title: Contribution of energy density and food quantity to short-term fluctuations of energy intake in normal weight and obese subjects.
abstract: BACKGROUND
  In normal weight subjects it is known that day-to-day energy intake (EI) can vary substantially while this question has not been examined in obese subjects. From acute feeding experiments one would assume that these perturbations are mainly due to differences in food energy density (ED). However, food quantity (FQ) during single meals, number of meals, cognitive and sensory mechanisms may also contribute to the modification of EI.
  
  
  OBJECTIVE
  To obtain more detailed information about day-to-day variations of food intake food diaries recorded during 10 consecutive days of 280 obese and 100 normal weight subjects were examined.
  
  
  RESULTS
  The chronological analysis shows a fairly constant pattern for EI, FQ and ED in both groups. The group analysis, however, masks individual fluctuations since the coefficients of variation were between 20 and 24% for the three parameters, respectively. This corresponds to a range of 1,200 kcal. Sixty-five percent can be accounted for changes in FQ and 35% as the result of variations in ED. Snacks between main meals account for 20% of daily EI but only 10% of FQ. Furthermore, snack EI is not compensated during main meals.
  
  
  CONCLUSIONS
  Small day-to-day changes of EI are due to increased meal quantities while greater fluctuations are also due to higher food ED. The present data suggest that modification of FQ by cognitive and sensory factors plays an important role in the variation of daily EI under real life conditions with no major difference between normal weight and obese subjects.
authors: Else-Kröner-Fresenius Center of Nutritional Medicine, Technical University of Munich, Ismaninger Strasse 22, 81675, Munich, Germany. volker.schusdziarra@lrz.tum.de
authors: Volker
authors: V
authors: Schusdziarra
authors: Margit
authors: M
authors: Hausmann
authors: Claudia
authors: C
authors: Wittke
authors: Johanna
authors: J
authors: Mittermeier
authors: Marietta
authors: M
authors: Kellner
authors: Stefan
authors: S
authors: Wagenpfeil
authors: Johannes
authors: J
authors: Erdmann
mesh_terms: D000328:Adult; D015992:Body Mass Index; D004435:Eating; D002149:Energy Intake; D005260:Female; D005502:Food; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D013997:Time Factors