It’s always nice when weight loss recommendations involve eating more of something rather than less of everything. A new study provides welcome information that people eating a diet high in soluble fiber—found in foods such as oatmeal, beans, nuts, apples, lentils and blueberries—are less likely to gain weight than those who lack the substance, which is technically a type of carbohydrate the body can’t digest.

The study found that consuming lots of high-fat, low-fiber food can alter the gut microbiome, which leads to a state of constant low-grade inflammation. On the other hand, eating soluble fiber provides a more hospitable environment for the gut microbiota, allowing the tiny bugs (healthy bacteria) to perform their jobs so vital to the body’s health: helping to digest food, producing vitamins, fighting microorganisms and maintaining general intestinal function.

So how could something that, ahem, moves right through our system without being absorbed be so helpful to our metabolism? Scientists think that soluble fiber decreases inflammation in the gut—and it’s inflammation that can lead to weight gain. 


One key point to glean from this study is that soluble—not insoluble—fiber played the hero. Insoluble fiber does not mix with water and simply adds mass to the bowels, helping food to pass through the stomach and intestines. Soluble fiber dissolves in water, and according to the Harvard School of Public Health, it can help lower blood glucose levels as well as cholesterol. 

So excuse me while I go make a batch of oatmeal-blueberry-almond cookies (my microbiome is having a mad craving). 



  1. Science Daily: Diet lacking soluble fiber promotes weight gain, mouse study suggests
  2. Harvard School of Public Health