Peter at the Hyperlipid BLOG has an interesting analysis of an interesting paper on fat storage in mice (On phosphorylating AKT within visceral fat). The study he looks at is (Narita T, Kobayashi M, Itakura K, Itagawa R, Kabaya R, Sudo Y, Okita N, Higami Y. Differential response to caloric restriction of retroperitoneal, epididymal, and subcutaneous adipose tissue depots in rats. Exp Gerontol. 2018 Apr;104:127-137). The study looked at ad lib feeding of mice and the storage of fat in three White Adipose Tissues (WAT) depots in rats: retroperitoneal (rWAT), epididymal (eWAT) and subcutaneous (sWAT).
Peter’s interest is in fat storage based on insulin levels. The study compared ad libitum to calorie restricted eating in the mice. Peter concentrated on the ad libitum eating of the mice (not being all that interested in calorie restricted diets). Peter points out that it takes insulin to store fat in subcutaneous tissues but very little insulin to store fat in visceral fat. The study put it this way:
In all WAT depots, CR markedly upregulated the expression of proteins involved in FA biosynthesis in fed rats. In visceral WAT (rWAT and eWAT), hormone-sensitive lipase (lipolytic form) phosphorylation was increased by CR under fed conditions, and decreased by CR under fasted conditions. Conversely, in sWAT, hormone-sensitive lipase phosphorylation was increased by CR under fasted conditions. CR enhanced the effect of feeding on AKT activity in sWAT (indicative of a positive effect on insulin sensitivity) but not in rWAT or eWAT. These data suggest that CR improves lipid metabolism in an insulin signaling-dependent manner in sWAT only.
As Peter puts it:
This looks very much like one of the intrinsic differences between subcutaneous adipocytes and visceral adipocytes is that visceral adipocytes maintain insulin signalling at much lower levels of plasma insulin than do subcutaneous adipocytes. You have to store calories which arrive without insulin somewhere. Looks like this is the place!
I’m still of the opinion that visceral fat is what matters the most in reversal of Type 2 Diabetes. The Low Carb diet gets insulin levels low which reduces fat in general. See this article (A Grand Unified Theory of Polyunsaturated Fatty Acid Misbehaviour in Inflammatory Disease).
This article is actionable as well (Fatty liver and its treatment).