Nuggets on Eating--How Much, When, and Why

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We heard some morsels worth repeating at a psychology department colloquium about food and eating last week on campus.

John de Castro of Georgia State University presented his research on the physiological, psychological and sociological influences on food and fluid intake in humans.

We didn't hear much about fluid, except for a brief mention of alcohol, but we did hear a couple of tidbits about food intake that surprised us and heard many kernels that confirmed our suspicions.

For instance, as we've always suspected, it's not our fault if we find ourselves starving at 10 at night because, as the day progresses, we need to eat more to feel satiated. Put another way, each calorie satisfies for a shorter time. Late nights with Conan and the new time slot for Bill Maher may take the blame for our increasingly hefty society.

Now consider this little surprise. People seem to experience an increase of appetite at the full moon. Don't get too excited. The effect is real but slight. De Castro speculated that the increased light at night keeps us up and eating, just as electric lights, Conan and Bill Maher do.

More good news for those of us who agonized over how much we ate as fall came around each year. It's normal and it's probably physiological--perhaps a vestige of the need to fatten up for food scarcity during the winter months. People's daily intake is 200 calories per day greater in fall than in the rest of the year.

Bad news here (but not a shock): Social eating is death for the diet.

Intake rises 44 percent when a meal is taken socially versus when a meal is taken alone. The size of the increase is probably affected by the increased duration of the time at the table because the rate of ingestion is no quicker in company. Furthermore, the bigger the dinner party, the more we'll eat. (Have you ever seen a fat hermit?)

The increase with company is true for all times of the day, all days of the week, all kinds of snacks and meals at all locations. Alcohol exaggerates the pattern (that's the fluid-intake finding, folks).

Here's a little surprise: Although women said that they eat less when they are with a man (think Scarlett O'Hara here, eating before the party so guests could admire her tiny appetite), the data belie their assertions. Women eat more when they are with a man, somewhat less when they are with another woman, and still less when they eat alone.

Lose your appetite at the office party? You're not alone. People eat more when they are with family and friends, but coworkers and mere acquaintances make them lose their appetite.

Here's the best news of all for guilty eaters and parents of tubbies. You're not to blame--maybe. Twin studies show that genes, not upbringing, are the main influence on intake. Genes determine how responsive people are to the hunger they feel.

The body's desire to keep its weight by making appetite adjustments was a less than impressive intake factor. If we eat a whole lot one day, we will probably not cut back the next day to compensate--unless we make a conscious decision and have the character to stick to it. Without the intervention of willpower, however, we may eat slightly less two to three days later. Then it's back to normal. "Only when homeostasis is way out of whack do you get an alteration in intake," de Castro said.

For all you skeptics, most of de Castro's findings are based on studies of 700 subjects. Perhaps it's tough to swallow, but chances are the findings apply to you, too.

Originally published on February 4, 1997