She is tough, but very lean. Not that much body fat, so low reserves.

As for fasting. I fast sometimes, but I would not try fasting on a long hike in mountains like Pyrenees. Probably not even Tatras.

Depending on what's in the skin cream, it might not be an unreasonable thing to do. They often contain not much more than plant fats and stablilizers. Probably the perfume will make it taste foul, but it won't kill you.