About 20 years ago, I began my school day by teaching a group of eighth graders that contained four girls who were close friends, sat close to my desk, and were not only impressively intelligent but also rather well-behaved. They approached eighth grade English like a grad course where an "A" equaled a pay raise, and I never had to worry about them talking or giggling or failing to pay attention.

Except on certain days after Christmas vacation. They changed. Really changed. They whispered. They giggled. Their minds seemed to stray.

After one such episode, I asked after class what was causing the occasional out-of-character behavior. Their heads bowed. They sneaked glances at one another.

"We go to Missy's house to wait out the two-hour delays," one of the girls explained. "And her mom has a cappuccino maker."

So instead of these prim and proper girls entering my room with their bodies doing what they normally do, processing a mixture of carbs and fat and protein from a typical breakfast, chugging cappuccino during a two-hour delay meant sugar and caffeine and little else was coursing through their veins. And they weren't the same.

It was as plain as day.

But the accepted research at that time said, nay, that there was no correlation between hyperactivity in kids and sugar and caffeine in their diets.

I started paying closer attention to all behavior after a two-hour delay.

Many of the kids who normally struggled to stay focused after lunch were now that way by ten o'clock. The later start was probably allowing many of these kids to eat the junk that they normally consumed at lunch before they left for school.

The behavior changes during a two-hour delay combined with the numerous stories parents told me throughout the years linking middle-school misbehavior and diet led me to believe the research was wrong.

The old research, that is.

The most recent research led by Jeanette Ickovics, director of CARE, Community Alliance for Research and Engagement at the Yale School of Public Health and published in the February issue of Academic Pediatrics has found what seemed so obvious to teachers and parents for years: sugar and caffeine, especially together, clearly affect the mental workings in children.

In this study, researchers surveyed 1,649 middle-school students from a single inner-city school in Connecticut to ascertain how many and how often sugar-sweetened drinks, including energy drinks were consumed. Not only did the researchers find a correlation between the amount of sugar-sweetened beverages consumed and the increase in hyperactivity and inattention, but they also discovered the correlation intensified when the sugar-sweetened beverages were energy drinks.

As a result, the published paper supports the recommendation made by the American Academy of Pediatrics for parents to actively limit their children's consumption of sugar-sweetened beverages and to not permit the use of energy drinks.

One alarming side note of the study is that the overall average of daily sugar-sweetened beverages for the 1,649 randomly selected middle-school students was two, with a number of individuals averaging seven such beverages a day.

Considering that most sugar-sweetened beverages contain between 100 and 150 calories of pure sugar (often in the form of high-fructose corn syrup) and that the rate of overweight children and teens has roughly tripled since the 1970s, the aforementioned recommendation seems sensible.

Lisa Powell, spokesperson for researchers at the University of Illinois at Chicago, and her colleagues have found another dietary element to partially explain the extra pounds now found on too many children and teens. By using data gathered in the National Health and Nutrition Examination Survey of 2009 and 2010, the researchers found that kids consume significantly more calories on the days when one of the foods consumed is pizza.

For those between 12 and 19, the extra averages 624 extra calories, which is about 25 percent more calories than an average non-athletic girl would need to maintain her weight and about 15 percent more than an average athletic boy probably needs.

The 408 additional calories consumed by children between 2 and 11 on days they eat pizza may be even more troubling considering that the average child between those ages requires significantly fewer calories than the typical 12-to-19-year-old adolescent.

Moreover, the 408 extra calories are not necessarily the amount over what's needed to maintain a healthy weight, but in addition to the average day's consumption, which is often already a few hundred more than optimal for too many youngsters.