title: Evaluating energy intake measurement in free-living subjects: when to record and for how long?
abstract: OBJECTIVE
  To nutritionally analyse mean energy intake (EI) from different 3 d intervals within a 7 d recording period and to evaluate the seasonal effect on energy and nutrient intake.
  
  
  METHODS
  Cross-sectional study of dietary intake collected with 7 d food diaries.
  
  
  METHODS
  Aberdeen, north-east Scotland, UK, between 2002 and 2004.
  
  
  METHODS
  Participants from two long-term trials were pooled. These trials, investigating genetic and environmental influences on body weight, were the Genotyping And Phenotyping (GAP) study and a cohort observational study, Rowett Assessment of Childhood Appetite and metaboLism (RASCAL). There were 260 Caucasian adults, BMI range 16.7-49.3 kg/m2, age range 21-64 years.
  
  
  RESULTS
  Mean EI for Wednesday, Friday and Saturday had the closest approximation to the 7 d mean (0.1 % overestimate). A gender x season interaction (P = 0.019) with a different intake pattern for females and males was observed. For females, lower mean (se) EI was recorded in summer (8117 (610) kJ) and autumn (7941 (699) kJ) compared with spring (8929 (979) kJ) and winter (8132 (1041) kJ). For males, higher mean (se) EI was recorded in summer (10 420 (736) kJ) and autumn (10 490 (1041) kJ) compared with spring (9319 (1441) kJ) and winter (9103 (1505) kJ).
  
  
  CONCLUSIONS
  The study results indicate that 3 d weighed intakes recorded from Wednesday, Friday and Saturday are most representative of 7 d habitual intake in free-living subjects. They also indicate that seasonality has a limited effect on EI and no effect on macronutrient intake.
authors.affiliation: Division of Obesity and Metabolic Health, Rowett Institute of Nutrition and Health, University of Aberdeen, Aberdeen AB21 9SB, UK.
authors.forename: Claire L
authors.initials: CL
authors.lastname: Fyfe
authors.forename: Joanne
authors.initials: J
authors.lastname: Stewart
authors.forename: Sandra D
authors.initials: SD
authors.lastname: Murison
authors.forename: Diane M
authors.initials: DM
authors.lastname: Jackson
authors.forename: Kellie
authors.initials: K
authors.lastname: Rance
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
authors.forename: Graham W
authors.initials: GW
authors.lastname: Horgan
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Johnstone
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004032:Diet / Q000706:statistics & numerical data*; D015930:Diet Records; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D018977:Micronutrients / Q000008:administration & dosage*; D008875:Middle Aged; D015596:Nutrition Assessment; D012606:Scotland; D012621:Seasons; D017678:Sex Distribution; D013997:Time Factors; D055815:Young Adult
chemical_list: D018977:Micronutrients