Endocrinological aspects of obesity.

Throughout this review I have emphasized the role that nutrition plays in determining the endocrine abnormalities often found in obesity. There appears to be no consistent thyroid abnormality. Increased cortisol production and metabolism is found in obesity but is reversible with loss of weight. Androgen production is increased in females and can also be reduced with dieting. On the other hand, total serum testosterone is reduced in males, although free serum testosterone is normal in all but those who are severely obese. Various pituitary abnormalities have also been reported; some are reversible but others apparently are not, although extensive follow-up studies are not available to allow a clear distinction to be made between reversible and non-reversible abnormalities. Insulin resistance, a common feature of obesity, is due to receptor and postreceptor defects but again is a reversible phenomenon. Thus there is little to indicate that obesity depends on some underlying endocrine abnormality but much evidence to suggest that the endocrine changes are secondary to the abnormal nutritional state of the patient. This should be remembered when investigating any obese patient for suspected endocrine pathology.