needing somewhere else to turn for energy, will first target glucose and then stores of fat. From a more psychological perspective, its creators cite “zero boredom” as the secret to the diet’s success. “Since you are only fasting for two days of your choice each week, and eating normally on the other five days, there is always something new and tasty on the near horizon,” explains founder Mimi Spencer on the diet’s official website.

Pros: This diet could be a great choice for someone who’s intimidated by the prospect of staying disciplined 24/7. The promise of five days of normal, healthful eating could prevent the lapses that characterize more consistently restrictive diets. And the 5:2’s permitting of most foods on most days allows for a nutritional, well-balanced diet.  

Cons: Not surprisingly, the fasting days are rough. 5:2 dieters complain of irritability, bad breath, weakness, nausea, and difficulty sleeping on the days they abstain. And since eating is at the heart of so many social gatherings, intermittent fasting can even be isolating. In addition, diets that emphasize extreme calorie restriction can be dangerous and enabling for people who are vulnerable to developing eating disorders.  

Bottom Line: The 5:2 diet may work in the very short term, but don’t expect staying power. It’s unlikely that dieters will be able to incorporate fasting into their eating habits long term. This diet is not recommended for people who require consistent, substantial nutrition, including pregnant women, people with diabetes, children, or people recovering from surgery or eating disorders. 

Published January 5, 2015.  

Katie Lewin is a Bay Area-based health and lifestyle writer.  

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