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expert reaction to study looking at nuts, weight and obesity

Research, published in BMJ Nutrition, Prevention & Health, reports a link between increased consumption of nuts and lower weight gain and obesity risk.


Dr Stephen Burgess, Group Leader at the MRC Biostatistics Unit, University of Cambridge:

“This is an observational study – it tells us about differences between people who choose to eat nuts compared with those who choose not to eat nuts.  It does not tell us what would happen if those who currently do not eat nuts instead decided to eat nuts.  That would require performing a randomized trial and intervening on people’s diet directly, which is not practical to do when investigating long term changes in health.

“There are many limitations to the study, several of which are noted by the investigators.  Nut consumption was measured once every four years by a questionnaire.  The questionnaire responses were self-reported by study participants, rather than being measured directly or validated by investigators.  Many other important factors that may explain differences in obesity levels between nut-consumers and non-consumers were either not measured, or were measured by questionnaire or at a clinic visit every four years.  The measure of nut consumption included peanut butter – most of the suggested benefits of nut consumption are not relevant for consumption of peanut butter.  Investigators did not consider ways that nut-consumers and non-consumers may have differed at entry into the study.

“While these findings are interesting, there are many other factors that may explain differences in weight gain between nut-consumers and non-consumers, including differences in lifestyle choices, and social and economic factors that influence health.”


‘Changes in nut consumption influence long-term weight change in US men and women’ by Xiaoran Liu et al. was published in BMJ Nutrition, Prevention & Health at 23:30 UK time on Monday 23 September 2019. 

DOI: 10.1136/bmjnph-2019-000034


Declared interests

Dr Stephen Burgess: “No conflict of interest to report.”


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