Physiology does seem to play a role in SOME of our food cravings, though not all. Making this an excellent question, Dave.
Research has found that in some cases when we crave salty foods, it may mean we are not getting enough iron, calcium, or potassium. Though instead of going or those salty doritos, opt for a serving of yogurt or string cheese instead.
Chocolate cravings sadly do not hint at any potential nutrient deficiency, however it may simply indicate you are feeling blue which is certainly more common this time of the year. Sweet treats like chocolate help to induce the release of the feel-good neurotransmitter serotonin in our bodies, essentially releasing a mild, temporary antidepressant into our system. Though you do not need to reach for chocolate to reach a mood-lifting high, a healthy douse of exercise or even a romp in the hay with your partner will do the same! If you are actually hungry, a steaming bowl of whole grain oatmeal with raisins will also help to stimulate the absorption of serotonin due to the healthy carbs and vitamin B6.
Though cravings for junk food as you have listed may simply mean that is what your taste-buds, emotions, or mind desire - for reasons outside of physical hunger or nutrient deprivation. If you are simply craving a crunchy snack, try to replace your chips with carrot sticks and hummus. Or if you are jonesing for sweets, aim for a handful of frozen grapes or frozen pureed banana ice-cream with a drizzle of chocolate syrup :)
Cheers to good health!
Jessica Corwin, RD