Why Eating Slowly Can Help You Cut Calories

By: Matthew Denos, PhD
Category: Matthew Denos, PhD

We all know that being overweight is a risk factor for a number of different diseases, including cancer, cardiovascular disease, and diabetes—yet the world has continued to see increasing rates of overweight and obesity in recent years. The latest scientific research suggests that a common but often overlooked piece of conventional dieting advice may help combat this worldwide weight epidemic: eating slower means eating less. Long supported by anecdotal evidence, the motherly admonition not to wolf down your food appears to have a real physiological basis and can actually help you cut calories.

Science now knows more about appetite control than ever before, including the fact that consumption of food is followed by hormonal changes in the body. In particular, the period of time directly following a meal is associated with a decrease in ghrelin—a gut peptide that has a powerful appetite-stimulating (orexigenic) effect—and increases in appetite-decreasing (anorexigenic) peptides like peptide YY (PYY) and glucagon-like peptide (GLP-1). All of these hormones act on the hypothalamus, playing important roles in the regulation of hunger, satiety (fullness), and energy intake.

Eating Slowly Stimulates Satiety Hormones

A recent study, conducted by Kokkinos et al. and published in a 2010 issue of the Journal of Clinical Endocrinology and Metabolism, tested the hypothesis that eating more slowly would be associated with increased satiety, as well as higher anorexigenic peptides (like PPY and GLP-1) and lower orexigenic peptides (like ghrelin). To do this, the researchers recruited study participants and provided them with ice cream in exchange for blood samples taken before, during, and after they ate it.

The 17 male volunteers who participated in the study all consumed the same test meal consisting of 300 ml of ice cream, but they ate the ice cream at different predetermined rates. While some participants ate the ice cream in two equal portions consumed 5 minutes apart, others ate it in seven equal portions over 30 minutes (one portion eaten every 5 minutes). Study sessions were 210 minutes long for all participants, and blood samples were taken before the meal and at 30-minute intervals throughout the session in order to measure glucose, insulin, plasma lipids, ghrelin, PYY, and GLP-1.

When the blood samples were analyzed, the results showed that the amounts of PYY and GLP-1 were greater after the 30-minute meal than after the 5-minute meal, suggesting that eating at a more moderate pace induces a stronger response of anorexigenic gut peptides—the hormones that suppress appetite. There was no significant difference found in ghrelin values between the 30-minute and 5-minute meals, although ghrelin levels tended to be lower at the 2-hour time point after the 30-minute meal. This is the first study to show a potential physiological explanation for the tendency to consume less when eating at a moderate rate—an increased PYY and GLP-1 response, which induces feelings of satiety.

Eating Fast is Associated With Overweight

This recent study built on the findings of two earlier research studies. A study by Maruyama et al of Osaka, Japan, published in a 2002 edition of the British Medical Journal, looked at whether eating quickly was associated with being overweight. Their examination of questionnaires from over 4000 adults found that those who ate quickly had the highest values for weight, body mass index, and total energy intake. Eating quickly increased the odds of being overweight for both men and women. Moreover, both eating quickly and eating until full were found to have a significant association with being overweight, suggesting that the effect of the combination of those two eating behaviors on weight may be significant.

Eating Rate Determines Level of Satiety And Pleasantness After A Meal

In 2008, Andrade et al. published the results of their study on the impact of eating rate on development of satiation and energy intake in the Journal of the American Dietetic Association. Thirty healthy women, recruited from the University of Rhode Island, took part in the study. The participants were given generous portions of lunch and water and told to eat as much as they wanted, until they were comfortably full (satiated). In the quick-eating condition, participants were provided with a large soup spoon and instructed to eat as quickly as comfortably possible, with no pauses between bites. In the slow-eating condition, participants were provided with a smaller teaspoon and told to eat small bites, putting the spoon down between each bite and chewing 20 to 30 times.

When the two conditions were compared, it was found that participants consumed significantly less food during the slow condition than in the quick condition, both in terms of energy intake and weight of food, and consumed more water. Even though the quick eaters had a greater energy intake, slow eaters expressed significantly higher satiety ratings after the meal and had lower hunger ratings. Participants also found the slow-eating condition more pleasant than the quick condition. These results are also consistent with the hypothesis that it takes at least 20 minutes after ingesting food for physiological feedback to take place, no matter how much food is eaten.

There are several possible explanations for the results of this study. One is that taking a longer time to eat allows for physical feelings of satiety to set in, signaling that the body is full before too much energy has been consumed. Another possibility is that the techniques used to slow down the womens eating rate helped them to eat less and feel fuller—for example, extensive chewing of each bite may stimulate feelings of satiety. The increased amount of water consumed when eating slowly may also have made the women feel fuller. Finally, eating at a slower pace was rated as more pleasant by the women, supporting the idea that eating at a leisurely pace allows one to savor all aspects of the food, from its appearance and smell to its taste and feel in the mouth, thereby resulting in greater satisfaction from fewer calories.

The results of these three scientific studies offer evidence that eating at a slower pace will naturally result in greater feelings of fullness and less overall caloric intake, while gulping down food may increase the risk for being overweight. One even offers several practical suggestions for taking in less energy and increasing satiation: take smaller bites, chew thoroughly, and put the utensil down between bites. It certainly cant hurt to slow down and savor your food, and it just might help you lose weight.

Matthew Denos is a scientist and passionate advocate of healthy eating who closely follows current research on diet and weight loss. Please visit www.weightlosstriumph.com to learn more.