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.
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,