As a paediatrician, I love goofing around with my patients. I often start visits with younger kids by asking for a foot rub. I do this to make visits more fun (and less scary) and to give my patients "permission" to act silly. As a result, parents often say things such as, "He hasn't been this wild since he had a sugar high at a birthday party last week."
Many parents think sugar makes kids hyper. It doesn't. Lots of scientific studies have been done to answer the question, and they have all reported the same thing: Sugar does not make kids overactive.
Given how well parents know their kids, how can those studies be true?
The answer lies in the clever way doctors examine how sugar affects behaviour.
Doctors take a bunch of kids who are similar in age, background and other factors. Then they divide the kids into two groups. One group gets a regular diet, and the other gets the same diet with extra sugar hidden in the food so it can't be tasted. No one - not the kids, the parents or the doctors - knows which kids got which diet. A special code is used so the results can be evaluated after the study is completed.
This type of research, which is called a "double-blind" study, prevents the subjects and researchers from having an unconscious bias - or a tendency they're not aware of - affect the results.
But if sugar doesn't make kids hyper, why do parents believe it does? The explanation lies with two assumptions parents make. First, kids get lots more sugar in the form of cake, ice cream and sodas at special events such as birthday parties. Kids love birthday parties not just because of the goodies but also because they get to play with their friends in a fun environment. It's largely the party atmosphere that makes them hyperactive, not the sugar.
The other factor is that parents have been blaming wild behaviour on sugar for decades. I bet your grandparents said the same thing to your mum and dad when they were kids. The repetition of the theory over a long period of time makes it believable.
What happened with sugar is similar to the belief that kids will catch a cold if they go outside with wet hair on a chilly day. This has also been shown not to be true, but lots of people still believe it.
Now comes the bad news: Even though sugar doesn't make kids hyper, that does not mean it's good for you.
Sugar tastes good but has no nutritional value. That means it doesn't help you grow or stay healthy. Too much sugar can change the way you think food should taste. A ripe banana or a juicy orange can't compare to a KitKat bar in terms of sweetness. If kids (and adults) eat too much sugar, they may reject healthful foods as not being sweet enough. Eating too much sugar replaces healthful foods in your diet and increases the chances that you will become overweight. Excess sugar intake is also associated with diabetes and heart problems later in life.
The food industry knows people crave sugar, so they add it to lots of foods. As a result, you may not be aware of how much sugar is in your diet. Many popular brands of yoghurt contain 20 grams or more of added sugar.
So the next time you want a snack, do your body a favour and reach for an apple or a handful of strawberries instead of a box of chocolate chip cookies.
Bennett's book The Amazing Human Body will be published in 2017.
The Washington Post