Let me confidently assure you that inflammation in the hypothalamus is a dominant feature of obesity, and obesity is currently one of the top diagnosed medical problems in America. This stuff isn't hypothetical, but well accepted within the clinical research field for metabolic disorders.
Please don't recommend laymen avoid reading articles like this. That's rather senseless. While this stuff hasn't become standard in medical school curricula yet, it definitely will be some day, particularly when we are more confident in interventions that prevent hypothalamic gliosis.
EDIT: also, don't discount hypothalamic inflammation based on what you know about encephalitis. Some parts of the hypothalamus (the arcuate nucleus, in particular) are highly susceptible to inflammation because they are surrounded by a characteristically porous part of the blood brain barrier (behind the hypophyseal portal system). This allows bulky blood-born protein hormones (like leptin and insulin) to make it into the sensory neurons.
Indeed this part of the brain doesn't become red and painful, but something more relevant happens. Microglia surround the neurons responsible for appetite suppression and kill them off, which permanently changes the body fat setpoint that the brain strongly defends. There is definitely a profound and sometimes irreversible loss of function here, and that's the current focus in research. Hopefully some day we will find ways to drive repair of these circuits.