It's your setup....if the bike is the correct size which I will assume it is since you went to a shop.

Anyone can ride a road bike without this issue regardless of their fitness level if the setup is good. If you are losing weight, your setup will change, just like you might need smaller pants and a differetn size jacket.

You do not need to suffer with this.

I fit bikes. For a long time. It is not uncommon for someone to have this issue out the door with a new bike that has not been properly set up for you.