From this question:
"...we crave junk because we need to feed the processes that are involved in inflammation...which is actually a protective mechanism for healing from these "fight or flight" bursts. The junk food, of course, causes more gut problems and eventually can start causing autoimmune problems as well.**"
- Dr Heather
It seems that specific cravings for sugar and other pro-inflammatory junk foods might exist for more of a reason than simply food reward. To a body under stress, such inflammatory substances may be perceived as beneficial to maintaining the inflammation.
I think it certainly could be involved, but for me, it's when I get bored that the M&Ms and chips in the machine downstairs start whispering sweet nothings (literally!) in my ear.
Assuming that our current knowledge is at least partially correct, "Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process."
Directly from Wikipedia.com,
"Inflammation can be classified as either acute or chronic. Acute inflammation is the initial response of the body to harmful stimuli and is achieved by the increased movement of plasma and leukocytes (especially granulocytes ) from the blood into the injured tissues. A cascade of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells within the injured tissue. Prolonged inflammation, known as chronic inflammation, leads to a progressive shift in the type of cells present at the site of inflammation and is characterized by simultaneous destruction and healing of the tissue from the inflammatory process."
So, what we may have here is another example of formerly adaptive biological processes (acute inflammation due to illness/injury) becoming maladaptive due to a novel environment ( chronic stress, impaired sleep, malnutrition, etc.)
I would say, however, that no one "needs" junk food any more than someone "needs" cocaine, alcohol, etc.
Craving carbohydrates may have been adaptive in the past, when all we would have had access to was roots, shoots, and fruits, but this also assumed that we either "fought" or "flew".
Getting yelled at by your boss, you kids having a melt-down and the grocery store, sitting in a traffic jam, etc. creates the same chemical cascade with none of the physical release of activity.
Stopping at McDonald's for a McFlurry may be the modern equivalent of pounding wild berries after outrunning a mountain lion, but we also have the capacity to use our intellect to override our instincts (at least some of the time).
I think so! The more I read about cortisol going up and down at irregular intervals due to stress, the more revealing the vicious cycle is. Eating too much or too few carbs causes physiological stress. Really, though, nothing seems better than a nice big 'ol bowl of ice cream after a stressful day!
Even if stress didn't cause you to crave carbs, the increased cortisol levels will hurt your metabolism and sleep (which, is essential for the fat metabolizing process!)
Physiological stress, in my opinion, is more annoying than emotional stress. I love seeing myself lose weight, and I can easy manage my work so I'm not stressed on that end. It is ironic because stressful diets can lead to weight gain or lead to a condition which can result in weight gain or increased difficulty losing weight.
The word "the" in your question stops me cold. You didn't ask, Is stress "a" cause, as in: one of many possible, potential, causes.
I admit, the search for single, sole, all-explanatory "cause" (of Everything, or just Anything) continues to exert a certain pull on me as well.
But probably "junk food cravings" is not some singular thing, thus not caused by any singular thing.
Damn. Complexity is just so much more ... sobering.
If I'm having a day where I didn't get enough sleep it oftens makes me a bit edgy. On days when I'm a bit edgy and in need of a nap, my appetite SOARS. (I don't have these days very often, but when I do it's crazy how it impacts my appetite.)
In years past, I'd eat an entire box of Fruity Pebbles. Now I simply eat a lot more meat with meals.