Metabolic Effects of Almond in the Longer-term Study
Condition: Obesity
MeSH terms: Body Weight
Study type: Interventional

Summary: 
      Identifying snacks that do not contribute to positive energy balance is crucial in weight
      management. The satiating effects of almonds, coupled with their convenience and palatability
      make them a promising weight management aid. Therefore, this study aimed to examine the
      effects of almond consumption with meals versus snacks on outcomes such as appetite, energy
      intake, body weight, as well as blood glucose, insulin and lipid responses.
    

Detailed description: 
      Experiment protocol and measurements

      i) Oral glucose tolerance test (OGTT) sessions

      At baseline, participants attended a session where a standard OGTT with drinks containing 75
      grams dextrose was performed following an overnight fasting. Serum glucose and insulin
      concentrations were measured at 0 and 120 minutes of the session. During the same session,
      height, weight (Tanita), body fat (air displacement plethysmography, BOD POD), waist
      circumference, and blood pressure were measured. Participants also completed a 24-hour
      dietary recall using a multi-pass interview method and standard questionnaires that assessed
      personality, eating behavior and habitual physical activity levels during the OGTT session.
      After the completion of this session, participants were asked to record their hourly appetite
      sensations, measured as "hunger", "fullness" and "desire to eat" on visual analog scales,
      during waking hours for a day before attending the next (clinical) visit. Participants
      repeated this session after four weeks of almond consumption.

      ii) Acute feeding sessions

      Within a week following the OGTT session, participants returned for an acute-feeding session,
      after an overnight fasting of at least 10 hours. This session began between 7:00 am and 8:00
      am, and lasted for approximately 515 minutes. Upon arrival, an indwelling arm catheter was
      placed in the upper arm for blood sample collection. Participants rested for 15 minutes after
      catheter placement, before a baseline blood sample was drawn. Immediately after the first
      blood sample collection, a standard breakfast was served, and participants were instructed to
      consume the entire portion within 10 minutes. Subsequent blood samplings were performed at
      15, 45, 60, 90, 120, 180, and 240 minutes after the breakfast, before a standard lunch was
      provided to the participants. Again, participants were given 10 minutes to consume the lunch,
      before blood samples were taken at similar intervals again (at 265, 295, 310, 340, 370, 430,
      and 490 minutes of the session). Participants randomized into the BF and LN groups received
      43 grams of almonds together with their meals, while the MS and AS groups consumed 43 grams
      of almonds 120 minutes after breakfast and lunch respectively. Participants also recorded
      their "hunger", "fullness", and "desire to eat" sensations when blood samples were taken.
      During the acute-feeding session, activities that may alter appetite sensations (e.g.
      sleeping and watching movies containing food cues) were prohibited. Postprandial glucose,
      insulin and triacylglycerol concentrations were measured for all 15 samples collected from
      each participant. Participants in all almond groups group were also asked to rate their
      likings for the almonds they ingested using a general label magnitude scale, and their action
      responses to almonds using the "food action rating scale", a visual analog scale ranging from
      "I would eat the almonds only if I were forced to" to "I would eat this food every
      opportunity I had" anchored to the 2 extremes. This session was repeated again after four
      weeks of almond supplementation.

      iii) Weekly follow-ups

      Following the baseline acute-feeding session, participants were asked to consume 43 grams of
      almonds every day at times based on their group randomization. The CL group was instructed to
      avoid all nuts and seeds in the diet during the study period. All almonds were dry-roasted
      and lightly salted, and were pre-weighed and per-packaged for convenience. Except for the
      permission to adjust dietary intake due to almond supplement, participants were asked to
      maintain their dietary intakes and physical activity levels. A ruse (breath analysis) was
      introduced in order to enhance the compliance of participants to consuming almonds at the
      designated times of day. Compliance to almond consumption was assessed through fasting plasma
      α-tocopherol. Participants attended weekly visit (week-1, 2 and 3) after an overnight
      fasting, during which body weight was recorded and compliance to study protocol reinforced.
      During the week-2 visit, participants were also asked to complete a 24-hour dietary intake
      assessment using the multi-pass interview method and appetite sensation ratings on VAS at
      every waking hour for a day. On week-4, participants returned for OGTT and acute-feeding
      sessions as described above. The study protocol was approved by the Purdue University
      Institutional Review Board.
    

Intervention name(s): Almonds 43g/day
Intervention type(s): Dietary Supplement
Intervention description(s): 43 grams of almonds were supplemented to the 4 intervention arms but eaten at different times of day (with meals or alone as snacks) for 4 weeks. Control group was asked to avoid all nuts/seeds during the study period
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Almonds; Body weight; Snacking