Short layoffs mostly cost you neural sharpness and glycogen, not muscle, and both bounce back within one to three sessions.
After one to three weeks off you lose very little actual muscle. The strength dip is mostly neural, your nervous system loses practice grooving heavy bar paths, plus depleted muscle glycogen makes you look and feel flatter. Come back at 70 to 80 percent of your old loads for a session or two and you will usually be back to baseline within two weeks.
Real muscle loss (atrophy) does not meaningfully start until roughly three weeks of no training. A one or two week break mostly dulls motor coordination and intramuscular tension, so the weight feels heavier even though the tissue is intact.
Muscles store carbohydrate as glycogen, and each gram pulls water in. Time off with less eating drains those stores, so you look flatter and lighter, and endurance drops on higher rep sets. A few days of normal eating and training refills it.
You keep muscle memory from previously built nuclei in the fibers, so regaining lost strength is far faster than the first time. Most lifters returning from a two to three week break are back to full loads within one to two weeks.
Short layoffs mostly cost you neural sharpness and glycogen, not muscle, and both bounce back within one to three sessions.
