She's 44 now - she's been pushing carbs, carbs, carbs, and hours of grueling exercise daily for how many years now? I'm assuming since long before ever being on BL - so we're talking decades, right?

Unless she has some kind of super-magical genetics that will not allow her to ever gain weight, and not allow her blood sugar to go out of control on all those carbs, it's going to catch up with her eventually. I give her another 10 years, at the most, before it creeps up on her, and that's only if she's actually able to keep up her current level of physical activity in an aging body. Actually, as she gets older, she's going to need to increase her physical activity, while decreasing her food intake in order to avoid losing muscle and gaining fat on all those carbs, because she's already at the age where it's a battle to avoid muscle loss.

For that matter, if she were to have an accident or illness that kept her invalid or mostly sedentary for months, she'd see just how great CICO actually works - She'd not only lose muscle from inactivity, she'd need to nearly starve herself to death in order to avoid gaining weight, because all those carbs "for energy" would have nowhere to go other than fat cells.