Not a whole finger, just like a 1cm or so. Make sure the sphincter is still clean when you relax your butt hole.
This applies to on the loo or in the shower and DEFINITELY with a wet wipe before a wax.
Weight gain is more often than not a symptom but is treated as a cause. When people focus on weightloss it creates an unhealthy mental state and the goal of weightloss often comes at the sacrifice of health. Having a goal weight is one of the most unhealthy things you can do for yourself and the health benefits you may experience are outweighed by the negative impact.
Edit for clarification: I'm arguing that doing anything FOR the purpose of losing weight is unhealthy. I am not saying losing weight is unhealthy itself. I am not even saying being obese is healthy. I'm saying if you are going to the gym TO lose weight, if you are changing your diet TO lose weight, if you are taking medication TO lose weight it is an unhealthy action. The goal to lose weight is what is unhealthy. Moving for mobility, mental health and gut health is healthy, weightloss is often a by product but should never be the goal.