This study evaluates eating behavior and metabolic responses following consumption of a high-fat high-energy meal in healthy underweight and normal-weight adults. The primary research question is: Do healthy underweight individuals exhibit different eating and metabolic responses compared with normal-weight adults following consumption of a high-fat high-energy meal?
Healthy underweight individuals have a body mass index below the normal range in the absence of a medical condition, food aversion, food insecurity, or evidence of unusually high levels of physical activity. Although the environmental factors contributing to their lower body mass index are not fully understood, these individuals may represent a phenotype resistant to the obesogenic environment. If so, the biological mechanisms underlying this resistance remain poorly understood. Such mechanisms must ultimately influence energy expenditure, energy intake, or both. This study will compare metabolic responses and eating behavior during fasting and following consumption of a high-fat, high-energy meal in healthy underweight and normal-weight adults. Eating behavior will be assessed through measures of food liking, subjective appetite perceptions, and ad libitum energy intake. Metabolic responses will include assessments of energy expenditure, substrate oxidation, and circulating metabolites and hormones. We hypothesize that healthy underweight individuals will exhibit greater postprandial satiety and lower ad libitum energy intake than normal-weight adults.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
59
Following an overnight fast, participants will consume a standardized high-fat high-energy meal under controlled laboratory conditions. During the subsequent postprandial period, appetite sensations, energy expenditure, circulating biomarkers, and food intake will be assessed. Food intake will be evaluated using an ad libitum meal test consisting of two sequential phases involving foods with different sensory and nutritional characteristics.
Avda. Libertador Bernardo O´Higgins 340
Santiago, Santiago Metropolitan, Chile
Total ad-libitum energy intake
Total energy intake consumed during the ad libitum feeding test. Participants will be provided with a selection of foods and instructed to eat ad libitum until comfortably satiated. The weight of each food item will be recorded before and after consumption, and intake will be determined from the difference. Total energy intake (kcal) will be calculated from the nutrient composition of the foods consumed using standard energy conversion factors.
Time frame: The feeding test will be conducted 6.5 hours after the high-fat, high-energy meal.
Food liking
Food liking will be assessed in the fasted state using a computerized questionnaire comprising 67 foods commonly available in retail food stores. The food list includes a wide variety of items differing in energy density, macronutrient composition, degree of processing, and sensory characteristics, including fruits, vegetables, legumes, grains, dairy products, meats, nuts, snack foods, and desserts. Images of the foods will be presented individually on a computer screen, and participants will rate their liking of each item using a 9-point Likert scale ranging from 1 ("dislike extremely") to 9 ("like extremely").
Time frame: Measured during the screening visit.
Body composition
Whole-body and regional body composition assessed by dual-energy X-ray absorptiometry (DXA).
Time frame: Measured during a dedicated body composition assessment visit.
Subjective appetite sensations
Appetite sensations will be assessed at fasting and during the postprandial period using 100-mm visual analogue scales. Participants will rate hunger, fullness, desire to eat, and prospective food consumption. Scores will be quantified as the distance (mm) from the left anchor, with higher scores indicating greater intensity of the rated sensation.
Time frame: Repeatedly measured during the metabolic test before and following consumption of the high-fat, high-energy meal.
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Energy expenditure and fuel oxidation
Energy expenditure and fuel oxidation will be assessed in the fasted state and during the postprandial period using indirect calorimetry. Oxygen consumption and carbon dioxide production will be measured under standardized conditions using a ventilated hood system. Energy expenditure will be calculated from respiratory gas exchange data using standard equations. Rates of carbohydrate and fat oxidation will be estimated from respiratory gas exchange measurements, with adjustments for urinary nitrogen excretion using standard stoichiometric equations.
Time frame: Repeatedly measured during the metabolic test before and following consumption of the high-fat, high-energy meal.
Circulating metabolite and hormonal concentrations
Blood samples obtained in the fasted state and throughout the postprandial period will be analyzed for concentrations of glucose, free fatty acids, β-hydroxybutyrate, triglycerides, and insulin. Concentrations will be determined using validated clinical chemistry and immunoassay methods.
Time frame: Repeatedly measured during the metabolic test before and following consumption of the high-fat, high-energy meal.