Walnut consumption increases activation of the insula to highly desirable food cues: A randomized, double-blind, placebo-controlled, cross-over fMRI study

Diabetes Obes Metab. 2018 Jan;20(1):173-177. doi: 10.1111/dom.13060. Epub 2017 Aug 17.


Aims: The use of walnuts is recommended for obesity and type 2 diabetes, although the mechanisms through which walnuts may improve appetite control and/or glycaemic control remain largely unknown.

Materials and methods: To determine whether short-term walnut consumption could alter the neural control of appetite using functional magnetic resonance imaging, we performed a randomized, placebo-controlled, double-blind, cross-over trial of 10 patients who received, while living in the controlled environment of a clinical research center, either walnuts or placebo (using a validated smoothie delivery system) for 5 days each, separated by a wash-out period of 1 month.

Results: Walnut consumption decreased feelings of hunger and appetite, assessed using visual analog scales, and increased activation of the right insula to highly desirable food cues.

Conclusions: These findings suggest that walnut consumption may increase salience and cognitive control processing of highly desirable food cues, leading to the beneficial metabolic effects observed.

Trial registration: ClinicalTrials.gov NCT02673281.

Keywords: appetite control; obesity therapy; randomised trial; type 2 diabetes.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Appetite Regulation*
  • Body Mass Index
  • Boston / epidemiology
  • Breakfast
  • Cerebral Cortex / diagnostic imaging
  • Cerebral Cortex / metabolism*
  • Cross-Over Studies
  • Cues
  • Diabetes Mellitus, Type 2 / epidemiology
  • Diabetes Mellitus, Type 2 / etiology
  • Diabetes Mellitus, Type 2 / prevention & control
  • Double-Blind Method
  • Female
  • Food Preferences
  • Functional Food*
  • Humans
  • Juglans*
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neurons / metabolism*
  • Nuts*
  • Obesity / diagnostic imaging
  • Obesity / diet therapy*
  • Obesity / metabolism
  • Obesity / physiopathology
  • Risk
  • Satiety Response

Associated data

  • ClinicalTrials.gov/NCT02673281