There's hospitalist fellowships you can do after IM too. Mind you, they're mostly focused on QI and other administrative stuff, but they still exist.
I'll disagree with both of you a bit. I think that there's a lot more heterogeneity in the focus on inpatient adult medicine in FM programs than IM programs.
In IM, we
must do at least 12 months of inpatient medicine (including ICU) over the course of the 3 years - and I don't know any program that is anywhere close to the minimum. Most of us do closer to the maximum of 21 months (12 months must be outpatient including EM, and 3 months is average for vacation over 3 years - out of 36 months total).
In FM, there's a lot of other things that need to be fit in - more extensive clinic requirements, Ob requirements, peds requirements, etc. So while
some programs get them enough adult inpatient experience that they are competent in the hospital, not
all programs do. If I recall correctly, the FM program at the institution where I did residency averaged 7 or 8 months total inpatient adult medicine over their 3 years - including the ICU month they did on "our" service. Other programs in other parts of the country - particularly at hospitals without a concurrent IM residency - do significantly more. Hence why many urban and suburban hospitals will only consider BE/BC internists for their hospitalist groups - it's just easier than trying to vet someone who may or may not have adequate training.
@MedicineZ0Z says "tons" of FM programs have extremely good inpatient training and I have no idea what proportion is what, but certainly some do - and many don't. Just like some FM programs put out people who have the confidence to continue with Ob and many don't - even though they all theoretically meet their minimum numbers.