If your storages are full, there's literally no place for your loot to go when you raid, so you lose it. Here are a few tips for managing that situation:

1. If it's your elixir storage that's full, you can queue expensive troops like PEKKA or drag, freeing up some space in your elixir storage, or go on a clan donation spree.
2. You could choose to forget about the loot and focus on raiding to get trophies.

Alternatively, you could choose to cool off on raiding and drop your town hall outside so someone can attack and give you shield, giving your base time in safety to find something to do with your resources before your next raid.

If your storages are full, there's literally no place for your loot to go when you raid, so you lose it. Here are a few tips for managing that situation:

1. If it's your elixir storage that's full, you can queue expensive troops like PEKKA or drag, freeing up some space in your elixir storage, or go on a clan donation spree.
2. You could choose to forget about the loot and focus on raiding to get trophies.
3. Alternatively, you could choose to cool off on raiding and drop your town hall outside so someone can attack and give you shield, giving your base time in safety to find something to do with your resources before your next raid.