title: Number of 24-hour diet recalls needed to estimate energy intake.
abstract: OBJECTIVE
  Twenty-four-hour diet recall interviews (24HRs) are used to assess diet and to validate other diet assessment instruments. Therefore it is important to know how many 24HRs are required to describe an individual's intake.
  
  
  METHODS
  Seventy-nine middle-aged white women completed seven 24HRs over a 14-day period, during which energy expenditure (EE) was determined by the doubly labeled water method (DLW). Mean daily intakes were compared to DLW-derived EE using paired t tests. Linear mixed models were used to evaluate the effect of call sequence and day of the week on 24HR-derived energy intake while adjusting for education, relative body weight, social desirability, and an interaction between call sequence and social desirability.
  
  
  RESULTS
  Mean EE from DLW was 2115 kcal/day. Adjusted 24HR-derived energy intake was lowest at call 1 (1501 kcal/day); significantly higher energy intake was observed at calls 2 and 3 (2246 and 2315 kcal/day, respectively). Energy intake on Friday was significantly lower than on Sunday. Averaging energy intake from the first two calls better approximated true energy expenditure than did the first call, and averaging the first three calls further improved the estimate (p=0.02 for both comparisons). Additional calls did not improve estimation.
  
  
  CONCLUSIONS
  Energy intake is underreported on the first 24HR. Three 24HRs appear optimal for estimating energy intake.
authors: Division of Preventive and Behavioral Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655, USA. Yunsheng.Ma@umassmed.edu
authors: Yunsheng
authors: Y
authors: Ma
authors: Barbara C
authors: BC
authors: Olendzki
authors: Sherry L
authors: SL
authors: Pagoto
authors: Thomas G
authors: TG
authors: Hurley
authors: Robert P
authors: RP
authors: Magner
authors: Ira S
authors: IS
authors: Ockene
authors: Kristin L
authors: KL
authors: Schneider
authors: Philip A
authors: PA
authors: Merriam
authors: James R
authors: JR
authors: Hébert
mesh_terms: D015992:Body Mass Index; D003625:Data Collection / Q000379:methods*; D004032:Diet; D002149:Energy Intake; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D011939:Mental Recall; D008875:Middle Aged; D012959:Socioeconomic Factors