New diet book says key to weight loss is managing blood sugar

NEW YORK CITY, N.Y. (WPVI) -- A new book "The Prescription Diet," details how measuring your blood sugar is the key to losing weight.

And the researchers behind the book say shedding those extra pounds starts with accepting that there's no one-size-fits-all solution.

"For years, we've been trying to search for that silver-bullet diet that would work for everybody. And we've been miserably failing," says Eran Segal, of Israel's Weizmann Institute of Science.

"And that's because the best diet for each person really has to be tailored to that individual," Segal adds.

Segal co-authored the book with his research partner at Weizmann, Eran Elinav.

They originally wrote their theories under the banner The Algorithm Diet for scientific journals, however, it's been published in the popular press as The Personalized Diet.

Segal and Elinav say the key is in watching how your blood sugar reacts to different foods.

For example, too much sugar in your system gets stored as fat.

They say they made their discovery after testing blood sugar levels in 800 people after every meal for a week - 47,000 meals.

And the findings were dramatic.

"What we were really surprised to find is that different people react very uniquely, even when they eat the same exact food ," says Elinav.

Foods that created a healthy response in some participants produced unhealthy blood sugar spikes in others.

To get results, they say you have to be willing to suffer a little pain, pricking your finger after meals to see what makes your blood sugar levels soar.

Segal and Elinav say their algorithm will determine what foods you should avoid.

"We've been taught that we should steer clear from the white bread, go for the wheat bread, but not always?" asked ABC's Erielle Reshef.

"What we were surprised to find out was just like any other food, there is no such thing as-- a good bread. The response to bread was completely individualized," noted Elinav.

And what about foods to ADD to your diet.

For some, smearing bread with fats like avocado, olive oil, and in some cases, butter, can help normalize blood sugar.

And for athletes, a mind-blowing food bust - pre-workout bananas and dates could be doing you in, causing more fatigue.

But there are foods the doctors say are less likely to cause crazy blood-sugar spikes, such as meats and cheeses.

"I never met a cheese I didn't like," notes ABC's reporter.

"When you don't have carbohydrates, those foods will not spike your blood sugar levels," says Segal.

Wnich is why the researchers say traditional low-carb programs may work in the short term, but may not be sustainablde.

"Our solution gives you a way to find out which carbohydrates would actually be best for you to integrate into what we believe would be a healthy diet for you," says Segal.