By Janet Raloff

Web edition: February 18, 2009

Increasingly, we have become a nation of mindless eaters. Some federal scientists have been watching us, and particularly where we eat. Their observations, described in a report issued last week, suggest that a substantial share of calorie consumption occurs as a “secondary” activity. Like snacking, or dining when our mind is focused on something else — usually watching TV or driving.

One tip to avoid overeating: Pay attention to what you consume. Listen to the body. When it’s hungry, eat slowly (because satiety cues take a while to develop and register). And when the body says it’s had enough, accept that. Put down the fork. Drop the cookie you were about to bite. Pitch out what remains in your beverage glass or soft-drink can.

In other words, don’t eat when your attention is riveted elsewhere. Those of us who do run a high risk of obesity. The extra mindless intake that comes from distracted eating has been painstakingly quantified again and again by a research team at Cornell University headed by Brian Wansink.

So, how much do we eat mindlessly? The Agriculture Department researchers didn’t measure it in terms of calories but as time. And in 2007, the most recent year for which data are available, the nearly 13,000 surveyed men and women (15 and older) spent a little over an hour each day eating and drinking purposefully. By that I mean that at the time, this consumption was their primary activity. Perhaps a diner conversed with someone across the table. Maybe he ate at his desk while reading the newspaper. But on such occasions, people put food first.

We generally snack or otherwise engage in mindless eating almost another half-hour (26 minutes) each day — and spend twice that long downing snack drinks. This distracted consumption might take place while we’re driving to work, checking e-mails, watching our kids at a swim meet, or sitting in front of the television.

Some 4.5 percent of people report eating no real meals. They eat, of course, but in a grazing fashion at periodic intervals. Overall, the total time they spend eating is roughly comparable to those who do sit down to real meals.

But perhaps the most distressing finding about our nation, already in the throes of an obesity epidemic, is how many of us are “constant grazers.” Such diners spend at least 4.5 hours a day — but on average 8.2 hours — eating or drinking. As one might expect, the majority of time these people are snacking.

This group constitutes 11 percent of the population. Overall, roughly 10 percent of this group report eating “all day”. A third claim to drink all day.

I fall into the second category of constant grazers. There’s almost always a tea cup within reach. And as soon as it empties, I go to the kitchen (at home and at work) and brew another. I down unsweetened tea, so there shouldn’t be a calorie penalty associated with my caffeine addiction. But I suspect there are plenty of people who don’t eschew the sweeteners.

There was a time a little while back, oh maybe 2,000 to 6,000 years ago, when food was nearly universally hard to come by. It was an era known as the Age of Feast or Famine.

People were perpetually hungry. Except when they happened onto a big cache of berries, nuts, or perhaps some sizable animal. Then they gorged — only to enter another days-to-weeks-long period of mild to serious hunger.

With the advent of farming — and more recently, commercial food production — much of our planet has put that near-ubiquitous starvation behind us and entered the Age of Perpetually Bountiful Calories. We now have a hard time waiting to become hungry. Too many of us succumb instead to the visual or olfactory siren calls of food that bombard us from every angle, often at several-minute intervals.

We’d all be better off if we restricted eating until we could think about what we’re putting into our mouths and how much of it we really need. And snacking should be forbidden immediately before a meal. Then again, this being America the Plentiful, most people would view such delayed gratification as a nightmare. Oh well . . .