According to this 73.6% of adults over 20 in the US are classified as overweight or obese, so 78% of Covid hospitalizations being overweight or obese is not at all surprising.

This means that overweight and obese people are roughly 5.8% more likely to be hospitalized with Covid than people who are not overweight or obese. Hardly the slam dunk you're implying it is. (Of course I'm potentially making a mistake by excluding under 20s without knowing if the covid hospitalization statistic you're mentioning also excludes them, but taking that into account is too much research/math for today - what percentage of the US pop is < 20 years old?).

(As a side note, that article is awful (and I assume the source of your mistake) - it seems to imply that "obese" and "overweight or obese" are the same thing, except the former is 41.9% of the population and the latter is 73.6%. Not sure if intentional misuse of statistics, or just incompetence).