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Recommendations Summary

EE: Fasting in Healthy and Non-Critically Ill 2014

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.


  • Recommendation(s)

    EE: Fasting Requirements in Healthy Adults

    Prior to measurement of resting metabolic rate (RMR), the registered dietitian nutritionist (RDN) should ensure a healthy adult has fasted at least seven hours to minimize the thermic effect of feeding (TEF). Research in healthy adults indicates that the TEF dissipates depending on the amount of calories consumed. The TEF for meals containing approximately 450kcal to 1, 500kcal is still present at three to five hours. One study reported that the thermic effect of consuming 1, 300kcal was negligible after seven hours post-consumption. 

    Rating: Fair
    Imperative

    EE: Exceptions to Fasting Requirements in Healthy Adults

    If a seven-hour fast is not clinically feasible prior to measurement of RMR in a healthy adult, the RDN should instruct the individual that a small meal (300kcal or less) may be consumed four hours prior to the measurement. One study reported that the TEF, when consuming approximately 300kcal, was negligible after 3.5 hours post-consumption in healthy adults.

    Rating: Fair
    Conditional

    • Risks/Harms of Implementing This Recommendation

      Clinical judgment is needed to determine if fasting is contraindicated.

    • Conditions of Application

      • These recommendations do not address the effect of alcohol, non-caloric beverages or water on RMR, independent of meals
      • These recommendations do not consider the effect of continuous feedings, macronutrient composition, overfeeding, etc. on RMR
      • Clinical judgment should be used in applying these recommendations to healthy children and non-critically ill children and adults, due to no evidence in these populations
      • An overnight fast is preferred
      • The recommendation EE: Exceptions to Fasting Requirements for Healthy Adults applies to individuals for whom extended fasting is not possible (e.g., individuals on medications requiring food or caloric beverages, etc.).

    • Potential Costs Associated with Application

      There are no obvious costs that may be associated with the application of these recommendations.

    • Recommendation Narrative

      A total of 13 studies were included in the evidence analysis for this recommendation:

      • One positive-quality randomized crossover trial (Segal and Gutin, 1983)
      • One positive-quality non-randomized crossover trial (Kinabo et al, 1990) 
      • Five neutral-quality randomized crossover trials (Raben et al, 2003; Segal et al, 1992; Weststrate, Hautvast, 1990; Weststrate et al, 1989; Weststrate, Wunnink, 1990)
      • Four neutral-quality non-randomized crossover trials (Belko et al, 1987; Bielinski et al, 1985; Bissoli et al, 1999; Poehlman et al, 1988) 
      • One neutral-quality diagnostic, validity or reliability study (Blond, et al, 2010)
      • One neutral-quality before-and-after study (Levine et al, 2000).
      EE: Fasting Requirements in Healthy Adults and EE: Exceptions to Fasting Requirements in Healthy Adults
      • A total of 13 studies provide evidence that consuming meals containing approximately 450kcal to 1, 500kcal increases metabolic rate in healthy adults for at least three to five hours, however the majority of studies did not include a measurement period long enough to observe a return to baseline levels
      • The TEF dissipates depending on the amount of calories consumed. One study reported that the thermic effect of consuming approximately 300kcal was negligible after 3.5 hours post-consumption and another study reported that the thermic effect of consuming 1, 300kcal was negligible after seven hours post-consumption.
      • Additional research is needed in this area
      • Evidence is based on the following: Belko et al, 1987; Bielinski et al, 1985; Bissoli et al, 1999; Blond, et al, 2010; Kinabo et al, 1990; Levine et al, 2000; Poehlman et al, 1988; Raben et al, 2003; Segal and Gutin, 1983; Segal et al, 1992; Weststrate, Hautvast, 1990; Weststrate et al, 1989; Weststrate, Wunnink, 1990.

    • Recommendation Strength Rationale

      Conclusion statement supporting these recommendations is grade III.

    • Minority Opinions

      None.