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Completed

NCT Number: NCT07671105

Energy Metabolism and Eating Behavior in Underweight and Normal-weight Individuals

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?

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Key information

Conditions

Healthy Underweight Behavior Behavior, Animal Feeding Behavior Food Preferences Normal Weight Adults

Age range

18 year–25 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Avda. Libertador Bernardo O´Higgins 340

Santiago, Santiago Metropolitan, Chile

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Men or women
  • Age 18-25 years
  • Stable body weight during the previous 6 months (±2 kg)
  • Healthy according to medical history and laboratory assessments
  • BMI: 15.0-<18.5 kg/m2 or 20.0-<25.0 kg/m2

Exclusion criteria

  • Pregnancy or lactation
  • Athletes or individuals engaged in high levels of physical activity, including those participating in competitive sports, structured endurance training, or physically demanding occupations.
  • Cardiovascular, liver, kidney, thyroid, or other chronic diseases requiring medical treatment
  • Conditions affecting energy metabolism or eating behavior
  • Smoking or alcohol abuse
  • Phobia or vasovagal response associated with blood draws
  • Intolerance or allergy to peanuts, chocolate, eggs, or gluten
  • Irregular menstrual cycles (>3 months without menstruation)
  • Current or previous diagnosis of eating disorders
  • Psychiatric disorders requiring antidepressant or psychotropic treatment

Additional criterion for healthy underweight participants:

  • Absence of food insecurity
  • Low body weight not attributable to eating disorders or exercise-related behaviors

Treatment and study plan

High-fat high-energy meal

Other

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.

Primary outcomes

  1. Total ad-libitum energy intake

    Time frame: The feeding test will be conducted 6.5 hours after the high-fat, high-energy meal.

    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.

Secondary outcomes

  1. Food liking

    Time frame: Measured during the screening visit.

    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").

  2. Body composition

    Time frame: Measured during a dedicated body composition assessment visit.

    Whole-body and regional body composition assessed by dual-energy X-ray absorptiometry (DXA).

  3. Subjective appetite sensations

    Time frame: Repeatedly measured during the metabolic test before and following consumption of the high-fat, high-energy meal.

    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.

  4. Energy expenditure and fuel oxidation

    Time frame: Repeatedly measured during the metabolic test before and following consumption of the high-fat, high-energy meal.

    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.

  5. Circulating metabolite and hormonal concentrations

    Time frame: Repeatedly measured during the metabolic test before and following consumption of the high-fat, high-energy meal.

    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.

Sponsors and collaborators

Lead sponsor

Jose Galgani

Other

Collaborators

  • Agencia Nacional de Investigación y Desarrollo

Registry information

Official study title

Metabolic Flexibility, Eating Behavior and Adipose Tissue Expandability: Role of This Triad in the Propensity to Human Obesity

Acronym: PROB I

Important dates

Study start
2023
Primary completion
2026
Study completion
2026
First posted
Jun 26, 2026
Registry last updated
Jun 26, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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