Body composition and susceptibility to type 2 diabetes: an evolutionary perspective

Abstract

1Type 2 diabetes is rapidly increasing in prevalence worldwide, in concert with epidemics of 2 obesity and sedentary behaviour that are themselves tracking economic development. 3Within this broad pattern, susceptibility to diabetes varies substantially in association with 4 ethnicity and nutritional exposures through the life-course. An evolutionary perspective may 5 help understand why humans are so prone to this condition in modern environments, and 6 why this risk is unequally distributed. A simple conceptual model treats diabetes risk as the 7 function of two interacting traits, namely 'metabolic capacity' which promotes glucose 8 homeostasis, and 'metabolic load' which challenges glucose homoeostasis. This conceptual 9 model helps understand how long-term and more recent trends in body composition can 10 then be considered to have shaped variability in diabetes risk. Hominin evolution appears to 11 have continued a broader trend evident in primates, towards lower levels of muscularity. In 12 addition, hominins developed higher levels of body fatness, especially in females in relative 13 terms. These traits most likely evolved as part of a broader reorganisation of human life 14 history traits in response to growing levels of ecological instability, enabling both survival 15 during tough periods and reproduction during bountiful periods. Since the emergence of 16Homo sapiens, populations have diverged in body composition in association with 17 geographical setting and local ecological stresses. These long-term trends in both metabolic 18 capacity and adiposity help explain the overall susceptibility of humans to diabetes in ways 19 that are similar to, and exacerbated by, the effects of nutritional exposures during the life-20 course. 21

Relationship between body mass, lean mass, fat mass, and limb bone cross‐sectional geometry: Implications for estimating body mass and physique from the skeleton

“…Humans have a high proportion of body fat compared to other primates, and to mammals more widely (Pontzer et al, ; Wells, ; Zihlman & Bolter, ). In contrast, skeletal muscle mass (a major constituent of lean mass) is low compared with our closest relatives Pan (Zihlman & Bolter, ), other primates (Muchlinski, Snodgrass, & Terranova, ) and, it has been argued, earlier fossil hominin species (Churchill, ; Churchill, ; Trinkaus, ; Trinkaus et al, ; Wells, ). Within our species, fat and lean masses vary in relation to selective pressures such as climate and disease load (Houghton, ; Wells, ; Wells & Cortina‐Borja, ; Wilberfoss, ), and population variation in body composition is linked to contemporary disease susceptibility (Gysel et al, ; Lear, Kohli, Bondy, Tchernof, & Sniderman, ; Unni et al, ; Wells, ).…”

Influence of obesity, parental history of diabetes, and genes in type 2 diabetes: A case-control study

“…However, the relationship between T2D and obesity may not necessarily be as direct as it appears. For instance, in countries such as China, India, and Japan, in which the prevalence of T2D is high, the prevalence of obesity is relatively low 12,14 . In contrast, in countries such as Australia and the United Kingdom, where the obesity prevalence is high, T2D prevalence is relatively low 15,16 .…”

<p>Body Composition and the Components of Metabolic Syndrome in Type 2 Diabetes: The Roles of Disease Duration and Glycemic Control</p>

“…Indeed, most individuals with T2D are overweight or obese, 11 and T2D patients who are not considered overweight or obese may still have a high percentage of body fat primarily in the abdominal region. [11][12][13] Current studies have indicated that impaired glycemic control and disease duration are the two major contributing factors that affect body composition in individuals with T2D. 14,15 However, data about fat distribution and variations in individuals with T2D are limited and equivocal.…”