This may be of interest to those of you who are diabetic or pre-diabetic — an increasingly large portion of the population. As a starting point, I would recommend reading “The Obesity Code” and “The Diabetes Code” by Dr Jason Fung. These books address the linkages between diabetes, insulin secretion, fasting, and macronutrients in the diet - carbohydrates in particular. I highly recommend this material if you are interested in dietary measures to improve diabetes.
Beyond this is the puzzle of food cravings - carbohydrate cravings in particular. “I have a sweet tooth,” “I binge on comfort foods,” “I crave bread.” This is a common phenomenon and has not been fully explained.
A few hypotheses: hypoglycemia from insulin dysregulation causes carb cravings; dopamine reward for sudden surge of blood sugar; gut microbiome causes chemical messengers to brain, that are interpreted as craving for carbs.
There are other hypotheses, but these three cover a significant amount of the territory. I wish to address the third - that gut microbiome may be signalling the brain to eat carbs.
This is an appealing hypothesis which explains the observed lessening of carb cravings that comes after abstinence, as well as the rekindling of carb cravings that arise when they are eaten. Hypothetically, carb-craving microorganisms are repopulated when they are fed, and release a stronger chemical signal to the brain, asking for more carbs. When they are starved of carbohydrates, carb-craving microorganisms depopulate, and the signal that they send to the brain is weaker.
The research literature on this question is all over the map, meanwhile. I am just beginning to read it. For now, I will start with the longstanding observation that diabetics are prone to fungal infections of the skin. Presumably, something about the diabetic body creates this predisposition. One simple hypothesis is that fungi thrive in high-sugar environments. The body tissues of diabetics have a higher proportion of sugar.
Presumably, it is reasonable to assume that diabetics also have a higher population of fungi in their guts, and that their skin infections are the result of migration of gut fungi to the skin.
We can further hypothesize that gut fungi are carb-dependent, and signal the brain for carbs in order to further their growth.
This hypothesis can be sketched out thus:
This model suggests new approaches to diabetes. Is the model accurate? What confirmatory data is out there?