Study uses questions like: “How often in the past 12 months would you say you were worried or stressed about having enough money to buy nutritious meals?”

By design, this study causes obese people who eat up their food supplies to be more likely to be captured by the study than their less consumptive counterparts, even with equal amount of available food.

I would expect someone who shovels enough food in their mouth to be obese to be the kind of person to spend more than needed for meals (or to end the meal with less spare reserve food), causing them to stress about their overspending. It's not much surprise an obese person shoveling down food is more worried about overspending than the skinny person not shoveling down their hatch until they are the size of Oklahoma. Eating 4000 calories of even the cheapest food like rice and beans costs more than eating 2000 calories worth rice and beans; of course the blimp-sized person eating the 4000 calories of rice and beans is going to stress more about the cost than the person eating 2000 calories of rice and beans.

Put another way, it makes sense to me a food insecure person might say "I will buy 4000 calories worth of rice and beans instead of 2000 calories worth of rice and beans because I am food insecure, then I will save the difference in case food is inaccessible later." An obese person will then eat all 4000 calories and stress about being out of money, and become "food insecure" via this study by answering they're worried. Whereas the skinny person is not gonna stress as much, because they still have 2000 calories worth of rice and beans after their meal is done, and thus be less likely to be classified "food insecure" by the question of this study. That is, the study is designed to capture the obese person as being more food insecure even when they have same food availability of the less obese person.