Gutbliss - Dr. Robynne Chutkan


Fermented Foods For Weight Loss


Fermented foods are projected to be one of the leading weight loss trends throughout 2019, but they’ve actually been around for a long time. The fermentation process is one of the oldest examples of food preservation, and fermented foods have been a foundational staple of the human diet throughout history. 

Unfortunately our modern ways of eating – processed, high fat, high salt, and high sugar foods – have taken the place of more traditional and healthful ways of eating. Fermented foods are now one of the least consumed foods in the U.S., despite the fact that they are one of the most important for gut health, specifically for your gut microbiome. Studies show that daily and long-term consumption of fermented foods can lead to improved weight loss. 

What are fermented foods & why are they beneficial for weight loss?

The fermentation process transforms the food into a substance that’s rich in microbes and compounds beneficial for health. Specifically, because of their high prebiotic (food for microbes) and probiotic (actual microbes) content, fermented foods feed the beneficial bacteria in our guts, helping to increase the amount of good microbes, and crowding out harmful ones. These “good” bacteria help digest food, fight off pathogens, and balance the gut microbiome –an important factor in weight management. Fermented foods are also high in fiber, which creates a lasting feeling of fullness, resulting in lower calorie consumption. Studies show that adding more fiber into your diet alone can result in the same amount of weight loss as extreme dieting. 

Like adding fiber into the diet, studies show that incorporating probiotic bacteria from fermented foods and supplements, can result in more weight loss in overweight participants. Based on recent studies, these probiotics may prevent fat accumulation by suppressing lipid (or fat) absorption from the food you eat and promoting fat excretion through the feces. A 2015 study overfed participants a high fat diet and gave one group probiotics and the control group a placebo; the probiotic group gained 50% less body fat than the placebo group. When regularly consumed, both kimchi and sauerkraut have been associated with lower obesity rates in rodents and human subjects

While these studies are compelling, if you’re consuming probiotic bacteria primarily for weight loss (or other health reasons) it’s important to consume them from food as opposed to a probiotic supplement. Some probiotic strains have actually shown to promote weight gain, so sticking to the real stuff in whole food form will ensure you’re getting high quality, beneficial microbes that work synergistically with other beneficial food compounds and fibers to promote health. 

The Case of Microbial Imbalance

Studies also show that imbalances in the gut microbiome – specifically a high Firmicutes to Bacteroidetes ratio and low diversity – can cause our bodies to extract more calories from the food we eat, therefore making weight gain more likely. Our gut bacteria play a key role in breaking down food particles and some bacteria are better at it than others, enabling more calories to be digested (instead of excreted in the feces) and harbored by the body. Two studies have illustrated that alterations in gut bacteria can lead to vastly different body compositions. When bacteria from two mice strains – one lean and one obese – were transplanted to germ-free mice, those who received the bacteria from the obese mice became obese and those who received bacteria from the lean mice stayed lean. The same is true when bacteria were transplanted from the guts of two identical twins – one lean and one obese – into germ-free mice; the obese twin’s bacteria made that recipient mouse fat, while the bacteria from the lean twin did not. 

While we are still unsure as to exactly how our gut microbiome dictates our weight, these scientific studies tell us that the beneficial bacteria in our guts, as well as the probiotic-rich foods we consume, play a leading role in maintaining a healthy body weight and in one’s ability to lose weight. 

But how do we make sure our microbiome is one that promotes a healthy weight? There are many ways, but the best way is to consume high fiber, prebiotic- and probiotic-rich foods like… fermented foods! 

A Differentiation Worth Noting: Pickled vs. Fermented

We often lump together pickled and fermented foods and assume they are one and the same. But in fact, pickling and fermenting are quite different. Pickling preserves food using an acidic substance like vinegar, and these foods when found in grocery stores usually undergo extreme heat to preserve and sterilize, destroying any beneficial microbes. Fermenting differs in that the acidic substance is created by the food itself – microorganisms (bacteria and yeast) convert carbohydrates into alcohols or organic acids. These foods are rich in beneficial bacteria and are the good stuff we want to consume. 

Fermented and pickled foods fall into three categories: pickled (pickles and other jarred vegetables that are shelf stable, found in grocery stores), fermented (including alcoholic beverages and kombucha), and fermented and pickled (which includes kimchi, sauerkraut, and other ferments that must be refrigerated) – these are the number one choice when it comes to promoting weight loss and a balanced microbiome. 


Now that you know what a fermented food is and why it’s so important for microbial balance and weight management, it’s time to get fermenting! As you embark on your fermented food journey, we encourage you to prepare your fermented foods at home. Most unrefrigerated store bought options that are jarred or canned undergo a pasteurization process that destroys beneficial microbes and compounds. In addition, store bought ferments are often higher in sodium and sugars than homemade ones. Fermenting your own food can be a fun and fairly simple process. Try these introductory recipes to get you started and commit to consuming one serving of fermented foods each day: Kimchi, Gingered Carrots, and Coconut Milk Kefir.

share this story:

Still hungry? Here’s more


Dr Robynne Chutkan
Dr. Chutkan's Newsletter
Read the latest news and research from Dr. Chutkan’s blog. From the most up to date science on the microbiome, to the best in gut-derived wellness – we are your complete guide to gut health! Sign-up now and receive free access to our 7-Day Microbiome Reboot Course.