Seriously, you could pop your MRE food packet into your IBA and it would get… pretty hot, actually. People tried this and they’d keep an MRE packet tucked in their vest for awhile and pull it out when ready. I didn’t try this myself, something about chow heated by my own lava-like sweat in the heat of Iraq just seemed…. wrong.
The heat of the desert in military operations has given rise to some interesting stories– it is said that in World War Two, German (and I heard, British) soldiers in North Africa could literally fry an egg on the exposed metal of their tanks if they wished: Panzer Fried Eggs
Of course, with MREs, you always have to contend with the ingredients of the MRE itself:
I don’t know who did this PhotoShop but… well played, sir, well played.