You may not give your gut much thought beyond how much your stomach might be rumbling or whether your waistline looks a little bloated over your skinny jeans. But your gut is much more than a depository for your last meal—it’s home to microbes and bacteria that play a crucial role in everything from absorbing nutrients and boosting immunity to reducing inflammation and even balancing your mood.

“Your gut, and the microbiome it contains, is extremely important to your overall health,” explains Raphael Kellman, M.D., founder of the Kellman Center for Integrative and Functional Medicine in New York and author of The Microbiome Diet. The microbiome is a miniature world inside your gastrointestinal tract that makes up 90% of the cells in your body.

“The microbiome plays an important role in immunological functionbrain healthenergy levelsskin, and muscle function,” Kellman says. “When your gut is healthy, the rest of your body is better for it.” Here’s why a healthy gut is good for you, and how you can keep it working at optimal levels.


The bacteria in your gut plays a crucial role in what nutrients your body absorbs from your diet, but they also help determine the amount of calories and energy that enter into your body, says Kellman.

“There is a direct relationship between the microbiome and genetic expression, or how genes are coded for fat deposits,” he says. When you consume highly processed foods and/or those high in sugar, starch, and unhealthy fats, your body typically reacts with high levels of inflammation that can encourage the growth of certain “bad” bacteria in the gut, says Kellman.

This bacteria can overwhelm the “good” bacteria and trigger an overproduction of insulin, which will cue your body to stop burning fat and start storing it.

“When you switch to foods with healthy fats and high-fiber eats that support healthier bacteria, you’ll start to reduce this inflam- mation and reset your metabolism,” he says. A recent study from the University of Iowa found that an unhealthy microbiome in mice can also lead to weight gain and obesity by altering their resting metabolism.


A study published in the journal BioEssays concludes that your microbes can actually influence what you choose to eat. Researchers speculate that microbes manipulate your eating behavior by generating cravings for specific foods—so a host of unhealthy bacteria might have you reaching for that cheeseburger and fries over a simple salad.

That said, eating a healthy diet filled with good-for-your-gut foods can reverse cravings for junk, so you’ll be choosing better options in a relatively short period of time, says Robynne Chutkan, M.D., founder of the Digestive Center for Women in Chevy Chase, MD, and author of The Microbiome Solution


“You have more neurotransmitters in your gut than in the brain,” notes Frank Lipman, M.D., founder of the Eleven-Eleven Wellness Center in New York and author of 10 Reasons You Feel Old and Get Fat. In fact, more than 70% of the feel-good hormone serotonin (which regulates mood, sleep, and memory) is made in the gut. “When your gut is off-balance, your mood changes, and you can become more anxious and depressed,” Lipman says. One recent study published in the journal Brain, Behavior and Immunity found that women who were given a daily probiotic supplement of “good” bacteria for four weeks reported significantly fewer negative thoughts associated with sad moods compared with those who took a placebo.


One of the key functions of the gut, besides its role in digesting food, is to help keep your immune system strong. “More than 80% of your body’s immune system surrounds your gut,” says Lipman. That means that damage to the thin cell wall in the intestines can have a significant effect on your body. “We think that most autoimmune problems people face today actually start in the gut,” he says. And since bacteria, viruses, and other toxins can frequently be found in food, a healthy gut is vital to fighting off infections from foods and the environment.


When you’re not able to fully absorb all the nutrients from your food, you’ll notice a difference in the mirror. “If your gut isn’t functioning well, your hair may be thinner, nails more brittle, and skin more blemished,” says Chutkan. Studies show that more than half of all acne sufferers have issues with gut flora, and the skin condition rosacea has been linked to bacterial imbalance. Research also shows that probiotics can help improve both. “Being healthy on the inside can help you look healthier, too,” she adds.

14 signs your gut is out of whack

The following are symptoms that your microbiome is imbalanced, according to Raphael Kellman, M.D.

  1. Abdominal pain
  2. Allergies
  3. Bloating/gas
  4. Constipation
  5. Diarrhea
  6. Dry skin
  7. Fatigue
  8. Dull or lifeless hair
  9. Headache
  10. Nausea
  11. Low Energy
  12. Low sex drive
  13. Muscle pain
  14. Poor skin color