Among common diet advice like “always eat breakfast” and “never eat after 8 p.m.” (do what you want, the timing doesn’t really matter), there’s the old stand-by, “when you think you’re hungry, drink something.” The idea is that it’s easy for your brain to mistake thirst signals for hunger, so you sometimes end up eating extra calories when you could have just chugged a glass of water. Is that really true? According to science, the answer is no.
In a 2008 study published in the Journal of the American Dietetic Association, Purdue University researchers had 128 people record both their feelings of hunger and thirst and everything they ate and drank for one week. They found no evidence that thirst led people to eat. Only feelings of hunger were associated with eating.
But what they did see is even more interesting. 62 percent of the time, people engaged in what the researchers called “inappropriate ingestive behaviors” — things like drinking without being thirsty, eating without being hungry, or not eating or drinking even though they were hungry or thirsty. In other words, more than half the time, people made dietary choices that had nothing to do with the signals their bodies were .
Why don’t people listen to their bodies? According to the researchers, it’s probably because food is so widely available and social snacking is so common that we’ve stopped considering eating and drinking as ways to relieve hunger and thirst. What’s more, our energy sources are all mixed up — some sodas have the same calorie content as a sandwich, and you can eat the same amount of white bread as wheat bread but feel much less satisfied.
So if we’re all that disconnected from our bodies’ signals, what should we do? Drinking plenty of water is still a sure bet, since it doesn’t contain calories and good hydration has all sorts of unexpected benefits. Changing the way you think about food can help, too. According to Harvard Medical School, eating mindfully — with slow, small bites, while appreciating the flavors and aromas — could lead you to eat less overall.