The Effect of Irregular Meal Pattern on Nitrogen Balance in Healthy Normal-weight Women
Condition: Nitrogen Balance
Study type: Interventional

Summary: 
      Nitrogen balance (NB) is defined as the net difference between the intake of nitrogen (input)
      and its excretion (output). NB was considered as an indicator of the catabolic stress level.
      Thus, a negative NB can occur as a result of catabolism which leads to muscle mass loss. It
      was demonstrated that there is a relationship between meal frequency and N loss. Irregular
      meal patterns have been considered as a possible new risk factor for obesity and its
      consequences, specifically cardiovascular disease and metabolic syndromes. As the regular
      meal pattern is associated with higher BMI in many observational studies and has an impact on
      the metabolism of carbohydrates and lipids, it could also affect protein metabolism.

      Eating irregularly can cause chrono-disruption because the changes in the timing of food
      intake as a consequence may also alter the chrono-biological or circadian rhythm of many
      hormones such as insulin, glucagon, adiponectin, leptin and gastric acid secretion. From
      this, investigators hypothesized that following an irregular meal pattern can negatively
      influence the N balance and circadian rhythm.
    

Detailed description: 
      The study will have a crossover randomised, non blinded two meal pattern design with healthy
      adult female volunteers recruited from Nottingham, UK and the surrounding area.

      Firstly, a screening visit lasting approximately an hour will be arranged and height, weight,
      and waist circumference will be measured following standard procedures (eg without shoes,
      wearing light clothes). Body composition will be obtained using skinfold thickness at four
      sites (triceps, biceps, subscapular and suprailiac). A blood sample (8 ml) will be obtained
      for routine blood investigation. A number of questionnaires will be completed to assess
      medical health, sleep duration, physical activity levels, eating behaviour and depression. On
      departure, subjects will be asked to complete a 4 days food diary.

      The present study will last for 5 weeks. During the first week participants will be required
      to adopt one of two meal patterns, followed by a three week washout period, in which they
      will be allowed to return to their habitual diet, before undertaking a second week
      intervention following the second meal pattern. These meal patterns will consist of consuming
      1) a regular meal pattern of 6 daily meals for two weeks, or 2) an irregular one consisting
      of consuming a different number of meals every day (between 3 and 9). Investigators propose
      to provide an iso-energetic diet containing identical foods with macronutrient composition
      (as a percentage of total energy per day) of 50% carbohydrate, 35% fat, and 15% protein for
      both patterns. All foods to be consumed during the study (1st and 5th week) will be provided
      free of charge. These will comprise foods commonly consumed in the British diet and will be
      consumed in amounts designed to keep body weight constant during the study. Participants will
      complete a food compliance diary over the study period. Physical activity will be captured by
      BodyMedia SenseWear armband to ensure that participants have a similar physical activity
      level in both intervention periods. This device records and analyses physiological
      parameters, and uses algorithms to report daily movement, calories burned, degree of physical
      activity and steps taken. It will be placed on the back of the upper left arm (the tricep).
      The Armband logo must face upward towards the shoulder and the silver sensors on the
      underside of the Armband will be in contact with skin.

      Participants will be advised to consume a standardized evening meal based on their food
      record on the day before the start of each intervention and to provide 7, 24-h urine samples
      over the course of each intervention period. All urine was collected from study participants
      for 24 hr beginning at 7 am. Urine will be collected into 7 plastic urine containers without
      preservative. 5 ml will be stored from the well-mixed 24-h urine collection and analysed for
      urinary urea. In addition, they will be advised to wear a wireless iButton data logger to
      measure the wrist temperature in order to assess the circadian rhythm. The iButtons will be
      programmed to sample every 10 min, and will be attached to a double-sided cotton sport wrist
      band usingVelcro®, with the sensor face of the iButton being placed over the inside of the
      wrist, on the radial artery of the non-dominant hand.

      Finally, subjective appetite (including hunger, fullness and desire to eat) will be assessed
      using visual analogue scales (VAS) during the intervention. Participants will be provided
      with a booklet in which to record the subjective appetite before and after each single meal
      on day 7 during both intervention periods when the subjects consume 6 meals/d during each
      intervention.
    

Intervention name(s): Regular meal pattern; Irregular meal pattern
Intervention type(s): Other; Other
Intervention description(s): 6 meals every day; It consists of consuming a different number of meals every day (between 3 and 9).
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Prevention