Pilot Project to Examine the Effects of Exercise on Nocturnal Lipolysis in Men and Women
Condition: Healthy
Study type: Observational

Summary: 
      The goal of this proof of concept/feasibility study is to use rigorous methodology to explore
      links between daytime energy status and nocturnal fat metabolism in healthy adults.
    

Detailed description: 
      This primary goal of this pilot project is to obtain preliminary data demonstrating the
      feasibility of measuring lipolysis and fat oxidation during sleep in adult human subjects
      using microdialysis, stable isotope labeling techniques, and whole-room indirect calorimetry.
      The results of this study will be used in grant applications to perform definitive studies
      using these methods. The long term goal of this line of research is to explore the mechanisms
      responsible for sex based differences in the effectiveness of physical activity as an
      approach to weight loss. Previous longitudinal data have shown that in normal weight and
      obese individuals, for any given increase in physical activity, there is a significantly
      greater loss of fat mass in men relative to women [Westerterp, 1997]. These data need to be
      reconciled, however, with the wealth of data demonstrating that during exercise, women
      release and oxidize fat more readily than men [Horton, 2009; Horton 1998, Moro 2007]. This
      phenomenon seems counterintuitive, given that men have less body fat than women and are able
      to lose more body fat than women when beginning a weight loss program [Bjorntorp, 2007].
      Recent data suggests a mechanism to explain this paradox. Specifically, in obese subjects,
      24-hour fat oxidation increased following a daytime bout of exercise, and this increase
      occurred in men only and was driven by a significant increase in fat oxidation not during the
      day but rather during sleep the night following exercise [Bergouignan, 2014]. Since the
      predominant source of fuel during sleep is free fatty acids (FFA) released from adipose
      tissue (i.e., lipolysis), it may be that enhanced sleeping lipolysis is a key factor in how
      exercise stimulates fat oxidation and thus greater fat loss in males vs. females over time.

      The primary objective of the proposed study is to demonstrate the feasibility of measuring
      nocturnal whole-body and regional lipolysis by using stable isotope techniques and
      microdialysis of subcutaneous abdominal adipose tissue respectively with the long term goal
      of determining the effects of acute exercise during the daytime on rates of lipolysis at
      night in men and women. A secondary objective of this study is to determine if nocturnal
      regional lipolysis measured by microdialysis of subcutaneous abdominal adipose tissue and
      whole body lipolysis measured by a stable glycerol isotope infusion are related to dietary
      and whole body fat oxidation measured by stable isotope labelled fatty acid and whole-room
      calorimetry, respectively. Finally, the study aims to determine if sleep quality parameters
      measured by EEG and wrist actigraphy correlate with measures of nocturnal fat oxidation and
      lipolysis (regional and whole body)
    

Observational model: Case-Only
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Healthy Adults
      
Keywords: Volunteers