Karen seemed to always put on a happy and brave face despite the obvious sadness she felt in her life. Dionne Warwick and others seem to imply in comments that everything was back on track for Karen. But I think she must have been very scared about what was ahead of her.
First off, despite the weight gain in the hospital, she must have been terrified of the prospect of gaining any more. Richard has commented that she still picked at her food. There is also the evidence that she was abusing ipecac. So weight gain must have been on her mind. She had the pressure to convey that she was cured but was desperately afraid of gaining weight. If she was eating normally, using ipecac, and still maintaining her 108 weight, I wonder if her metabolism had slowed down requiring the ipecac to stay steady.
She also desperately wanted children. But she was still married (almost divorced) and would have to start the whole process over again of finding a partner. All of her friends were married or in relationships and having children, she must felt anxiety to move forward as well. Today being 32 and unmarried is so common. But back in 1983, there was still a stigma around it. I recall the Mary Tyler Moore show, a #1 hit of the 1970's, was based on the storyline of a women being 30 and god forbid, unmarried. It wasn't that common back then. She had felt that pressure before to get married and have kids and made the unfortunate choice of Tom Burris. So I can't imagine 2 years after her first marriage, for the pressure to have lessened. It must have been on her mind.
Finally, there were career pressures. The Carpenters were not able to score a top 10 hit for 8 years. Nothing seemed to be sticking. This also must have been on her mind. She was ambitious and not the type to sit back and relish past successes.
In retrospect, none of the above was all that serious of a problem in the grand scheme of things. Karen could have take the route of healthy living, focusing more on eating well and exercising. Today, there is the trend of leading women following that strategy. They have amazing bodies but are healthy. Karen was also relatively still young. She had at least another 10 years to have kids. She could have also adopted and been a wonderful mom. Finally, she had already achieved amazing success, enough to sit on her laurels and not worry about it anymore. Money would never be a problem and chart success was already achieved. She could have focsued on charitable work and performing for the fun of it. But unfortunately, she didn't have enough time to see the forest from the trees.