There’s a study going around that claims eating slowly could help you lose weight — or so it seems. The study, released by a group of researchers in Japan, analyzed data from 59,717 diabetic patients during visits to primary care doctors. The participants were weighed, measured, and asked about certain eating habits: their use of medication, the times of night they ate dinner, whether they snacked after dinner, whether they skipped breakfast, and how often they drank alcohol. They were also queried on their sleeping and smoking habits.
Of all these factors, just three were found to yield statistically significant results. Drinking infrequently, avoiding eating before bed, and eating more slowly were correlated with reductions in BMI.
“Slow and steady slims the waist,” a New York Post article boldly asserted.
“3 Simple Habits Linked to Weight Loss,” a particularly enthusiastic headline from CBS claimed.
However, these statements gloss over a lot of relevant information about the actual study and the data collected — like, for instance, the fact that all of the study’s participants were patients with diabetes. Should we really generalize these results to the population as a whole?
We took a closer look and found a few other reasons to be skeptical.
First of all, the survey was based on participants’ self-reported impressions of their eating speed, and there were no parameters given to quantify these categories. So two participants could walk into the doctor’s office typically eating at the exact same speed and yet give two different answers. This means that no matter how carefully researchers controlled other variables, a subjective factor is at play.
As for the numbers, the overwhelming majority of study participants either claimed they ate quickly or at a normal speed. In total, 22,070 participants claimed to be fast eaters, 33,455 claimed to eat at a normal speed, and only 4,192 admitted to eating slowly. Of those thousands of self-described fast eaters, only 171 claimed to have become slow eaters by the end of the study.
The results claim to have observed the relationship between changes in BMI over time and the speed of eating, but how the researchers chose to track these changes leaves room for significant uncertainty.
For instance, the average number of health check-ups completed by participants in the study was 1.9. A whopping 30 percent of those counted only reported their eating speed one time over the course of the study. Would that not make measuring changes in BMI kind of difficult? Meanwhile, for those participants who reported more than one eating speed between the first and final visit, results were pared down in a way that prioritized slower eating speeds.
It’s risky to draw sweeping conclusions from such imprecise data. The results also indicate that a reduction in the frequency of alcohol consumption showed an increased likelihood of obesity. Does that mean that we should all drink more alcohol to lose weight?
We’re not saying that there aren’t merits to eating slowly. In fact, eating too quickly could cause other problems that have nothing to do with body size. Eating too quickly could negatively affect nutrient absorption and the ability to digest food without discomfort. Eating mindfully, and therefore more slowly, has also been shown to help diabetes patients manage their blood sugar. This effect of mindful eating could also have something to do with the results of this study for diabetics.
So don’t go gobbling down your food just because this study might not prove cause and effect — we’re simply saying that there’s reason to take studies like this with a grain of salt. And sitting at the dinner table with a timer set between bites might not bring you the weight loss you want.