Researchers studying food behavior have discovered that eating too quickly may be an important contributor to becoming overweight.
Eating quickly previously has been linked to a higher body mass index, according to Prof. Hiroyasu Iso of Osaka University, Japan, and colleagues in an article on the British Medical Journal website.
The team investigated these factors among 3,287 Japanese men and womenaged 30 to 69 years. About 33 percent of the men and 22 percent of the women were overweight (body mass index of 25 or higher). The participants were given questionnaires to record their dietary habits, including “eating until full” and speed of eating.
Over half of women (58 percent) and men (51 percent) said that they ate until full. In the study, this refers to eating a “large quantity of food in one meal.” The participants’ self-reported speed of eating was backed up by reports from a friend. Just under half of men (46 percent) and just over a third (36 percent) of women reported eating quickly. For both sexes, eating until full and eating quickly were positively associated with weight, body mass index and total energy intake.
The researchers estimate that the combination of eating quickly and eating until full more than triples the risk of being overweight. This calculation took into account age, alcohol intake, smoking, occupation and regular exercise.
They conclude: “The combination of the two eating behaviors has a substantial and additive effect on being overweight. Obesity or being overweight is an important risk factor for lifestyle related diseases such as cancer, cardiovascular diseases, and diabetes.”
The experts point out that previous studies show “essentially the same trends,” that is, associations between the speed of eating and body mass index, weight gain and total energy intake. But they call for more research to verify a causal link.
Commenting on the study in an editorial, Dr Elizabeth Denney-Wilson of the University of New South Wales, Australia, and Karen Campbell from Deakin University in Australia say that this study adds to the evidence that eating behaviors are central to promoting a positive energy balance (taking in more energy than is used) and may contribute to the current epidemic of obesity.
“The drive to overconsume energy when it is available is probably an evolutionary imperative; however, until the last decade or so most adults did not have the opportunity to take in enough energy to enable fat to be stored,” the authors write. “With the increased availability of inexpensive food in larger portions, fast food, and fewer families eating together and eating while distracted (e.g. while watching TV), eating behaviors are changing, and this may be contributing to the obesity epidemic.”
It’s still unclear exactly what drives us to eat quickly or to eat until we are full, and whether these drivers are modifiable, they add, but our present environment makes it difficult to regulate our energy intake. It has been found in experiments that we are relatively bad at regulating energy intake, relying on visual signals more than our internal feelings of fullness. We usually do not eat less of a food that had been altered to contain more energy — we tend to eat more when faced with a wider variety of foods, and we eat more when bigger portions are served.
Upbringing also plays a role. “It seems likely that any early capacity for energy regulation may be over-ridden by parental pressure to eat more,” the authors suggest. Research indicates that the majority (85 percent) of parents may encourage children to eat more than they would choose to.
A study of preschool children found that the strongest predictor of amount consumed at a meal was the amount served, regardless of earlier snacks, so the experts urge caregivers to adopt “a child-led feeding strategy that acknowledges a child’s desire to stop eating.”
They would also like to see physicians working with parents to encourage healthy eating habits in their children such as eating slowly, serving appropriate portion sizes, and eating as a family in a non-distracting environment. “Given the fundamental importance of preventing overweight, clinicians need to engage with parents,” they write. “Evidence shows that parents can be supported to make effective changes to their children’s eating habits.”
The authors conclude that eating together with an adult who can provide “role modeling with slow and relaxed eating” is likely to be useful in teaching children to listen to their body’s own signals.