Coffee and Fasting
I so love coffee and have it nearly every day at the end of my feeding window. Most site admins and IF “pros” will not only tell you coffee is okay, some will tell you that its beneficial citing autophagy abd ketosis–and they are absolutely correct. But, incomplete. Coffee (caffeinated or decaffeinated) induces gastric acid secretion via bitter taste signaling in gastric parietal cells. Studies show caffeine’s effect on gastric acid secretion (GAS) is more complex than has been previously thought. Oral and gastric bitter taste receptors are involved in the regulation of GAS in humans.
Coffee activates gastric acid secretion through part of its effect appears to be mediated by antagonizing adenosine receptors. Bitter substances could excite oral taste cells and mediate their effects through cephalic regulation of gut physiology. Bitter compounds could also act in the gut through induction of gastrin and/or histamine release by GAS-producing parietal cells. All that means is that your body is working on other shit as opposed to burning fat like it should be.
Ah da Ghrelin…. Studies show evidence that activation of bitter taste receptors caused by coffee stimulates ghrelin secretion. Ghrelin is the hunger hormone and is what tells you to eat, makes you hangry, makes you want to break your fast. Modulation of endogenous ghrelin levels may provide novel therapeutic applications for the treatment of weight and gastrointestinal motility disorders. So drinking coffee is supposed to suppress your appetite, but it has the ability to actually make you hungry. Maybe not right away, however it takes about 90 minutes to absorb the coffee, and give you about a 4 hour high, then you will start to notice the hunger.
BUT WAIT there’s more…studies demonstrated that the caffeine accelerates the heart rate without increasing the vascular tonus. This is important considering that the cephalic-phase response during digestion is thought to activate the vagus nerve to enhance digestion. It is demonstrated that bitter receptors in the stomach are involved in the caffeine-induced secretion of gastric acid. This means that gastric acid is floating around in your stomach with no food to absorb it. Think that might be a problem?
References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3033292/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5544304/#r36