She reminds me of someone I knew that would always eat the smallest, healthiest food option when we went out for dinner, but was the size of a house and claimed it was a metabolic disorder. We all believed it for years, because that's all we'd ever seen. One night after a pool party/BBQ, she polished off a massive bowl of leftover potato salad that had to be at least 3-4kgs of just potatoes, plus the sour cream, bacon, eggs, mayo etc, just picking at it while we sat chatting. Washing it down with vodka and soda water because lower calories, lol, and "salad" is healthy.
I can imagine Tess having a pumpkin spice latte, a tub of that icecream, maybe a pastry/cake, then sitting down with Bowie with pizza for dinner, and still being convinced she hasn't really eaten all day.