Short Oral Presentation Nutrition Society of Australia 50th Annual Scientific Meeting 2026

Timing matters: associations between women's chronotype, their body composition and dietary time-periods (145937)

Rozanne Kruger 1 2 , Carlien van der Merwe 2 3 , Marilize Richter-Cottle 2 , Bernhard H Breier 2 , Jeroen Douwes 4 , Mirjam M Münch 4 5
  1. School of Allied Health, Sport and Social Work, Griffith University, Gold Coast, Qld, Australia
  2. School of Sport, Exercise and Nutrition, Massey University, Auckland, 0745, New Zealand
  3. Centre of Excellence for Nutrition, North West University, Potchefstroom, 2531, South Africa
  4. Centre for Public Health Research, Massey University, Wellington, 6140, New Zealand
  5. Centre for Chronobiology, Research Cluster Molecular and Cognitive Neurosciences, Department of Biomedicine, University of Basel, Basel, 4031, Switzerland

The circadian timing system is influenced by chronotype as well as other important time cues, including meal timing and composition (1). The aim of this study was to investigate if the body composition of healthy New Zealand (NZ) women with different chronotypes is associated with meal timing linked with dietary intake across the day. Pre-menopausal, non-pregnant, Pacific and European NZ women (n = 287), aged 18 - 45 (median; 25 - 75th percentile 27; 22 - 35) were included in the study (2). DXA scans determined whole body fat- (BF%), android- and gynoid fat percentages. Body mass index (BMI) was calculated. Chronotype was determined using the Munich Chronotype Questionnaire (3). Dietary intake (energy and nutrients) and mealtimes were assessed using five-day estimated food records. Fasting venous blood samples were collected to assess lipid profile, glucose and hormonal control. Overall (24h) energy distribution was assessed using hourly food intakes, then grouped into dietary time-periods. Two-way repeated measures ANCOVA was conducted to compare the effect of chronotype on the distribution of mean energy and macronutrient intakes across dietary time-periods. Differences between chronotypes were assessed by multiple linear regression models within body composition groups, adjusted for age, deprivation index and ethnicity. A third (n = 97) of the women were classified as evening types (ET), 35 as morning types (MT), and 155 as intermediate chronotypes (IT). The ET vs. MT respectively had higher BMI (31.4 vs. 24.2 kg/m2), BF% (36 ± 7% vs. 32 ± 9%), android-to-gynoid fat (AG) ratio (0.98 (0.81, 1.06) vs. 0.80 (0.69, 0.96)), and workday-sleep duration (9.13 ± 2.22 vs. 8.16 ± 1.06), all p < 0.05. Overall energy intakes were not different between MT, IT and ET, but slightly higher in ET (8745 ± 2577 kJ) vs. MT-IT combined (8532 ± 1992 kJ; p = 0.03). The MT-IT had lower energy and macronutrient intakes in the evening after 20:00 (p < 0.05) than the ET who instead had lower intakes in the morning before 10:00. The ET classified within the high BF% and high AG ratio groups had high probability of lower intakes of energy and macronutrients (excluding fat for AG) in the morning (before 10:00), and higher energy and macronutrient intakes (excluding protein for BF%) in the evening (after 20:00). Compared with ET, the MT-IT had better lipid and glucose biomarkers (all p < 0.05). Among women, ET consumed less nutrient-dense, more energy-dense food alongside higher evening vs. morning dietary intakes, which is opposite to MT-IT. The higher energy and macronutrient intakes at night-time among ET was significantly associated with higher BF%, AG ratio and poorer metabolic health, confirming previous research (4), which suggests ET may be more prone to higher central body fat and developing obesity.

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  2. Kindleysides S, Kruger R, Douwes J et al. (2019) JMIR Res Protoc 8(8):e14529.
  3. Roenneberg T, Wirz-Justice A & Merrow M. (2003) J Biol Rhythms 18(1):80-90.
  4. Alum EU. (2025) J Health Popul J Nutr 44(1):367.