This randomized crossover study evaluated the acute postprandial metabolic and hydration responses to two standardized lunch meals differing in nutritional quality and environmental footprint in healthy young men. Each participant consumed both meals in separate experimental visits according to a randomized sequence. Postprandial oxygen consumption, carbon dioxide production, respiratory quotient, energy expenditure, diet-induced thermogenesis, substrate oxidation, satiety, and hydration-related outcomes were assessed.
The THERMOS-LUNCH study (Thermogenesis, Hydration, Environmental Impact, Respiratory Quotient, Meals, Substrate Oxidation and Sustainability after Lunch in University Students: a Nutritional Crossover Study in Healthy Subjects) was a randomised, two-period, two-sequence crossover intervention study conducted in healthy male university students. The study compared two standardised lunch meals that differed in nutritional quality and estimated environmental impact: a healthy and sustainable meal and a less healthy and non-sustainable comparison meal. Participants were randomly assigned to one of two intervention sequences: the healthy and sustainable meal followed by the comparison meal, or the comparison meal followed by the healthy and sustainable meal. The two experimental visits were separated by a 7-day washout period. During each experimental visit, postprandial metabolic responses were assessed using portable indirect calorimetry. Oxygen consumption, carbon dioxide production, respiratory exchange ratio, energy expenditure, diet-induced thermogenesis and substrate oxidation were measured during the fasting baseline period and over the 4-hour postprandial period. Subjective appetite and satiety sensations were assessed repeatedly using 100-millimetre visual analogue scales. Hydration-related measures included total fluid intake, urine volume, urine colour and urine specific gravity measured using a digital refractometer. Total urinary nitrogen, obtained from the 24-hour urine collection, was used to account for protein metabolism in substrate-oxidation calculations, while urinary creatinine was used as a quality-control marker for the plausibility and completeness of the 24-hour urine collection.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Standardized lunch meal characterized by a healthier nutritional profile and lower environmental footprint. The meal was designed to have lower carbon and water footprints compared with the non-sustainable test meal. The healthy-sustainable meal had an estimated carbon footprint of 620 g CO₂-eq and water footprint of 956.6 L, whereas the non-sustainable meal had an estimated carbon footprint of 1104 g CO₂-eq and water footprint of 1605.1 L.
Standardized lunch meal characterized by a less favorable nutritional profile and higher environmental footprint compared with the healthy-sustainable test meal. The healthy-sustainable meal had an estimated carbon footprint of 620 g CO₂-eq and water footprint of 956.6 L, whereas the non-sustainable meal had an estimated carbon footprint of 1104 g CO₂-eq and water footprint of 1605.1 L.
University of Parma, Department of Food and Drug
Parma, Parma, Italy
Diet-Induced Thermogenesis
Diet-induced thermogenesis will be calculated from postprandial energy expenditure measured by portable indirect calorimetry after consumption of each test meal.
Time frame: Baseline and 0-240 minutes after test meal consumption during each experimental visit
Respiratory Quotient
Respiratory quotient will be calculated from oxygen consumption and carbon dioxide production measured by portable indirect calorimetry at fasting baseline and during the postprandial period.
Time frame: Baseline and 0-240 minutes after test meal consumption during each experimental visit
Repeated Hunger Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Description: Hunger was assessed using a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "I am not hungry at all", to 100 millimetres, anchored by "I have never been so hungry". Higher scores indicate greater hunger and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Repeated Satiety Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Satiety was assessed using the question "How satisfied do you feel?" on a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "I feel completely empty", to 100 millimetres, anchored by "I cannot eat even a single bite". Higher scores indicate greater satiety and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Masking
NONE
Enrollment
18
Repeated Fullness Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Fullness was assessed using a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "Not at all full", to 100 millimetres, anchored by "Completely full". Higher scores indicate greater fullness and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Repeated Prospective Food Consumption Scores Assessed Using a 100-Millimetre Visual Analogue Scale
spective food consumption was assessed using the question "How much do you think you could eat?" on a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "Nothing", to 100 millimetres, anchored by "A lot". Higher scores indicate greater prospective food consumption and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Repeated Desire for Sweet Food Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Desire for sweet food was assessed using the question "Would you like to eat something sweet?" on a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "None", to 100 millimetres, anchored by "A lot". Higher scores indicate a greater desire to eat sweet food and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Repeated Desire for Salty Food Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Desire for salty food was assessed using the question "Would you like to eat something salty?" on a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "Yes, very much", to 100 millimetres, anchored by "No, not at all". Higher scores indicate a lower desire to eat salty food and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Repeated Desire for Savoury Food Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Desire for savoury food was assessed using the question "Would you like to eat something savoury?" on a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "Yes, very much", to 100 millimetres, anchored by "No, not at all". Higher scores indicate a lower desire to eat savoury food and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Repeated Desire for Fatty Food Scores Assessed Using a 100-Millimetre Visual Analogue Scale
Desire for fatty food was assessed using the question "Would you like to eat something fatty?" on a 100-millimetre visual analogue scale ranging from 0 millimetres, anchored by "Yes, very much", to 100 millimetres, anchored by "No, not at all". Higher scores indicate a lower desire to eat fatty food and do not necessarily represent a better or worse outcome. Scores were recorded repeatedly at the scheduled assessment time points during each experimental visit and are reported in millimetres.
Time frame: From the fasting assessment before the standardised breakfast to 240 minutes after consumption of the test lunch, during each experimental visit.
Total Fluid Intake
Total fluid intake was calculated as the sum of all measured fluids consumed during each experimental condition. One total value was calculated for each participant under each experimental condition and is expressed in millilitres.
Time frame: Over the 24-hour study period associated with each experimental condition.
Total 24-Hour Urine Volume
All urine produced during each 24-hour collection period was collected, and the total urine volume was measured. One total value was calculated for each participant under each experimental condition and is expressed in millilitres per 24 hours
Time frame: Over the 24-hour urine-collection period associated with each experimental condition.
Morning Spot Urine Specific Gravity
Urine specific gravity was measured in the morning spot urine sample using a digital refractometer. Triplicate measurements were averaged to obtain one value for each participant at each experimental visit. Urine specific gravity is dimensionless, and higher values indicate more concentrated urine.
Time frame: At the fasting morning urine collection before breakfast during each experimental visit.
Urine Specific Gravity of the Pooled 24-Hour Urine Collection
Urine specific gravity was measured in the pooled 24-hour urine sample using a digital refractometer. Triplicate measurements were averaged to obtain one value for each participant under each experimental condition. Urine specific gravity is dimensionless, and higher values indicate more concentrated urine.
Time frame: At completion of the 24-hour urine-collection period associated with each experimental condition.
Urine Colour Score Assessed Using the Armstrong 8-Point Urine Colour Chart
Urine colour was assessed using the Armstrong 8-point Urine Colour Chart. Scores range from 1, indicating very pale urine, to 8, indicating very dark urine. Higher scores indicate darker and generally more concentrated urine. Triplicate assessments were averaged to obtain one urine colour score for each scheduled urine sample.
Time frame: At the scheduled urine collection time points during each 24-hour experimental condition.
Urinary Nitrogen Excretion
Total urinary nitrogen will be measured from 24-hour urine samples and expressed as grams of nitrogen per 24 hours. This value will be used to estimate the contribution of protein metabolism to substrate oxidation calculations.
Time frame: 24-hour urine collection during each experimental condition
Urinary Creatinine Excretion
Urinary creatinine will be measured as a quality control marker for the plausibility and completeness of the 24-hour urine collection.
Time frame: 24-hour urine collection during each experimental condition