To control overeating: Slow down!

Eating slowly might help teens maintain a healthy weight, a new study finds. “We often rush through the day and gobble down meals without fully enjoying them,” says Pedro Cabrales, one of the study’s authors. “A simple yet powerful change in our lives is to eat slower and stop eating when we no longer feel hungry.”

Cabrales works at the University of California in San Diego. He and his colleagues described their findings December 15 in Pediatric Obesity.

About 17 percent of U.S. children and teens are obese — extremely overweight. People with obesity have a higher risk of type 2 diabetes, heart disease, stroke and other illnesses. Eating too fast is one likely contributor to obesity among teens, Cabrales says. It takes 10 to 12 minutes for the brain to realize the stomach is full, he notes. By eating too fast, teens can easily take in too many calories before their brain realizes the body has had enough.

Many children and teens likely eat too fast because they don’t know about healthy eating habits or because they’re distracted by activities like watching TV, notes Danelle Fisher. She’s a pediatrician at Providence Saint John’s Health Center in Santa Monica, Calif. She also was not involved in the new study.

As a bioengineer, Cabrales tries to find practical solutions for biological problems. For their new study, his team studied 78 adolescents in Mexico. All were between the ages of 12 and 15.

The researchers split the kids into two groups. One group of 36 acted as a control. In this case, it means they were given no special instructions and simply ate as they normally had.

The other 42 volunteers formed the treatment group. The researchers gave each of these participants a 30-second hourglass timer. Its purpose was to remind the participants to eat slowly. The researchers told the teens to flip the hourglass after each bite and to not take another bite until the sand ran out of the hourglass.

Teens in the treatment group also were given information about obesity and guidelines for healthy eating. Those guidelines included eating healthy home-cooked meals at the table, drinking water before eating and avoiding drinks with added sugar. Teens also were urged not to take second helpings, to overfill their plates or to snack between meals.

Slower eaters lost weight

One year later, the researchers weighed the teens and asked how often they had used the hourglass while eating. Of the 42 who were given dietary guidelines and an hourglass, 14 said they used the hourglass regularly for at least half the year. Another 18 did not use the hourglass often, if at all. (The rest graduated or moved away before the study was over, so their behavior was not measured.)

On average, by year end, teens in the treatment group who used the hourglass as instructed lost 3 kilograms (6.6 pounds). That came to about 4.5 percent of their body weight. Those who didn’t use the hourglass gained an average of 7 kilograms (about 15 pounds) — an increase of 13 percent. Teens in the control group gained almost as much — an average of 5.9 kilograms, or about 11 percent.

These results seem to suggest using the hourglass as a reminder to eat slowly helped teens lose weight.

But may not be that simple, warns Yoni Freedhoff of the University of Ottawa in Canada. He’s a doctor who treats patients with obesity.

“The only thing that was measured was the use of the hourglass,” Freedhoff points out. Teens who used the hourglass to eat slowly might also have been more likely to follow the other instructions too. Freedhoff says there is a “very real and likely probability” that following some or all of the other dietary guidelines explained the lost weight.

Also, teens who used the hourglass and lost weight had started out heavier, on average, than the kids who gained weight. So some teens in that treatment group may have been more motivated to lose weight in the first place, says Geert Schmid-Schoenbein. He is another bioengineer on the study who works at the University of California, San Diego. Some teens whose parents were obese, he recalls, told their pediatricians: “We don’t want to become like our parents.” Those teens might have been more likely to use the hourglass and to follow the other guidelines.  

Schmid-Schoenbein says his team needs to do more studies to find out which pieces of advice and which behaviors help most. For now, he says, the important thing is that teens eat slowly enough to notice when they are full.

Power Words

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adolescence    A transitional stage of physical and psychological development that begins at the onset of puberty, typically between the ages of 11 and 13, and ends with adulthood.

bioengineer    Someone who applies engineering to solve problems in biology or in systems that will use living organisms.

calorie  The amount of energy needed to raise the temperature of 1 gram of water by 1 °C. It is typically used as a measurement of the energy contained in some defined amount of food.

control  A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that give scientists something against which they can compare their experimental data.

obesity  Extreme overweight. Obesity is associated with a wide range of health problems, including type 2 diabetes and high blood pressure.

overweight   A medical condition where the body has accumulated too much body fat. People are not considered overweight if they weigh more than is normal for their age and height, but that extra weight comes from bone or muscle.

pediatrics   A field of medicine that has to do with children and especially child health. A doctor who works in this field is known as a pediatrician.

stroke (in biology and medicine) A condition where blood stops flowing to part of the brain or leaks in the brain.

treatment   A part of an experiment where there is some kind of change from normal conditions. For example, if scientists were testing the effect of a drug on patients, people who received the drug would form the treatment group. A scientific study can have multiple treatment groups, which may be compared with one another. Often, studies also include a condition where there is no change from normal conditions (see control group).

type 2 diabetes   A disease caused by the body’s inability to effectively use insulin, a hormone that helps the body process and use sugars. Unless diabetes is controlled, a person faces the risk of heart disease, coma or death.