It's all about the brown fat! Cold showers (or any cold exposure) both activate it and increase the total amount you have. My body temp is about a degree higher than it used to be, though.

The skin on my torso can produce an incredible amount of heat (people comment on it a lot...), and I will feel it as an all-over 'warmed' sensation. Kind of like how my face feels when I blush. Sometimes it's intense.

It mostly depends on how much I eat. I am pretty sure literally 'burning' a lot of the food I take in... brown fat is cool. :)

I can't withstand hot showers any more, have to intentionally undereat in hot weather, but it's wonderful to feel WARM (even my formerly icy hands and feet) rather than frozen to death when I am holding still or in cool temps. I'm now one of those people running around in a t-shirt when everyone else is wearing sweaters, and a flannel button-down when they're in parkas.

Here is a post on this phenomenon by Richard Nikoley who writes the blog "Free the Animal".

http://freetheanimal.com/2008/09/cold-shower.html

I get this.......... But only after I eat certain foods. If I eat potatoes (and along with a host of other reactions), the top of my abdomen gets really hot, like a burning sensation on my skin and internally that lasts for 10 minutes or so.

Also, I had shingles earlier this year which appeared on my lower back at the base of my spine. If I eat any gluten at all, shortly afterwards I get a burning sensation in the base of my spine and the skin in that area gets really hot. This also happens the day after I've had alcohol too. I'm assuming it's my body's way of telling me that it doesn't like what I'm consuming on occasion - Anybody else experienced this?

I may be looking at everything through a particular lens lately, but since I was just reading about this and you mentioned almonds, it may be a reaction to salicylate. Almonds are very high in salicylates. Chris Masterjohn writes this about the substance:

"Salicylates are aspirin-like chemicals that occur widely in the plant kingdom. They have numerous biological effects, such as interfering with vitamin K metabolism, inhibition of the COX enzyme that produces prostaglandins from arachidonic acid, depressing the synthesis of so-called 'glyconutrients,' and causing the mitochondrial membrane to become leaky, thereby decreasing the production of the cell's major energy molecule, ATP, while increasing the sensation of heat and shutting off the burning of fat."

I am salicylate sensitive but sometimes cheat in the evening so that I can "sleep off" the deleterious reactions to some degree (unwise I'm sure) and find that a number of hours later - usually about 5 to 7 hours later - I feel like I'm burning up and throw off all the blankets. However, this could also be a histamine reaction, or both. I don't know if the sensitivity/decreased excretion itself is the problem or if salicylates can cause this perceived heat sensation alone; not much detail is provided by that quoted text, unfortunately, and I haven't read about this phenomenon elsewhere.