In the first nationwide study of its kind anywhere, Department of Human Nutrition researchers analysed the relationship between self-reported speed of eating and body mass index (BMI) in more than 1500 New Zealand women aged between 40 and 50. Women in this age bracket are known to be at high risk of weight gain.
Study principal investigator Dr Caroline Horwath says that after adjusting for other factors including age, ethnicity, smoking, physical activity and menopause status, the researchers found that the faster women reported their eating speed to be, the higher their BMI.
“For every one-step increase in a five-step scale ranging from ‘very slow” eating to “very fast”, the women’s BMI increased by 2.8 %, which is equivalent to a 1.95 kg weight increase in a woman of average BMI for this group.”
Dr Horwath says that because the current study is unable by itself to show whether faster eating speed actually causes increased BMI, the researchers have been following up the women to see if faster eaters gain more weight over time.
“The size of the association found in this initial research suggests that if there is a causal link, reduction in eating speed is a very promising way to prevent weight gain and may lead to decreases in BMI similar or greater than those sustained in weight management programmes.”
Results from the 2-year follow-up are expected to be published next year. If analysis of the data confirms a causal relationship, Dr Horwath and her team will test interventions that include a focus on encouraging women to eat more slowly.
“If such interventions prove effective, they could be used alongside other non-dieting approaches we have previously trialled with overweight or obese women. These approaches successfully prevented weight gain in at-risk women and even produced significant weight loss in some. Our interventions included intensive training in relaxation techniques and how to recognise and avoid stress-related triggers for eating.”
Such non-dieting approaches are gaining increasing interest from dietitians, as the traditional dieting approach of restricting both calories and foods types has shown poor results in achieving long-term weight loss, she says.
“Studies have found that many dieters regain any weight they lose within five years and often end up heavier than when they began.”
The eating speed and BMI study is published in the latest issue of the Journal of the American Dietetic Association.
For more information, contact
Dr Caroline Horwath
Department of Human Nutrition
University of Otago
Tel 64 3 479 7946