The belief that eating slowly will help you lose weight has been around for so long that it's taken as gospel without much consideration as to the science behind it. Dieters are advised to slow down, struggle through their scrambled egg whites, with chopsticks if necessary. But that truism that eating slowly is an integral slice of the weight-loss pie isn’t as simple as what a single study would have you believe.
Feeling like you’ve had a good meal is probably an important component of any weight-loss strategy.
A recent research study published by a group of Dutch scientists made national headlines by suggesting that eating slowly doesn't make you eat less than if you eat more quickly. The researchers compared what happens to meal size and appetite by having a group of volunteers eat a leisurely two-hour lunch, and at another time, eat the same lunch in just 30 minutes. They found that the volunteers did indeed feel fuller after the leisurely meal, and were still fuller several hours later. But despite this, when presented with a tempting array of junk food afterward, they ate just as many calories as they did following their 30-minute meal. In other words, eating more slowly left them feeling more sated, but that satiation didn't translate into abstention when the opportunity arose for a post-lunch snack.
What does this mean for those trying to lose weight? Is eating slowly really not worth your time? Much as I’m pleased to see another research study debunking my least favorite diet myth, what this experiment shows more than anything is how powerful our "food environment" is – especially when it’s left to its own devices to dominate our lives. But we don’t need to be helpless in the face of our food environments. Indeed, we can learn to manipulate them quite effectively.
First off, let’s take a closer look at the study that has everyone all worked up. Further scrutiny of the finding that there was “no difference” in junk food consumption after the fast and slow meals is misleading. There was actually a moderate difference – the participants ate 10 percent fewer calories after the slow meal. It’s just that this difference was deemed not statistically significant due to variability in the results. Then there's the issue of the experimental protocol: comparing a 30-minute meal to a 2-hour meal just isn’t realistic for how we eat today. When was the last time you spent two hours eating lunch? Even 30 minutes would be considered a leisurely lunch by many these days, so this study didn’t test a truly fast-eaten meal.
What’s more, another recent study done in the U.S. actually found the opposite result, reporting that eating slowly and chewing each bite 20-30 times did increase fullness and cause a 10 percent decrease in calorie intake. This decrease was statistically significant because the data in that study weren't as variable. But that study allowed unlimited water consumption with the meals, and the people who were eating slowly drank more, so it was impossible to work out whether the beneficial effect of slow eating was really a water effect in disguise.
The takeaway in this blizzard of data and conflicting conclusions is this: When it comes to nutrition studies, often we need to take the weight of evidence from multiple studies rather relying on the results from any individual study because the numbers are messy and are often influenced by how the study is designed and carried out.
So which is it? Is it worth spending an hour picking over a Caesar salad in the name of weight loss? My feeling is, if eating really slowly had a huge effect on calorie intake, it would have been proven by now, and it hasn’t been, so at best we are probably looking at a modest effect of slow eating on weight control. Second, while research on spreading out your meals to a heroic two hours might be inconclusive with regard to benefit, that is not to say that the opposite behavior—gobbling—is not harmful. When we dine as though we were competing at the annual Coney Island hot-dog eating contest, shoving in the next mouthful before we have fully swallowed the one before, what we miss out on is an appreciation of the flavor of each bite. This isn’t just about enjoying food for enjoyment’s sake —feeling like you’ve had a good meal is probably an important component of any weight-loss strategy that is sustainable in the long term. The top two reasons dieters offer for giving up on their quests to lose weight are “hunger” and “missing enjoyable food,” so anything that increases your enjoyment without increasing calories is a winning strategy.
Now an admission: Although I’m a nutrition scientist and weight-loss expert, I’m also a sometimes-gobbler. I’m busy, and as a result I rush, I multitask, and, yes, sometimes gobble. Yet I’ve been the same slim weight now for 17 years and counting. This fits with what I believe about sustainable weight control, which is that there is more than one way to make it work, and having an array of good strategies up our sleeve makes it easier than trying to rely on just one, especially when science can’t prove it works, anyway.
Dr Susan Roberts is a professor of Nutrition and professor of psychiatry at Tufts University, and author of The "I" Diet and The Instinct Diet. She welcomes comments on this article and her program through her website (www.instinctdiet.com).