Leptin, a hormonally-influenced regulator of appetite, may help explain the greater prevalence of eating disorders in females compared to males. Testosterone reduces leptin levels, and leptin is high in female foetuses when brain organisational effects are likely to be important. The relationship between a negative proxy for prenatal testosterone (ratio of 2nd and 4th digit length'2D:4D) and eating psychopathology were investigated in an unselected sample of women (N=122). Digit ratio (2D:4D) was determined from photocopies of the hand, and eating attitudes and behaviours using the Stirling Eating Disorder Scales (SEDS) and the Eating Disorder Inventory-2 (EDI-2). Independent of BMI, 2D:4D correlated positively with Anorexic Dietary Cognition, Anorexic Dietary Behaviour, Perceived External Control, Low Assertiveness, Low Self-Esteem and Overall pathology on the SEDS. Similar positive associations occurred on the EDI-2 for Drive for Thinness, Bulimia, Body Dissatisfaction and Ineffectiveness, although were not independent of BMI. As predicted all relationships occurred for the right hand. Low prenatal testosterone (high 2D:4D) may allow foetal leptin to rise affecting brain organisation with subsequent increased vulnerability to eating psychopathology.
Quinton, S., Caswell, N., & Manning, J. T. (2004). 2nd to 4th digit ratio (2D: 4D) and eating psychopathology in an unselected sample of women. Appetite, 43(1), 117-117. https://doi.org/10.1016/j.appet.2004.04.001