Numerous times weekly, I am contacted by individuals wanting to work with me for weight loss, but who suspect that they first need to treat an underlying digestive issue prior to starting another unsuccessful weight loss attempt. They are convinced, and I believe rightfully so, that their inability to lose weight despite tremendous efforts is stemming from unresolved gut issues. It is quite validating to them when I agree that their hypothesis has validity, as I often see that my weight loss clients with concurrent unresolved digestive issues often do not lose weight until we spend 3 to 4 months fixing up the gut. To quote Dr. Kenneth Brown:

“Gastrointestinal and digestive issues can definitely have a large effect on the way we eat and how our bodies absorb and digest foods, causing us to gain or lose weight. Most digestive problems tend to cause weight loss from poor absorption of food, but there are a few situations in which our intestinal health can contribute to weight gain.”

Below are three common conditions I see that can contribute to a difficulty losing weight:

GERD (Gastro-Esophageal Reflux Disease,) also known as “heartburn”

GERD sufferers tend to experience relief when the stomach contains food, and often experience nausea on an empty stomach. Eating provides temporary relief because both the food being eaten and the saliva from actually chewing that food neutralize acid. The only problem? Once the food’s been digested, the bloating, burning, and nausea symptoms appear even more aggressively because of rebound acid production. But because people want immediate relief, it’s easy to get sucked into a dangerous cycle of overeating that leads to weight gain.

SIBO (Small Intestine Bacterial Overgrowth)

This condition, particularly common in our community, manifests as severe bloating and distension post-meal, with often concurring IBS symptoms such as pain, constipation, or diarrhea. It’s caused by the movement of bacteria upwards from the large intestine into the normally sterile small intestine, where these bacteria then have a field day eating carbs coming in from the stomach, producing uncomfortable gassy byproducts.

SIBO causes weight gain in two ways. Firstly, the bacteria often produce methane gas, which slows down the overall function of the small intestine, allowing the intestinal villi to absorb more calories per bite. In other words, the exact opposite of what you want to happen if you are trying to lose weight. Secondly, SIBO can slow down metabolism and cause insulin and leptin resistance, both of which help regulate hunger and satiety. As a result, you’re likely to crave carbs and probably won’t feel full after eating, even if it’s a fully satisfying meal. I find it helpful in SIBO cases to add to the regimen the probiotic strain lactobacillus gasseri, which research has demonstrated to improve weight loss efforts.


When you’re stopped up, that weighed-down feeling you get may translate into extra pounds on the scale due to the weight of the extra fecal content being stored. But there’s good news: your body isn’t actually absorbing more calories, says Brown, so it’s not true fat storage gain. However, when individuals are constipated, they don’t exactly feel motivated to hit the gym or take a jog. That sluggish feeling accompanying long-term constipation can therefore indirectly lead to actual fat and weight gain due to decreased motivation to exercise.

The good news is that most individuals who resolve their digestive troubles can lose weight, although they need to be patient and work through the gut repair process for a few months first. Amazingly, we now know that the health of the gut and the billions of microbes that reside in it affects not just our long-term health, but our ability to lose and maintain a healthy weight as well.

Tamar Feldman, RDN CDE is a Registered Dietitian/Nutritionist and a Certified Diabetes Educator and is co-founder of the app GI Trak. She maintains a busy virtual practice to an international clientele, specializing in balanced and sustainable weight loss and nutrition therapy for autoimmune and gut issues. She can be reached at 732-364-0064 or through her website: