Postprandial Metabolic Responses to Sustainable and Non-Sustainable Meals in Healthy Young Men

The THERMOS‐LUNCH study (Thermogenesis, Hydration, Environmental Impact, RespiratoryQuotient, Meals, Substrate Oxidation and Sustainability after Lunch in UniversityStudents: a Nutritional Crossover Study in Healthy Subjects) was a randomised,two‐period, two‐sequence crossover intervention study conducted in healthy maleuniversity students. The study compared two standardised lunch meals that differed innutritional quality and estimated environmental impact: a healthy and sustainable mealand a less healthy and non‐sustainable comparison meal. Participants were randomlyassigned to one of two intervention sequences: the healthy and sustainable meal followedby the comparison meal, or the comparison meal followed by the healthy and sustainablemeal. The two experimental visits were separated by a 7‐day washout period.During each experimental visit, postprandial metabolic responses were assessed usingportable indirect calorimetry. Oxygen consumption, carbon dioxide production, respiratoryexchange ratio, energy expenditure, diet‐induced thermogenesis and substrate oxidationwere measured during the fasting baseline period and over the 4‐hour postprandial period.Subjective appetite and satiety sensations were assessed repeatedly using 100‐millimetrevisual analogue scales. Hydration‐related measures included total fluid intake, urinevolume, urine colour and urine specific gravity measured using a digital refractometer.Total urinary nitrogen, obtained from the 24‐hour urine collection, was used to accountfor protein metabolism in substrate‐oxidation calculations, while urinary creatinine wasused as a quality‐control marker for the plausibility and completeness of the 24‐hoururine collection.