Investigating the Early Markers of Weight Loss
Condition: Weight Loss; Appetitive Behavior; Obesity
MeSH terms: Body Weight; Weight Loss
Study type: Interventional

Summary: 
      The study will include 30 women randomized in two distinct groups: G1: Slow weight loss and
      G2: Rapid weight loss . The total duration of the program will be different for each group,
      being over 20 and 10 weeks for G1 and G2, respectively, in attempt to match the groups on
      amount of weight loss (approximately 20 pounds per subject). Participants who meet the
      inclusion criteria will be randomized to rapid or slow weight loss groups. The energy
      deprivation of the rapid and slow weight loss will be in -1000 kcal/day and -500 kcal/day,
      respectively. Calculated based on the baseline resting energy expenditure (REE; determined by
      indirect calorimetry) and their physical activity level measured for one week. The diet
      macronutrient composition will be personalized for each participant based on the results of
      2-day energy intake at preliminary session, measured with food items selected from a
      validated food menu. Individuals will be instructed to maintain the level of energy
      restriction and macronutrient composition during the diet period, however they will be able
      to do food exchanges, based on the Canadian Diabetes Association system. It will be measured
      participant's body weight, body compositions, appetite sensations, resting energy
      expenditure, energy intake, palatability, olfactory performance, food reward, food
      reinforcement and impulsivity. Participants will have 7 sessions in total: 1 preliminary,
      baseline, 7 days of intervention, 3 follow ups and final assessment.
    

Detailed description: 
      Preliminary session (approximately 3 hours) During this visit, participants will receive the
      consent form and they will be informed of the experimental procedures, which will be used
      during each experimental session, as well as the equipment that will be used to obtain the
      necessary data. Their weight (digital scale), height (standard stadiometer), waist
      circumference and blood pressure will be measured at the start the session. If participants
      match the study inclusion criteria, they will have an equal chance of being assigned to one
      of two groups; one intervention will last 10 weeks and the second intervention will last 20
      weeks but both groups are designed to produce the same amount of weight loss. We will measure
      their resting metabolism (the energy you use while at rest) (indirect calorimetry). We will
      then serve a breakfast according to their personal choice and we will recommend them to "eat
      as much or as little as they want" in 15 minutes. Then, they will be asked to complete other
      questionnaires the Yale Food Addition Questionnaire that measure personality traits and food
      addiction symptoms, respectively. This session will be used to determine their breakfast
      during the experimental sessions and to determine the macronutrient composition (percentage
      of carbohydrates, fat and protein) will be adopted for them during their diet. They will be
      asked to fill a food menu and choose your meals for the rest of your day as well as for the
      day that will follow their visit. We will provide all your food items in lunch boxes and
      individual bags. They will be able to carry these items and they will be instructed to eat
      only the items that they have chosen for these 2 days. Lastly, they will be asked to wear a
      biaxial accelerometer around your upper arm, 24 hours per day during 7 days, including when
      sleeping, but should remove it when in contact with water (for instance, when bathing,
      showering or swimming) because this device is not waterproof.

      Second Visit: (approximately 1 hour) Upon completion of the preliminary phase, participants
      will be invited to a 2nd meeting at the lab, in order to receive the dietary instructions
      related to their weight loss program. This diet is the one that you will be instructed to
      follow for the duration of the weight loss program (10 or 20 weeks depending on their group).
      The diet will be prescribed using the Canadian Food Exchange System. This method will allow
      you to select foods you enjoy during the weight loss, however in smaller quantities.

      Exchange lists are groups of foods that contain a similar mix of carbohydrates, protein, fat,
      and calories. The Canadian exchange system there are seven exchange groups: Grains &
      Starches; Fruits; Milk & Alternatives; Vegetables; Meat & Alternatives; Fats; Unlimited
      consumption.

      Within any group, participants can exchange one food serving for another. For example, in the
      Meats group, some sample foods that equal one lean meat exchange might be: 1 oz. of white
      meat chicken or turkey with no skin or 1 oz. of lean beef.

      The daily meal plan will contain foods from all seven Food Exchange lists in order to assure
      them a complete and a balanced nutrition. However, the number of portions from each group
      will be recommended based on their individual diet evaluated in the preliminary session. This
      session will also be used to clarify any potential questions that participants have regarding
      the project and the intervention.

      Third and Fourth experimental sessions (approximately 6 hours each)

      Arrival at the laboratory (12 hours fasted, at 7:30 h)

      Participants will have a total of 3 experimental sessions: before starting the diet (baseline
      measurement), 5 to 7 days after the beginning of the weight loss program and at the end of
      the weight loss program. Each of these visits will take approximately 6 hours. Here is a
      detailed description of the different methods/procedures that will be employed during each
      experimental session:

      A. Anthropometric, body composition and resting metabolic rate assessments, consumption of a
      standard breakfast and appetite measurements (Approximately 4.5 hours)-Participant's height
      and body weight will be measured as soon as they arrive in the laboratory for the
      experimental session. Their amount of body fat and muscle (by dual energy X-ray
      absorptiometry) and your resting metabolism (by indirect calorimetry) will also be measured.
      Afterwards, we will serve breakfast to them. This meal will contain the exact amounts of each
      item that you consumed during the preliminary session. They will have 15 minutes to consume
      this entire meal. Additionally, they will be asked to answer 4 specific questions that
      quantify appetite sensations (desire to eat, hunger, fullness and prospective food
      consumption) using 100-millimeter visual analogue scales that will be administered before,
      immediately after (time 0), and every 30 minutes for 3 hours (30, 60, 90, 120, 150 and 180
      minutes) following breakfast consumption.

      B. Dual energy X-ray absorptiometry (Approximately 10 minutes): We will assess participant's
      body fat using the dual energy X-ray absorptiometry (DXA). They will be asked to wear a
      standard issue hospital gown, to lie on an examination table and do not make any movement
      during the assessment. In the meantime, a low-intensity X-ray will scan your entire body.

      C. Indirect Calorimetry (Approximately 45 minutes) - Participant's will be required to remain
      resting for 30-min during this measurement. A plexiglass hood (similar to a plastic bubble)
      will be placed over their head through which fresh air will be drawn. The expired air will be
      sampled for analysis and percentages of oxygen and carbon dioxide will be determined over the
      30-min collection period. With this measurement, we will be able to determine participant's
      resting rate of oxygen consumption. With this information we can calculate their resting rate
      of energy expenditure. There are no risks associated with this procedure.

      D. Leeds Food Preference Questionnaire (LFPQ) (Approximately 15 minutes)-This task provides
      measures of the wanting and liking for an array of food images presented to participants on a
      computer screen. During the test, each food image is presented with every other food image in
      turn. Participants will be instructed to select the food you "most want to eat now" during
      each trial. Participants will also need to rate each of the visual food cues in turn on a
      100-millimeter visual analogue scale (anchored by Not at all-Extremely), based on the
      following questions: "how much do you want some of this food now?" and "How pleasant would it
      be to experience a mouthful of this food now", respectively. This task will be completed at
      60 minutes and 180 minutes post-breakfast consumption, immediately following lunch
      consumption.

      E. Behavioral Choice Task - For this task, participants will sit in front of a laptop which
      will present to them 2 slot machine games: one is to earn points towards your preferred snack
      food and the other is to earn points towards your favorite fruit/vegetable. They will then
      have the opportunity to earn points towards your favorite snack and/or favorite
      fruit/vegetable by playing these different slot machines. To earn points, they must press a
      button on the mouse when the cursor is placed over the slot machine of choice, which then
      starts that slot machine. Points are then earned when all three objects on the screen match.
      This task will be completed immediately following the Leeds Food Preference Questionnaire
      administered at 180 minutes post-breakfast consumption and the amount of snack/ fruit earned
      during the game will be served with their lunch.

      F. Olfactory (smell) capacity measurement -Participants will be required to complete 3
      different odor tests. First, a set of 3 capsules will be subsequently presented to them and
      they must identify which of the 3 capsules presents an odor (the other 2 capsules are
      odorless). Second, a set of 3 capsules will be subsequently presented to them and them must
      identify which of the 3 capsules presents a different odor (the other 2 capsules will have
      the same odor). Finally, they will be required to identify the correct odor released by the
      capsule. Examples of some of the odors include rose, marker, banana, and grass.

      G. Assessment of food intake at lunch (Approximately 30 minutes)-The energy intake of lunch
      will be measured with a test meal administered in the end of your experimental sessions
      (approximately 4 hours upon you arrive at the laboratory). This test meal will be selected
      from a food menu, which contains 57 different food and beverage items. Once the selected food
      items are prepared and served, participants will have 30 minutes to consume "as much or as
      little as they want" from the foods that you selected on the menu. The selected food items
      will then be prepared, measured and placed for you to eat at the lab.

      Four follow-up sessions (approximately 90 minutes each) During the intervention, participants
      will be asked to visit the laboratory for a bi-weekly or a monthly evaluation (depending on
      the group to which you will be randomized). During these follow-up sessions we will evaluate
      participant's weight, resting metabolic rate and fasting appetite. As soon as they arrive at
      the laboratory (12 hours fasted), we will measure their current weight, appetite and resting
      metabolic rate. We will offer breakfast before participants leave. In total, participants
      will complete 3 follow-up visits.

      FINAL EXPERIMENTAL SESSION (Approx. 6 hours) The same protocol applied at the baseline
      experimental session will be repeated after the intervention.
    

Intervention name(s): dieting
Intervention type(s): Behavioral
Intervention description(s): The minimum amount of caloric intake will be pre-set in 1200 kcal for the both groups, in order to avoid micronutrient deficiencies during the intervention. The diet macronutrient composition will be personalized for each participant based on the results of 2-day energy intake at preliminary session, measured with food items selected from a validated food menu. Individuals will be instructed to maintain the level of energy restriction and macronutrient composition during the diet period, however they will be able to do food exchanges, based on the Canadian Diabetes Association system . This method allows individuals to select foods they enjoy during the weight loss, however in smaller quantities.
Other intervention name(s): Caloric restriction (-500 kcal/day); Caloric restriction (-1000 kcal/day)
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: clinical trial
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: energy expenditure; weight loss; appetite; impulsivity; food reward