It is nothing, unless you provide exertion context. And even then fitness and fatness are not mutually exclusive.
However,
Walk outside. Do you see hulks or pot bellies ?
You both have good points. Realistically the morbidity and mortality in this outbreak have correlates closely analogous to almost every other infectious disease, with the single exception that children are often symptom free although there is not yet clear evidence that I can find to suggest they are not carriers of the virus, just that are usually free of COVID-19.
There are more and more studies appearing about morbidity and mortality, mostly seeming to reinforce the generalizations above. Lancet has published some carefully stated ones using Wuhan data as the base:
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30566-3/fulltext
Otherwise there are a group of data that seem to fit well with morbidity and mortality data used by parts fo the health insurance industry. Other things remaining equal, age itself correlates well with susceptibility precisely because age correlates well with many diseases, thus tending to conflate age with disease. That is fallacious, even though the human immune system does become less effective with age, so it is easy to assume that age is the determining factor when it mostly is not.
The two overarching behavioral characteristics that always correlate with disease susceptibility are smoking and obesity. Always! Smoking never has an exception, but obesity is itself an analogue for poor cardiovascular condition.
After those two issues it becomes statistically very simple and logical. The following categories of disease preexisting (NOT in history, but now existing) tend to have around 75% higher presence when almost any viral infection is acquired:
Cardiovascular
Diabetes
Kidney
Pulmonary
Hepatitis B
Cancer
If two or more such diseases are present the morbidity and mortality both tend to rise by about 250%.
There are many sources for such data, including those of COVID-19 such as those of Lancet. Every virus has distinct difference in communicability, gestation periods and both morbidity and mortality. The relative susceptibility, though, is nearly always along the lines I show above. The primary differences tend to be the prevalence of childhood susceptibility (thus the 'childhood disease' category) as well as the normal practice to require annual flu vaccinations for very young and very old, while being less rigid for others.
If there is one reason for acutely urgent reaction worldwide this time it is that old people are living longer than ever before while chronic diseases that once killed quickly now have continuing treatments, notably kidney, cardiovascular, diabetes and pulmonary. That very success causes increased risks for every new communicable disease.
That seems to be a significant factor in Italy, China, Korea, the US and elsewhere. That also suggests the catastrophic consequences that may result from inadequate prevention and provision of every category of ICU support as well as all categories of pulmonary disease treatment.
Given all of that, perhaps among the most promising short term treatment is the use of purified serum from fully recovered patients, to speed antibody development. That is hardly scalable. It is itself a risk because existing testing may tend to produce false negatives when viral loads are very low, thus suggesting recovery when it has not yet actually happened.