Multiple symmetric lipomatosis: a paradigm of metabolically innocent obesity? Response to Haap et al.

E xcessive fat storage (obesity) is associated with insulin resistance and type 2 diabetes (1). Paradoxically, inability to store fat (lipodystrophy) is also associated with insulin resistance (2). In both obesity and lipodystrophy, the adipocyte’s storage capacity is exceeded and lipids accumulate in liver, muscle, and -cells. Hypothetically, if adipose tissue had an intrinsic propensity to proliferate, rather than passively respond to energy excess, calories should be extracted from the circulation and the system should become (or remain) insulin sensitive. Such a process would be particularly effective if it occurred preferentially in subcutaneous adipose tissue, which, metabolically, is the least harmful site (3).