Research over the past few years has shown how your gut bacteria actually communicates with your brain to cause food cravings for more of the foods that they want to feed on!
When your food intake is high in sugar or refined or processed carbs (breads, cakes, pasta, alcohol etc), the sugar-loving or carb-hungry gut bacteria and yeasts like Candida increase in numbers. They can displace other good bacteria to cause an imbalance, and they secrete chemicals to the cells of your digestive system, which in turn sends signals via the enteric nervous system and vagus nerve (which controls your digestive system) to your brain. This is the gut-brain connection!
When gut microbes are feeling hungry, such as when you change your diet, they effectively tell your brain to cause cravings so that you eat more of what they want to eat! Clever little buggers!
Not all cravings are bad though, as when your body really needs some specific nutrients, your brain will trigger cravings for those nutrients, such as in pregnancy! When eating a balanced nutrition intake, your gut bacteria will also be in balance. But excesses of any foods, good or bad, will also cause a corresponding excess in bacteria which favours those foods.
As a Clinical Nutritionist and Naturopath, I always ask clients whether they are craving any particular foods, as this can give clues as to possible nutrient deficiencies or excesses, and whether their digestive bacteria are in balance or not.
What foods do you crave, or what might you have craved in the past or in pregnancy?!