Take two wool socks (clean!) you don't mind parting with, one smaller than another if you can preferably. Stretch both out, especially the larger sock. Put the smaller sock inside the larger sock and stuff some cheap, but decent insulating material inbetween (i use Kapok--there was a study done which showed that Kapok was almost as insulating as duckling down per similar weight, but Kapok is very cheap, very hydrophic, and very "green"). Sew up the ends. Then line the inside with heavy duty aluminum foil, shiny side facing in.
Get one of the lighter weight wide mouth stainless steel water bottles and place it in the super insulated sock, stick your longer cooking food in same, boil some water like you normally would, pour in same, and "very lightly" screw on cap (leave some gap so it doesn't pressurize too much), pull rest of sock up an around the top.
Or you could just carry extra fuel, which would weigh less than the above set up. Also would be useless if you use mostly freeze dried type meals, etc for cooking. I don't, but like to buy whole grain quick cook (10 minute or so) org. brown basmati rice. One of my staples for hiking/camping forays.
I have an alcohol stove and i consider the above decent since i consider fuel for alcohol stoves a wee bit expensive, despite that i cut the typical stuff with some 91% rubbing alcohol. The above does allow you to use less fuel for longer cooking stuff like the rice i mentioned.
Theoretically, you could pull out the foil and wear it on a particularly cold foot whilst sleeping too ; )