Your approach to this situation is where your problem lies.
You are raising and reraising AK preflop b/c of your equity edge against the rest of the field. You will often have the best hand preflop and need to exploit that edge. Build a pot when you have an equity edge is a good thing. This is more money for you to win!
The bigger problem I see is in your post flop approach. Just b/c you put in 3-4 bets preflop and a bet or so on the flop does not mean you have to finish to the river because it is "just one bet." You need to look at the dynamics of the board and player(s) you are up against. This is where you are losing your money. You cannot continue calling down when your AK does not hit. This is not to say that calling down is not the correct play at times, but you need to be selective.
Check out this post:
QTip's recent post on calling down with AK or folding on the Turn
This has some interesting discussion in it. There are probably better examples out there as you are concerned with the big multiway hands. Do a search.
Anyhow, I think your adjustment needs to be post flop and your reading.
This whole "It is better to be defensive" and "I'll lose less money" mentality are surely not the answer. If you aren't playing AK hard, what are you playing? Don't turn into a weak-tight fish [img]/images/graemlins/smile.gif[/img] Stay on the good side!