I have been feeding raw for 20 years
just a few remarks from my end , nothing scientific just observation

1) my main source is chicken fat , I use a lil salmon oil , some yoghurt once in a while
2) dogs on meat tend to be leaner , they have more inner fat so they may look thinner
3) I feed twice a day since the last 6 years they tend to keep weight better

one thing I also changed is that I noticed its better to switch up meat like trhow a fish head or some other stuff trough their weekly diet

hope this helps