I feel like that doesn't capture my goals. I am looking to be able to offer play that is not all-alpha-all-the-time. So I want diversity. I'd like to be able to sometimes offer conserve-your-power-carefully play.
So it is about diversity in play, not punishing players.
For me this problem is solved in the following ways:
1) Always give hints to your players that there is more to the world than the current encounter. NPCs and monsters have allies. There are bigger and meaner things stalking the adventure location. If an NPC or monster escapes the fight they will seek revenge or to recapture whatever was lost. The PCs should rarely feel comfortable just reasting in a place that is not a safe haven.
2) Limit the effectiveness of rests or expand the time. I allow 3 short rests per day, each takes twice as long as the last...15 min, 30 min, 1 hour. Long rests in the dungeon reset this but only count as a short rest...long rests require a completely safe haven or very well stocked and established camp amd take 24 hours.
4) Before they decide to rest help them understand that the NPCs will get a "turn" in the larger game. Rooms will restock. Wounded will heal. Reinforcements might arrive. PC allies mught be attacked, etc. Give an ingame consequence. Your adventures should not feel like an old school CRPG where the monsters are just waiting for the PCs to come kill them.
4) Talk to your players. If they are going nova every encounter there is a reason. I advise my players that I want them to use their kewl powers and their consumable items. They will tend to use a power or two to establish dominance in a fight then will start to conserve because they understand that they don't know how safe they really are. By 3rd level they should have made some allies...and a few enemies.
To me, the 5MWD problem is not solved only with rules. It requires the DM to present a game world that is dangerous enough that the players feel they have to conserve resources and press on even when they are low. It also requires the players to stick to the social contract that their PCs have motivations (sometimes unspoken by the DM) to finish the adventure...they want to get back to soft bed and warm food, to lives they left behind, or they want to have time for other things.