From the article:
Santosa’s research compared fat storage in pre- and post-menopausal women. The 23 women who participated in the study were in the same age range, and had similar Body Mass Indices and body fat composition. These similarities allowed Santosa to isolate the effects of estrogen on fat absorption and storage.
She and Jensen were able to examine the activity of certain enzymes and proteins that regulate fat storage in post-menopausal women’s abdomens and thighs. By considering these factors together rather than in isolation, the researchers determined conclusively that the overall fat storage “machinery” is more active in post-menopausal women. In other words, these cells now store more fat than they did before menopause.
In addition, post-menopausal women burned less fat than their pre-menopausal colleagues. These changes mean that their cells are not only storing more fat, but are also less willing to part with it. This combination is a recipe for rapid weight gain. “Taken together, these changes in bodily processes may be more than a little surprising – and upsetting – for women who previously had little trouble managing their weight,” comments Santosa.
Though the increased cellular activity revealed by this study was not specific to the abdominal region, more fat stored overall means more abdominal fat.
From the publication:
We found that meal FA [fatty acid] storage in subcutaneous fat was greater in postmenopausal than in premenopausal women. This difference was especially evident in the femoral depot, where meal FA [fatty acid] storage in postmenopausal women was double that of premenopausal women.
[…]
The increase in fat storage stems from somewhat greater LPL [lipoprotein lipase] activity and significantly greater content of adipocyte FA [fatty acid] storage factors. It is possible that the upregulation in proteins associated with FA [fatty acid] storage capacity in postmenopausal women contributes to the decrease in postprandial total fat oxidation. Whether the differences in FA [fatty acid] storage between premenopausal and postmenopausal women are attributable to the effects of estrogen or the combination of estrogen, progesterone, and other factors, such as changing insulin concentrations, remains to be elucidated.