Adding columns upped my RAM usage significantly

I have a Google Cloud Platform MySQL 2nd Gen 5.7 instance with two databases, one for testing and one for production. There are about 20 or so tables. One of the tables accounts for 99% of the storage. I added 8 columns to the largest table (it already has ~150 columns) of the testing db. 6 of the new columns are Integer and 2 of them are Boolean (or more accurately, TinyInt). No indexes of any kind added. Below is a snapshot of the metrics from the migration operation. You can clearly see CPU and Storage peaks for each of the 8 columns. Weird part is, RAM usage goes up an stays up. Any insight on what I may have forgotten to do? The columns did not have any data populated to them, all are Null for each row so far