This Cracker Test Can Help You Work Out How Well You Digest Carbs

Eating carbs makes you fat and sick. Case closed. Or at least that's what the most popular diets of the past few decades have told us. But the reality is a little more complicated.

Enter the so-called "cracker test," which is said to reveal how many starchy carbohydrates a person can eat without triggering excess weight gain—in a matter of seconds.

It's important to note that carbohydrates fall into three main categories: starch, sugar and fiber. Foods from milk to kale and potatoes contain a form of the molecule.

The Centers for Disease Control and Prevention recommends the carbohydrates we choose are those lower in calories, fat and sugar but high in water, fiber, vitamins and minerals. A stewed apple pie sprinkled with cinnamon rather than a doughy apple pie, for instance.

Moalem believes people who can break down starchy carbs quickly have ancestors who subsisted mainly on grains. Getty Images

The cracker test has made headlines recently after it was tested out on the BBC TV show The Truth About Carbs. It was made popular by Dr. Sharon Moalem, a geneticist based in the U.S. who wrote about it in his book The DNA Restart.

To try out the test, take three plain unsalted crackers and a timer, Moalem told The Times.

Place the cracker in your mouth, immediately begin chewing and start the clock. Then, note down the number of seconds it takes for the cracker to change flavor. If it doesn't change, note that down instead. Repeat twice more and divide the figure by three to calculate the average.

According to Moalem, the length of time it takes a person to detect a change will see them fall into one of three categories of recommended starchy carb intake: full, moderate or restricted. It all comes down to the concentration of a protein called amylase in our mouths, which helps to digest starch.

If the taste changes under in under 14 seconds, a person has a lot of amylase chopping up starch molecules into smaller sugar-like molecules. Such people likely inherited multiple copies of the AMY1 gene used to make amylase in the mouth and pancreas, as their ancestors may well have had a diet full of grains. This group can have up to 50 percent of their calories from carbs, 20 percent protein, and 30 percent from fats.

Those who take between 15 to 30 seconds fall into the "moderate" category. Their bodies take longer to break down starchy carbs and are advised to have up to 35 percent of their calories from this source, 30 percent protein and the remainder from fats.

And if the timer runs past the 30-second mark, your calorie type is "restricted," according to Moalem. That means no more than a quarter of daily calories should could from carbs, with 35 percent from protein and 40 percent from fats.

If this seems too good to be true, you're not wrong.

Aisling Pigott, qualified dietitian and spokeswoman for the British Dietetic Association told Newsweek: "there is no 'test' because processing of carbohydrate is an incredibly complex process."

"It is interesting that everybody responds differently, but this is not a definitive guide nor does it define 'carbohydrate digestion.' Digestion, weight and food tolerance is incredibly complex." The way our bodies break down carbohydrates is more complex than a single enzyme, stressed Pigott.

What is clear, however, is that carbohydrates shouldn't be demonized. Pigott added: "They are a necessary fuel for energy."

This piece was updated to include comment from Aisling Pigott.