Interindividual, intraindividual and intermeal variance in energy and macronutrient intake: a multilevel analysis

Background:

Our aim was to reveal whether interindividual, intraindividual or intermeal variance is a potential source of unexplained variability in energy and macronutrient intake.

Methods:

Diet was assessed via three 24h recalls in an EPIC-Potsdam substudy. Energy and nutrient intake of single intake events were summarized in 4 episodes: morning, noon, afternoon and evening. Multilevel analysis was conducted with intake of individuals, of 24h recalls and during intake episodes as random effects and subject-specific factors as well as parameters describing recall days as fixed effects. Intraclass correlation coefficients (ICC) were calculated to study which intake level and which intake episode contributed most to variance in energy and nutrient intakes.

Results:

Recall days did not explain any variance in energy or nutrient intake. 8.8% of the variability in energy intake was accounted for by subjects leaving 91.2% of the variability within intake episodes. The results were similar for carbohydrate and fat intake where the subject level explained 9.6% and 8.9% and intake episodes 90.4% and 91.1% of the variance, respectively. For proteins, 2.7% of variance was explained by subjects and 97.3% by intake episodes. Regarding intake episodes, the highest ICCs for energy and nutrients (0.50 to 0.62) were seen in the morning. The lowest ICCs were shown in the afternoon for energy (0.19) and protein (0.12) intake and at noon for carbohydrates (0.17). ICCs for fat were similarly low at noon and in the afternoon (0.18 and 0.17).

Conclusion:

The findings suggest that intraindividual variance played a minor role in energy and nutrient intake variability while intermeal variance had an essential impact. The morning was most stable regarding energy and nutrient intake while stability was lowest during noon for carbohydrate and during afternoon for energy and protein intake. Further research is needed to elucidate the relevance of these findings for human health.