I learned that when matter is transformed into energy in a fusion reaction that the gravity associated with the matter that has transformed into energy is not lost. Electromagnetic energy has gravity and is not just a property of mass. I was given this answer on a question about black holes...
When matter is transformed into light energy within a star, the gravity associated with the matter is now associated with the light's energy. As space expands, the redshift is dilluting the light's energy and reducing the gravity associated with that energy. Would the energy dillution further...
There is a lot of great astrophysics now available for casual readers and viewers like me, and it is fun to speculate and cross reference ideas. The episode of the Universe (History Channel) on black holes describes that at some point matter that gets too close is stretched, rotated, and heated...