Individual Postprandial Glycemic Responses to Diet in n-of-1 Trials: Westlake N-of-1 Trials for Macronutrient Intake (WE-MACNUTR)

J Nutr. 2021 Oct 1;151(10):3158-3167. doi: 10.1093/jn/nxab227.


Background: The role of different types and quantities of macronutrients on human health has been controversial, and the individual response to dietary macronutrient intake needs more investigation.

Objectives: We aimed to use an 'n-of-1' study design to investigate the individual variability in postprandial glycemic response when eating diets with different macronutrient distributions among apparently healthy adults.

Methods: Thirty apparently healthy young Chinese adults (women, 68%) aged between 22 and 34 y, with BMI between 17.2 and 31.9 kg/m2, were provided with high-fat, low-carbohydrate (HF-LC, 60-70% fat, 15-25% carbohydrate, 15% protein, of total energy) and low-fat, high-carbohydrate (LF-HC, 10-20% fat, 65-75% carbohydrate, 15% protein) diets, for 6 d wearing continuous glucose monitoring systems, respectively, in a randomized sequence, interspersed by a 6-d wash-out period. Three cycles were conducted. The primary outcomes were the differences of maximum postprandial glucose (MPG), mean amplitude of glycemic excursions (MAGE), and AUC24 between intervention periods of LF-HC and HF-LC diets. A Bayesian model was used to predict responders with the posterior probability of any 1 of the 3 outcomes reaching a clinically meaningful difference.

Results: Twenty-eight participants were included in the analysis. Posterior probability of reaching a clinically meaningful difference of MPG (0.167 mmol/L), MAGE (0.072 mmol/L), and AUC24 (13.889 mmol/L·h) between LF-HC and HF-LC diets varied among participants, and those with posterior probability >80% were identified as high-carbohydrate responders (n = 9) or high-fat responders (n = 6). Analyses of the Bayesian-aggregated n-of-1 trials among all participants showed a relatively low posterior probability of reaching a clinically meaningful difference of the 3 outcomes between LF-HC and HF-LC diets.

Conclusions: N-of-1 trials are feasible to characterize personal response to dietary intervention in young Chinese adults.

Keywords: diet pattern; macronutrient; n-of-1 trial; nutrition; postprandial glycemic response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bayes Theorem
  • Blood Glucose Self-Monitoring*
  • Blood Glucose*
  • Diet, Fat-Restricted
  • Dietary Carbohydrates
  • Dietary Fats
  • Eating
  • Female
  • Humans
  • Postprandial Period
  • Young Adult


  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats