There is studies to suggest that you can maintain your HPTA function on 20mg of anavar for up to 8 weeks with only a slight drop in your LH and FSH.
However, at your age your LH and FSH might be low due to aging, so you might be at risk of it shutting down.
You should have a test base, to ensure you have bio-identical male hormone in your body. Realistically at 48 you should be on medical TRT for lifestyle improvement.
If you are deadset against injecting yourself, you should at a minimum run 12.5mg of enclomiphine to ensure your HPTA remains active.
I would make sure you get bloodwork beforehand to find out what your baseline hormones are.
Anavar will not make you "leaner and stronger". A caloric restriction will make you leaner. Progressive overload will make you stronger.