Phenotypic Characteristics of Superlean Individuals Including Gut Microbiome

Study on the Phenotype and Gut Microbiome Composition of Healthy Superlean Individuals (BMI < 18.5)

The goal of this observational study is to build on our previous work to further characterise the phenotype of superlean individuals (BMI < 18.5) when compared to normal BMI people (BMI 21.5 to 25). This will include characterising the body composition, food intake behaviour, circulating hormone levels, genetics and characteristics of the gut microbiota. The investigators expect to recruit up to 200 healthy superlean and control volunteers respectively,

Study Overview

• Status: Completed
• Conditions: Health Behavior; Thinness
• Intervention / Treatment: Other: Observation without intervention

Detailed Description

The focus of this work is to characterise the phenotype and genotype of individuals who have low BMI ( < 18.5) but are otherwise healthy and do not have eating disorders. The investigators term this group 'superlean' individuals. The study is observational and the investigators aim to establish a healthy superlean cohort,and use the combined metagenomic and metabolomic multi-omics analysis techniques, combined with imaging and physiological measurements, to focus on the correlation between gut microbiota characteristics and metabolism in superlean population. The investigators expect to recruit up to 200 healthy superlean and control volunteers (BMI 21.5 to 25) respectively, to explore the microbiota characteristics and differences between control and healthy superlean populations by measuring the basic physical indicators and metabolic parameters. This will include analyzing the postprandial hormonal changes, appetite differences, and changes in the gut microbiome and serum metabolome in the two groups of volunteers, establishing the relationship between the gut microbiota and the metabolite and metabolic phenotypes of the body, and exploring the gut microbiota.

• Study Type: Observational
• Enrollment (Actual): 104

Contacts and Locations

Study Locations

• China
  • Shenzhen, China
    • Shenzhen Institute of Advanced Technology,

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 25 years to 40 years (Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Participants are healthy, with no metabolic disorder, 25 - 40 years old

Description

Inclusion Criteria:

• Control group (21.5≤ BMI<25), Superlean group (BMI≤18.5)
• Age between 25-40 years old

Exclusion Criteria:

• Having metabolic diseases or eating disorders
• Recent weight loss due to various disease causes
• Being treated for weight loss
• Having an infectious disease
• Pregnant and lactating women
• People with blood sickness, pathological hypo- or hypertension
• People suffering from claustrophobia
• No metal implants in the body
• Use of antibiotics, probiotics, oral laxatives, etc. within 8 weeks

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Control; 21.5≤BMI<25, age between 25-40 years old, 200subjects.	Other: Observation without intervention; Observation of food intake, body composition, microbiota, genetics, metabolic rate, metabolomics.
Superlean; BMI≤18.5, age between 25-40 years old, 200 subjects.	Other: Observation without intervention; Observation of food intake, body composition, microbiota, genetics, metabolic rate, metabolomics.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Weight	Volunteers will be asked to fast for 10 hours and measured fasting weight.	Through study completion, an average of 2 years, will be measured on arrival.
Height	Height will be measured by seca 217 stable stadiometer.	Through study completion, an average of 2 years, will be measured on arrival.
Waist circumferences	Waist circumferences will be measured using a whole body laser scanner.	Through study completion, an average of 2 years, will be measured on arrival.
Hip circumferences	Hip circumferences will be measured using a whole body laser scanner.	Through study completion, an average of 2 years, will be measured on arrival.
Bone mineral density	Bone mineral density will be measured by Dual Energy X-ray Absorptiometry (Horizon Wi).	Through study completion, an average of 2 years, will be measured on arrival.
Fat mass	Fat mass will be measured by Magnetic Resonance Imaging (Shanghai united imaging, uMR 790 ).	Through study completion, an average of 2 years, will be measured on arrival.
Fat free mass	Fat free mass will be measured by Bioimpedance Analysis (Tanita, MC-980).	Through study completion, an average of 2 years, will be measured on arrival.
Blood pressure	Systolic and diastolic blood pressure will be measured using an Omron sphygmomanometer.	Through study completion, an average of 2 years, will be measured on arrival.
Glucose	Fasting and post-prandial glucose after a standard meal will be recorded by the continuous glucose monitoring system.	Through study completion, an average of 2 years, will be recorded for a consecutive of 7 days.
Body temperature	Body temperature will be measured before and after feeding using a thermal imaging camera.	Through study completion, an average of 2 years, will be measured before and after feeding.
Resting energy expenditure	The measurement of resting energy expenditure will be performed using indirect calorimetry.	Through study completion, an average of 2 years, will be measured on arrival.
Physical activity	Physical activity of the participants will be recorded using GT3X monitor for a consecutive of 7 days.	Through study completion, an average of 2 years, will be recorded for a consecutive of 7 days.
Body shape	Body shape will be measured using a whole body laser scanner.	Through study completion, an average of 2 years, will be measured on arrival.
Energy intake	Response on standard feeding table, the food consumption will be recorded continuously by balances underneath each food dish. The total energy intake will be calculated in KJ (kilojoule).	Through study completion, an average of 2 years, will be measured on arrival.
Circulating hormones	Levels of circulating hormones (including leptin, insulin, ghrelin etc) will be measured when fasted and after a standard intervention meal. Levels of circulating hormones in the serum will be measured by ELISA (Bio Tek, Synergy4) in mmol/L.	Through study completion, an average of 2 years, will be measured after standard intervention meal.
Microbiome	Abundance of gut microbiome will be from Metagenomic profiling of feces by Illumina.	Through study completion, an average of 2 years, will be measured after samples collected.
Metabolites	Abundance of metabolites will be from metabolomic profiling of serum and feces by LC-MS (liquid chromatography-mass spectrometry).	Through study completion, an average of 2 years, will be measured after samples collected.
Genetics	Polymorphic variation will be assessed in a panel of SNPs (single nucleotide polymorphism) previously linked to body composition and physical activity using a Mass array sequencer.	Through study completion, an average of 2 years, will be measured after samples collected.

Collaborators and Investigators

• Sponsor: Shenzhen Institutes of Advanced Technology ,Chinese Academy of Sciences

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2023
• Primary Completion (Actual): May 1, 2025
• Study Completion (Actual): May 1, 2025

Study Registration Dates

• First Submitted: February 17, 2023
• First Submitted That Met QC Criteria: March 27, 2023
• First Posted (Actual): April 7, 2023

Study Record Updates

• Last Update Posted (Actual): January 21, 2026
• Last Update Submitted That Met QC Criteria: January 19, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Microbiome; body composition; Metabolism; food intake; food preference; Superlean
• Additional Relevant MeSH Terms: Body Weight; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Feeding Behavior; Thinness; Health Behavior; Food Preferences; Investigative Techniques; Methods; Observation
• Other Study ID Numbers: SIAT-IRB-221115-H0628

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No