I've been 6 weeks out and feel like I've lost a bit of muscle in my chest and shoulders but it could be psychological.

I've heard of ppl losing gains within a few weeks, maybe anecdotal heresay.

How long does it take you guys to notice a difference in your body on breaks from the gym?

depends on how I eat, how much regular exercise I am getting (sitting on the computer all day on the weekends can fuck your shit up)

few weeks depending on diet

I lose strength real fast because I don't do much by way of strength stuff outside of the gym and my eating habits are shit.

I will lose gains within weeks of being away, but I think a lot of the losses are due to dietary deficiency

I notice within a few weeks, but it comes back fast (body composition that is)

This post was edited by boxboxbox on Feb 8 2015 11:03pm

Don't lose motivation, it comes back within the first 2 weeks, and you'll be making gains again.

3 days

If I don't go to the gym for 3-4 days I feel like shit and start to see (myself) changes -- probably all in my head

You won't lose significant muscle mass within a week or even close to that; however, a good diet is prevalent in preventing your body from using muscle tissue for fuel. As for fat gain, that is solely dependent on your diet.

Here's an idea for you: I have been out of the gym for 3-4 months due a big change in my sleep/work schedule. Working full time from 11pm - 10am just sucks the life out of you. Lost all motivation to lift etc. Finally get back in the gym and the biggest factors I noticed are: 1. I gained about 15 pounds of fat...I sat in a chair all day. Then came home and slept and went to school. Expected. You hold a shit ton of water when you don't lift, especially in area like your mid section. 2. More than you lose strength / muscle mass you lose your CNS tolerance. I went from banging 25 - 30 sets a day of heavy training, while in a deficit without thinking twice to hitting 10 sets per muscle group and having the shakes like you have parkinson's. Sucks. However, I don't feel as if I lost much muscle mass tbh. The strength is still there... I just shake terribly bad when I start working above 75% of my 1rm.

Tl;dr: Before you lose strength/ muscle mass, you'll lose CNS tolerance to lifting. Fat gain depends on your diet and to some extent so does your muscle loss.

detraining can be postponed for a month or two with a good diet