February 12, 2018

expert reaction to study looking at eating speed and obesity

Scientists investigate the association between effects of eating speed on obesity in patients with diabetes, in a new study, published in BMJ Open.

Prof. Susan Jebb, Professor of Diet and Population Health, University of Oxford, said:

“This large observational study of nearly 60,000 men and women with type 2 diabetes studied over a 6 year period adds to previous research in Japan suggesting a link between a faster eating rate and increased risk of obesity.  Moreover it shows that reductions in the rate of eating over time are associated with a reduction in weight.

“Although this is only an observational study and the association cannot be assumed to be causal, there is a plausible mechanism.  Laboratory studies, which have experimentally manipulated eating rate, consistently show that a slower eating rate leads to a reduced energy intake at the meal¹.  However the outstanding challenge is to identify strategies to support people to eat more slowly in everyday life.  One study has suggested that changing the form and texture of food can slow eating rate², while other research is focused on training individuals to eat more slowly³, but neither have been tested at scale.  For now, while there is little evidence that simple advice to eat more slowly is effective in reducing eating rate it is unlikely to be harmful  for people who are overweight and it may encourage a more reflective eating style and reduce the risk of overconsumption.”

1 Robinson, Almiron-Roig, Rutters et al. AJCN 2014; 100(1):123-151

2 Ford, Bergh, Sodersten et al. BMJ 2010; 340:b5388

3 Bolhuis, Forde, Cheng et al. PLoS One 2014; 9:e93370

Ms Catherine Collins, Registered Dietitian, said:

“Type 2 diabetes is increasing in the UK, and we know that obesity is an independent risk factor in developing this disabling condition – so any change in eating habits that can help moderate our calorie intake and lessen weight gain would be useful – healthwise – for most of us to adopt.

“So this study of over 60,000 Japanese adults with diabetes reviewed over a 6 year period evaluated the speed of eating and snacking habits with body weight.  It compared eating habits between three groups, termed on the basis of how fast they ate food – ‘fast’, ‘normal’ or ‘slow’ – and looked at other eating habits to see if they linked with body weight.

“What was clear from the study that those who ate slowly (however that was defined) were half as likely to be obese than those who ate their meals fast – and also likely to have a smaller waist circumference.  An increased waist circumference is linked to the body’s resistance to insulin, which in turn leads to an increased blood sugar and worsened blood sugar control.

“Less than 22% of those who ate ‘slowly’ were defined as obese, whereas 45% of those who ate ‘fast’ were obese.  (Note that BMI ranges in Japan are different – an ideal BMI is between 18.5-22.9, overweight BMI 23.0-24.9, and obese over 25¹).

“Do fast eaters become fat eaters?  Possibly – especially if we eat ‘mindlessly’, which has been shown to increase overall calorie intake.  Culturally, though, Japanese do not indulge in snacks as regularly as we do in the UK, so the findings are culture-specific and not necessarily applicable to us.  And unfortunately for a study on eating speed, the researchers didn’t qualify what made a fast eater, which is a major oversight.  Nor did they evaluate other factors linked to body weight and blood sugar control, such as exercise and shiftwork.”

1 www.ncbi.nlm.nih.gov/pubmed/14557832

Dr Simon Cork, Research Fellow in the Division of Diabetes, Endocrinology and Metabolism, Imperial College London, said:

“This is an interesting study, and confirms what we already believe, that eating slowly is associated with less weight gain than eating quickly.  This is likely due to the signals that originate in the gut communicating to the brain that you’re full in time to reduce the amount being eaten.  The quicker you eat, the less time the signals have to get to your brain.

“I would be slightly concerned about the scoring criteria that the authors have used to assess eating speed.  Simply asking the participants whether they eat ‘slow, fast, or normal’ is considerably subjective, and will no doubt skew any data based on how quick or slow participants perceive their eating speeds to be.

“Nevertheless, it is understood that eating speed has an effect (albeit likely a moderate one) on body weight.”

Dr Katarina Kos, obesity researcher and consultant in diabetes and weight management at the University of Exeter Medical School, said:

“The Japanese study cohort had a smaller proportion of women (about 30%) whilst in the UK obesity affects a higher proportion women.  It relies on self-reported eating speeds which has its limitations in terms of accuracy.

“It is not clear why people changed the perceived eating speed in the course of follow up of the six year study, and this would be of interest.  Whilst diabetes medication is taken into account, it would have also been important to consider physical activity which the authors explain, but most important is also blood sugar/diabetes control.  Poor control of diabetes can lead to weight loss amongst others, by loss of fluid.

“Whilst this epidemiological study looks at important and modifiable lifestyle changes, these observations must be verified in a non-diabetic cohort in our society and cultural and socioeconomic associations considered.  For now physicians working in diabetes and weight management like myself continue to recommend slower eating speed by which to limit portion size.”

* ‘Effects of changes in eating speed on obesity in patients with diabetes: a secondary analysis of longitudinal health check-up data’ by Yumi Hurst and Haruhisa Fukuda et al. published in BMJ Open on Monday 12 February 2018.

Declared interests

Dr Simon Cork: “No conflicts of interest.”

None others received.