Adipose morphology and metabolic disease

Adipose morphology is defined as the number and size distribution of adipocytes (fat cells) within adipose tissue. Adipose tissue with fewer but larger adipocytes is said to have a ‘hypertrophic’ morphology, whereas adipose with many adipocytes of a smaller size is said to have a ‘hyperplastic’ morphology. Hypertrophic adipose morphology is positively associated with insulin resistance, diabetes and cardiovascular disease. By contrast, hyperplastic morphology is associated with improved metabolic parameters. These phenotypic associations suggest that adipose morphology influences risk of cardiometabolic disease. Intriguingly, monozygotic twin studies have determined that adipose morphology is in part determined genetically. Therefore, identifying the genetic regulation of adipose morphology may help us to predict, prevent and ameliorate insulin resistance and associated metabolic diseases. Here, we review the current literature regarding adipose morphology in relation to: (1) metabolic and medical implications; (2) the methods used to assess adipose morphology; and (3) transcriptional differences between morphologies. We further highlight three mechanisms that have been hypothesized to promote adipocyte hypertrophy and thus to regulate adipose morphology.