From the BI article, it sounds like Fisher found it to be a bit extreme, but obviously as a contracted actor in an upcoming movie, she wasn't going to explicitly say so. She most definitely wouldn't be saying if she were doing illegal drugs to maintain that weight:

"I’m in a business where the only thing that matters is weight and appearance. That is so messed up. They might as well say get younger, because that’s how easy it is."

Keep in mind that she's no stranger to weight loss regimens, something she's probably been used to through her peak acting days. In fact, she was Jenny Craig's spokesperson in 2011 and claimed to have lost 50 pounds at that time. The 35 pounds for TFA was either in addition to that, or a swinging of the pendulum since 2011.

http://www.nydailynews.com/entertainment/movies/carrie-fishe...

It depends how much time she had to lose 35 pounds for TFA. If she was complaining that much about it publicly around the time of the movie, it doesn't sound like it was the sustainable kind of weight dropping, at any age. The logic that her weight loss regimen may have saved her life seems counterintuitive...TFA was just a few years ago, and since then, she's probably had to keep the regimen up for VIII. If this weight loss helped her, are you suggesting she was at death's door at the age of 55, until having committed to appearing in TFA? I guess it's pointless to argue causality...for all we know, the heart attack was a freak thing unrelated to weight loss or gain.

As a side note, I find astonishing that she says she was asked to lose 10 pounds to get to 95 for the original trilogy. I had to cut roughly that percentage of body weight for wrestling and that wrecked me, even though most of the weight was lost through extreme exercise and forced dehydration.