I doubt that you will lose anything. Maybe some biceps size but that can easily be solved by doing some additional biceps work if you feel like you are losing some. But honestly, even at complete rest it takes about 2 weeks to lose a significant amount of muscle. With this program you are doing plenty of heavy lifting, so even though you aren't targeting each muscle individually you are still imposing some stimulus do it's doubtful that you will lose anything anywhere. You might feel that a muscle is "flatter", that's because less direct work = less inflammation (which is often mistaken for size).