A real German life hack to stay warm for lighter packing weight is naturally the kidney warmer! These have seen service since the Kaiser's reign; these warmers are Bundeswehr surplus from the Cold War era, so that's a lot of service years in between. Today they do make waist warmers, but they're NOTHING compared to an actual proper army article.

Ahh, this waist warmer is a beautifully countoured piece of comfortable wool/cotton flannel. Its ends are meant to be ran through each other and the package is finished with the tie-strings. No breakage-prone zippers or hook-n-loop stuff!

If you are unfamiliar with this glorious article, it's meant to be used with the wide face on the backside where the kidneys are. When you get off duty and go to town, turn it around to get that extra bit of wealthy girth to attract the ladies.

Although these do have long traditions in the Germanic cultures, we weren't able to find any photographical evidence of their use in Kaiser's Germany, Hitler's Germany nor either of the divided Germanies. Therefore we must settle for vivid imagery of freezing Landsers waiting in frozen foxholes for the Red Army to swipe over them. At least they saved in pack weight and die with warm kidneys, we guess!

Genuine Bundeswehr surplus

These are used for a bit, stored for a long time, intact and usable for a long time to come. Get one while these are available!