On the Table

The latest diet fad: 5-2 fasting

CorrespondentMarch 12, 2013 

The next big diet fad may be here.

It’s from Britain, where a best-selling book, “The Fast Diet,” advocates intermittent fasting. Some call it alternate day fasting or a 5-2 plan, meaning you eat what you want to for five days each week and restrict for two.

You can mix the two fasting days into the week wherever they best fit your schedule or social plans.

Nutritionists often discourage fasting. One rationale is that skipping meals may make you so hungry that you’ll lose control and overeat later. Skipping breakfast may also make it difficult to concentrate at school or work.

On the other hand, fasting forces your body to use fat stores for energy, and some reports link intermittent fasting with better heart health.

In fact, the evidence pro or con for fasting is spotty. That said, fasting is also nothing new.

Intermittent fasting has been practiced in some religions since ancient times. And my co-worker Jim – I’ve written about him before – has been fasting for 24 hours twice a week for years and finds it helps him, a former Marine, stay fit and trim.

I practice daylong fasting, too, at times and find it effective and efficient. In fact, it makes me feel great – light and energetic.

Fasting runs the spectrum from total fasting – only water – to restricting yourself to very light meals or snacks. In “The Fast Diet,” fasting days include a couple of light meals – 250 to 300 calories each – per day.

That’s still about 1,000 fewer calories than most people eat each day. If you do that twice a week and don’t overeat on the other days, the calorie deficit should help you lose weight.

If you have diabetes, an eating disorder or other medical condition, check with your doctor before making diet changes.

Fasting is easier for some people than others. Side effects of daylong fasting may include headaches, bad breath, edginess, fatigue and, not surprisingly, hunger.

When I fast and my rumbling stomach bothers me, I eat a piece of fruit or a couple of lemon drops to get by. Whether you skip or skimp on food, do what works for you.

Fasting isn’t for everybody, but it works for some. Ultimately, any diet for weight control has to be something you can sustain – healthfully – for the long run.

Suzanne Havala Hobbs is a licensed, registered dietitian and clinical associate professor in the Departments of Health Policy and Management and Nutrition in the UNC Gillings School of Global Public Health. Send questions and comments to suzanne@onthetable.net; follow her on Twitter, @suzannehobbs.

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