Just because people can consume pure lard, and gain a tonne of weight, it doesnt mean theyre not malnutritioned. It also doesnt mean they dont experience hunger.
If you take a step back and consider the primary question that needs to be answered is it
a) What weight is a measure of hunger/poverty - people must be over x weight irrespective if health and were good.
b) What food availability us a measure of hunger/poverty - people must have reasonable acess to a basic set of nutritional inputs and were good.
You seem to be following a - people are fat, so hunger doesnt exist
When it would be equally truthful, with a different conclusion to say - people are feeling hunger and experiencing malnutrition. When they can eat, what they can afford causes increased body mass without fulfilling their nutritional requirements. They also continue to feel hungry.
Treat food similar to medicine, the good benefit is the target, but there are also side effects. Cheaper food has a worse profile - fewer (not none) benefits, and higher side-effects.
Theres also more complexity to this - poverty isnt just $. Education, transportation, time, exhaustion, health. Many intersections and impacts that paint a persons life.