Tip: Immunize Yourself Against Fat Gain

Consume a little bit of this substance every day to prevent fat gain or lose fat. Here's the science.

Gut Bacteria and Body Fat

It's becoming increasingly clear that the little bacteria-beasties in our gut play a huge role not only in our health, but also in the way we think. One could almost say that we're all just puppets on their bacterial strings.

Our resident bacteria affect how we balance levels of sugar in our blood, how we respond to hormones that make us feel hungry, and even how we store fat.

Luckily, we're not entirely at their beck and call and we can take back control of how we process food by manipulating the numbers of specific varieties of these bacteria. In doing so, we can affect how much body fat we carry.

Recent studies have given this idea more credence. Specifically, we can stop additional fat from accumulating and also make dieting much, much more effective simply by reducing the populations of one type of bacterium and increasing the numbers of another.

This fat loss/fat prevention protocol appears to be as easy as eating a little bit of a particular kind of underpublicized dietary fiber every day.

What Scientists Have Discovered

Danish researchers have found that the ratios of two gut bacteria can make or break the difference in the effectiveness of dieting. They analyzed the levels of Prevotella and Bacteroides bacteria in the feces of 62 overweight people.

They then randomly assigned the obese subjects to either a low-fat diet high in fiber, fruits, vegetables, and whole grains, or one that was more in line with the average Dane.

After 26 weeks, those on the high-fiber diet had fewer Bacteroides bacteria and higher numbers of Prevotella bacteria. As a result, they lost an average of 10.9 pounds of fat, which was 3.5 pounds more than those on the diet that maintained a high number of Bacteroides bacteria.

Gut Bacteria

Some Perspective, Courtesy of a Different Study

Another study, this one conducted by Canadian researchers on 42 obese children, also centered on changing bacterial numbers. This one, however, involved raising numbers of Bifidobacterium instead of Prevotella, but again at the expense of Bacteroides.

Instead of putting them on a weight loss diet, they just fed 22 test subjects one specific prebiotic (food for bacteria) dietary fiber – inulin. Subjects initially received 4 grams a day, but after two weeks the amount was raised to 8 grams per day. A control group of 20 obese children was given 3.3 grams of maltodextrin a day (an amount equivalent in calories to 8 grams of inulin).

The inulin group saw a big drop in the number of Bacteroides bacteria, which stopped the growth of additional body fat. The maltodextrin group, however, continued to add layers of fat. Note the distinction between the Danish study and the Canadian study, though.

The Danish study altered the ratio of bacterium in conjunction with a weight loss diet. The Canadian study, however, just altered bacterial levels, i.e., no specific diet was prescribed. Instead, they just gave them inulin fiber and let the overweight kids continue eating as they always had.

The Danish dieters, as a result of altering bacterial ratios, lost fat, while the Canadian children merely stopped adding layers of fat. The Canadian children, in fact, had in a way been immunized against further fat gain, while the Danish subjects had used a combination of diet and prebiotic fiber to, in a sense, "cure" themselves of fat.

What To Do With This Info

Even if you're not dieting, but especially if you are, it'd be a good idea to foster a beneficial ratio of Prevotella or Bifidobacterium to Bacteroides. There are a couple of ways to do this. You could do it through diet and ingest inulin-rich foods like asparagus, leeks, and onions, etc., but no sane person really wants to do that.

Alternately, you could go dig out the Ezekiel bread from the back of your breadbox and eat two to four slices a day, which is a lot more palatable. Ezekiel bread is a type of low glycemic index bread made from sprouted grains and one slice contains 80 calories, 4 grams of complete protein, and 3 grams of fiber, much of it inulin.

Eating four slices of it wouldn't in itself approximate the 8 grams the Canadian children were given in the study, but it should do the trick when combined with any respectable amount of whole fruits and vegetables you get through the course of a normal day (many of which contain at least a little inulin).

Lastly, there are inexpensive pure inulin supplements available that you can add to protein shakes, mix into recipes, or drink on its own combined with juice or water. Start with 2-3 grams a day and build up to 8 or more.


  1. Hjorth, MF, et al, "Pre-treatment microbial Prevotella-to-Bacteroides ratio, determines body fat loss success during a 6-month randomized controlled diet intervention." International Journal of Obesity, 8 September, 2017.
  2. Nicolucci, A. et al, "Prebiotics Reduce Body Fat and Alter Intestinal Microbiota in Children Who Are Overweight or With Obesity." Gastroenterology, September, 2017, Volume 153, Issue 3, Pages 711–722.