Nov. 15, 1999 (Atlanta) -- Before you reach for that between-meal snack, consider this: a new study suggests that snacking will not only do nothing to curb the amount of food you'll eventually eat at the next meal, it could even contain the most fattening calories of the day.
French researchers came to this conclusion after studying the body's response to additional food intake in the interval between a decent-sized lunch and a buffet dinner. Eleven lean, young men participated in the study, which took place in four sessions over two weeks' time.
The first session was devoted to finding out how much the men ate of a given lunch, as well as how soon afterwards -- unprompted by a clock -- they were hungry enough to ask for dinner. During this interval, the researchers took frequent measurements of blood glucose and insulin concentrations to get a biological picture of how the men's bodies usually reacted to food intake and hunger.
During the next three sessions, the men ate identical lunches. The difference was, the researchers introduced a snack between lunch and dinner and the men had to eat it, regardless whether they were hungry.
To test for hunger during the lunch-to-dinner interval, the men were asked to report frequently whether they felt satisfied. And to make sure it was actually hunger and not habit, the men were kept in isolation during the sessions -- so that they had no idea how much time had elapsed since lunch nor whether it was 'time' for dinner. The subjects asked for dinner at about the same time regardless of whether or not they had a snack.
The study results raise questions about snacking's impact on weight gain. But dieticians contacted by WebMD had some problems with the study's methods. Jackie Berning, PhD, RD, an associate professor of nutrition at the University of Colorado in Colorado Springs, zeroed in on the study's finding of no big change in blood glucose levels in the men, despite their having consumed a snack. "Storage, to me, is the big question. ... The assumption I got [from the study] is that [snacking] tends to favor storage, which would tend to favor fat. But they don't know that. Maybe [the extra glucose] is going to the brain. Maybe [the subjects] were reading a hard book. Maybe it's going to the liver or muscles. If they're twitching their foot maybe it's going there."
A recent poster presented at the American Dietetic Association's annual meeting by researchers from the University of Memphis concluded that timing of food intake is unimportant when it comes to putting on weight. "Some say timing has an effect on fat storage and body weight. We found it does not," says Linda Clemens, EdD, RD, a professor at the school. Clemens questioned the "artificial environment" in which the study was conducted, as well as its small size, but calls the results interesting.
Wahida Karmelly, MSRD, an associate research scientist at Columbia University in New York, says that as a practicing dietician, she is less concerned with timing of food intake than amount. "Considering 50% of the adult population is overweight in this country, and obesity is rising in other parts of the world, we have to think of calories. People are losing sight of caloric intake," she says.
Karmelly says the study raises at least one important dietary issue: the concept of satiety -- a basic, but in some overeaters, elusive concept. Karmelly says she often asks clients to rate from zero to five how they feel hunger-wise before eating. "I have found people so often put in zero. They're not hungry. But it's time to eat." And so without thinking, that's just what they do.