Bed Rest, Space Analogue
Conditions
Keywords
energy intake, energy density, satiety
Brief summary
Brief summary: This study is conducted in the context of a 60 days strict bed-rest study with 6° head-down-tilt (HDT) body position. Food intake can be challenging during bed-rest due to loss of appetite and constantly feeling full. The study aims to assess whether or not energy intake varies during a meal when the energy density of a meal is increased by the fat content. This experiment follows a crossover design with repeated measures within subjects. The order of experimental conditions is balanced among participants and sex, and the assignment of orders to participants is randomly. On each test day, participants are provided with breakfast, lunch, and dinner as usual. Across test days, the ED of breakfast (24 participants) or lunch (24 participants) is modified to two levels: the standard level and an increased level (+ 0.42 kcal/g compared to the standard). The meals are adjusted in energy density without noticeable changes in appearance or taste. These meals have identical ingredients, but the macronutrient proportions are modified. Entrées with increased fat content are prepared by incorporating neutral-tasting vegetable oil into the standard recipes. Participants receive their meals and are given the flexibility to eat ad libitum for 45 minutes. To comply with the strict bed rest rules, the next meal will be used for counterbalancing total energy intake over the day if necessary. In case of problems, a nutrient drink could be used to assure the requested total energy intake in order to maintain body weight.The experiments are conducted during 4 campaigns, each campaign consisting of 12 participants.
Interventions
OTHERDietary intervention with manipulation of the energy density
Dietary intervention with manipulation of the energy density either during breakfast or during lunch
Sponsors
DLR German Aerospace Center
University Hospital Tuebingen
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
The meals are adjusted in energy density without noticeable changes in appearance or taste. These meals have identical ingredients, but the macronutrient proportions are modified. It can be not ruled out that some participants may recognize differences of the meals.
Intervention model description
This is a repeated measures randomized controlled cross-over design with an additional randomization on block: 1\) Randomized controlled cross-over experiments are conducted at the end of the first week of the bedrest (days 6-8) and at the end of the bed rest (days 51-53). In total, every participant is tested on 4 days, receiving either the control test meal or the meal with increased fat content in a 1000 ml bowl. 2) Additionally, the 4 campaigns are randomized on block so that either the breakfast or the lunch will be manipulated.
Eligibility
Sex/Gender
ALL
Age
18 Years to 99 Years
Healthy volunteers
Yes
Inclusion criteria
* Physically and mentally healthy test subjects that declare their willingness to participate in the entire study and successfully pass the psychological and medical screening * Aged between 24 and 55 years * Body mass index between 18 to 28 kg/m2 * Body height between 153 to 190 cm (+/- 2 cm) * Signed informed consent * Demonstrable medical insurance and official certificate of absence of criminal record * No less than 2 SD below the average normal bone mineral density (measured by dual-energy x-ray absorptiometry) for hip and lumbar spine (i.e., mean peak bone mineral density of Caucasian, sex-matched young adults) denoted by T-score (T-score \> -2) * Demonstrable dentist certificate * Hormonal contraception for female participants is allowed, but details (manufacturer, doses, dates) must be reported
Exclusion criteria
Candidate subject
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Energy intake in kcal | Measurments taken at days 6, 8, 51 and 53 in the 60 days head down tilt period. | Energy intake is calculated by measuring the amount of food before and after the experiment and precalculation of the energy content of the meals |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Amount of food intake in g | Measurments taken at days 6, 8, 51 and 53 in the 60 days head down tilt period. | The amount of food intake is calculated by measuring the amount of food before and after the experiment |
| Composite appetite score measured by 10 cm visual analogue scales (VAS) | Measurments taken at days 6, 8, 51 and 53 in the 60 days head down tilt period before the meal, 30 minutes, 45 minutes and 60 minutes after the meal and directly before the next meal (either lunch or dinner) | Appetite perception is measured using validated 100 mm VAS for hunger, satisfaction, fullness, and prospective food consumption (Flint et al., 2000). The composite score is calculated as follows: (\[hunger + prospective food consumption + (100-fullness) + (100-satisfaction)\]/4) by Stubbs et al., 2000 |
| Visual analogue scale for perception of portion size | Measurments taken at days 6, 8, 51 and 53 in the 60 days head down tilt period before the meal, 30 minutes, 45 minutes and 60 minutes after the meal and directly before the next meal (either lunch or dinner) | Portion size is measured using a 100 mm VAS. |
| Emotional response | Measurments taken at days 6, 8, 51 and 53 in the 60 days head down tilt period before the meal, 30 minutes and 60 minutes after the meal and directly before the next meal (either lunch or dinner) | Emotional response is used using the Self assessment manikin (Bradley & Lang, 1994) |
| Number of participants assigned to countermeasures for consequences of long-term bed rest | Allocation to countermeasure test arms is done ahead of the bed rest study, at least 4 weeks ahead bed rest. | During bed rest, the participants are allocated to 4 arms of different countermeasures for consequences of long-term bed red which is independent of this food study. These countermeasures include: Arm 1: Electrical Muscle Stimulation; Arm 2: Proprioceptive Training; Arm 3: Exercise plus proprioceptive Training; Arm 4: Control. This information on bed rest countermeasure will be added as a co-variate. |
Countries
Germany
Outcome results
None listed