If that's all Kai is eating in the one meal, then it looks about the perfect size for someone over about 6 months out from WLS. If there's a massive serving of mashed potatoes on the part of the plate I can't see, then there shouldn't be. She'd still be able to eat it, because it is what is termed a slider food, however with the amount of carbs in mashed potatoes she might just as well be having full sugar candies and cookies.
As a general guide after a few months (once all the swelling from the stapleline has gone down), the average WLS patient should be able to comfortably consume around 3oz of meat plus about half a cup of cooked vegetables. By 12 months out they should still only be at that 3-4oz of meat but by now able to eat a whole cup of cooked veg. Kai looks to be quite short, so she'd be looking at needing to lose another 100lb before they'd approve her skin removal. Most plastic surgeons also require around a year of maintaining the weightloss before they'll do skin removal as well. So Kai is a long way off that.