Between 1978 and 1983, I read three (?) books in a series which described a future world in change. (The books I read were in Danish, translated from English.) The change depended on the location of the suns, and one of the phases or events was referred to in Danish as FAT DEATH. There were probably three phases, each of which triggered different pressures on populations that had to learn to adapt. There might have been different races in each of the phases.
The three books - as I remember - had a colorful front, one was mostly green and another purple. Maybe I was looking at planet from above? Not sure. I think the books were already ten-plus years old in 1982.
It was not The Faded Sun trilogy by C. J. Cherryh.