Thanksgiving week— for those who celebrate, is a week of indulgence, gluttony (in a good way?), and feasting. Fasting has become a wellness trend, with promises of clearer thinking, better metabolism, and longer life. But allow me to somber your mood for a minute, because at a time when we have so much, it’s always the best time to give to those who have not. Hunger — not individuals who have the privilege of intermittent fasting— is an enormous problem in the world, from famine in the war-torn Middle East to right here at home, where children dependent on SNAP might be going hungry. I hate it.
But what happens to your gut when you stop eating for a while—or when your body enters a true state of starvation? The gastrointestinal (GI) tract is a living, breathing system that depends on constant nourishment to function properly. When that input stops, your gut doesn’t simply “pause”—it changes.
Your intestines are powered by rhythmic muscle contractions known as peristalsis, which keep food and waste moving. When you stop eating, these contractions slow, and the entire digestive system becomes more sluggish. People who fast for long periods often notice constipation, bloating, or cramping once they start eating again. Even the stomach slows its emptying rate, which is why a small meal can feel so filling after a fast.
Your gut bacteria are just as dependent on food as you are. They thrive on dietary fibers, resistant starches, and plant compounds that you eat. During fasting or starvation, those nutrients vanish, and the microbial ecosystem shifts. Some beneficial species decrease, while others—especially those that feed on mucus from your gut lining—begin to dominate. Over time, this can reduce microbial diversity and weaken the gut barrier. Fortunately, in short-term fasting, these changes usually reverse once you resume eating a fiber-rich diet. For those experiencing long-term hunger, gut dysbiosis can lead to long-term poor health outcomes.
The cells that line your intestines renew themselves constantly, but that process requires a steady supply of nutrients and energy. Without food, regeneration slows, and the gut lining may thin, creating tiny gaps between cells. This can allow inflammatory molecules and bacteria to slip through, potentially triggering low-grade inflammation—sometimes referred to as a “leaky gut.”
When there’s no food to digest, the body reduces production of bile, stomach acid, and pancreatic enzymes. While this is a normal energy-saving response, it can make digestion more difficult when eating resumes. This is why breaking a fast too quickly can cause nausea, cramping, or diarrhea. A gentle reintroduction of food—especially easy-to-digest options like soups or steamed vegetables—helps the system restart smoothly.
Hunger hormones like ghrelin rise during early fasting, triggering that familiar growl in your stomach. But with prolonged fasting, the body adapts—ghrelin levels fall, and hunger temporarily fades. Meanwhile, hormones such as GLP-1 and insulin shift to help maintain energy balance. These hormonal changes partly explain why intermittent fasting can affect metabolism, appetite, and even weight regulation.
Short, structured fasts under medical guidance can support metabolic health for some people. But prolonged starvation stresses the GI tract, slowing movement, changing the microbiome, and weakening the intestinal barrier. Your gut is designed to be fed—and it functions best when nourished consistently with fiber, protein, and hydration.
Did you know that 1 out of every 10 senior citizens has food scarcity? If you’re thinking about it, considering donating to World Central Kitchen, which has provided chef-quality meals for those who need it since COVID.
If you’re thinking about fasting for health reasons, do it thoughtfully and talk with your doctor—especially if you already struggle with constipation, reflux, or other digestive issues. Your gut will thank you for a balanced approach.
And if you are amongst those lucky enough to share food with your family and friends this holiday season, stay grateful and stay curious, and happy holidays, from my family to yours. Thanks for being on this journey with me.
Until next time, that’s just the way the anus wrinkles.