Right. My limited understanding of this--and keep in mind I'm just regurgitating what I've read from those who support this way of eating--is that novo lipogenesis is a very inefficient process, and that you'd have to overeat a significant amount of _simple_ sugars for basically months to store even just a pound of body fat. I think the idea with this eating plan is, if you are keeping fat low, you will fill up on starchy foods long before you will eat enough calories/carbs to cause novo lipogenesis.
Definitely open to hearing counterpoints here... trying to learn about this stuff is overwhelming because it seems like you can find material, even scholarly research, to support any nutrition plan.
"de novo lipogenesis" in Latin literally means: "generating fat from new" - funny how knowing some Latin from school is always a bit helpful in understanding or remembering things like this one.
Dietary fat is rarely stored. It is mostly either burnt (metabolic upregulation) or excreted.
Excess glucose in the blood, however, is stored as fat, through a process known as de novo lipogenesis.