Why eating quickly could accelerate weight gain

New research suggests when people eat quickly there's less time for the "I'm full" signal to reach the brain, increasing the risk of overeating.

Japanese researchers suggest slowing the pace can help the brain recognize when the stomach is full

Eating speed may have an impact on a person's weight, a new study suggests. (Yoshikazu Tsuno/AFP/Getty)

If you're trying to lose weight, simply slowing down when you eat might make a difference.

That's the suggestion from researchers in Japan, who studied possible links between eating habits and weight loss among nearly 60,000 people diagnosed with Type 2 diabetes.

Leah Cahill, an assistant professor at Dalhousie University in Halifax who researches eating but was not involved in the study, says the results are empowering.

"What stands out to me about this study is the positive thought that eating speed is a modifiable risk factor in a world where people feel many health risk factors are beyond their control," she said in an email.

'I'm full' signal

Some experts believe when people eat faster there's less time for the "I'm full" signal to reach the brain, increasing the risk of overeating.

Study authors Haruhisa Fukuda and Yumi Hurst of Kyushu University Graduate School of Medical Sciences in Fukuoka, Japan, present a similar hypothesis in BMJ Open, which published their research this week.

The study's statistical analysis also found cutting down on snacks after dinner and not eating within two hours of bedtime were linked to weight loss; skipping breakfast was not.

The study participants were asked about their dietary and sleep habits, as well as alcohol and tobacco consumption. At regular checkups over six years, clinicians measured their weight and waist circumference and tested their blood, urine and liver function.

The participants were asked whether they eat "slow, fast, or normal," which the researchers didn't define. The subjectivity of the answers is one of the study's limitations.

​Compared with those who said they eat quickly, those who eat at a normal speed were 29 per cent less likely to meet the Japanese definition of obese. Those who said they eat slowly fared even better.

Obesity is associated with a higher risk of developing diabetes, cardiovascular disease and some forms of cancer.

What's missing

The research is considered an observational study, which means it cannot provide conclusions about cause and effect.

It should also be noted the researchers didn't look at energy intake or physical activity levels, which could affect the results.

A Japanese study released in 2014 that tracked the eating habits of girls over a three-year period also found evidence of a possible connection between eating speeds and weight gain or loss.

With files from CBC's Amina Zafar