I'm a bit surprised that this article doesn't deal with the increasing amount of science behind neurological food reward mechanisms. The tl;dr is that our junk food (and much mass-produced food in grocery stores) has been tailored for a kind of hyper-palatability that mutes the effectiveness of our normal satiety mechanisms. So in the article's context the "nudge" is up against an evolving attack by industrial food against very low-level neurological mechanisms.

I don't have a good "lay" source for this field, but I'd recommend digging into Stephen Guyenet's blog[1], that is if you're up for wading through an academic's professional musings. He's a neurobiologist and obesity researcher, and as such the blog provides his perspectives on ongoing work (his and others') in this field. Warning: DO NOT go here expecting any specific answers, and be able to deal with a fair bit of hypothesizing (i.e. untested, maybe totally wrong) both on Guyenet's part and via the work he reviews. You'll only really get a sense of how this field is going as you pick up enough context of ongoing work. IMO, the most interesting self-contained posts that go by are the significant negative results, where robust work comes to light that just crushes an existing hypothesis.

[1] http://wholehealthsource.blogspot.com/