When you’re trying to lose weight, it’s a good idea to look at all possibilities. One of the newer ideas out there is the connection between probiotics and weight loss. Probiotics are beneficial bacteria – in this case, those found in the intestines – that are integral to good health. Although scientists haven’t determined exactly how probiotics affect weight, there is some pretty good evidence that such is the case.

What’s the Connection Between Probiotics and Weight Loss?

The digestive system contains trillions of bacteria (known as the gut microbiome), which aid in the process of digestion. In particular, probiotics help break down fiber into fatty acids. Some of these bacteria also synthesize vitamin K – which is necessary for proper blood clotting and immune system function – and vitamin B12, which affects neurological function.

What Research Says

Researchers first began to explore the link between probiotics and weight loss in mice. They discovered that when gut bacteria from obese mice were transplanted into lean mice, the lean mice rapidly began to gain weight. Research in humans confirmed that people who were obese had a different gut microbiome than those who were of normal weight.

Further research indicated that two classes of bacteria called Firmicutes and Bacteriodetes are important in energy balance. The term “energy balance” refers to the relationship between calories eaten in food and calories expended in activity. When caloric intake and expenditure are roughly the same, your weight is stable. However, this is a much more complex issue than simply calories in, calories out. 

Considerable additional research will be necessary to unravel the exact relationship between the gut microbiome and body weight. However, research does indicate that the gut microbiome may affect inflammation, which has been implicated in a number of diseases – obesity and heart disease among them.

Why Bacteria may Help With Weight Loss

woman making a heart sign in front of her abdomen

When it comes to probiotics and weight loss, it’s important to recognize that there are multiple species of bacteria within each class. For example, Lactobacillus and Bifidobacterium are two of the probiotics people most commonly take as supplements. Both of these are in the Firmicutes class. Some of the individual strains that have been identified within that group include L. gasseri SBT 2055, L. rhamnosus ATCC 53103, L. rhamnosus ATCC 53102, L. plantarum and Bifidobacterium lactis Bb12, all of which seem to have an anti-obesity effect. However, L. fermentum and L. ingluviei seem to promote weight gain, at least in animal studies.

The research can be confusing, as different studies have variable or conflicting results. In some cases, the research is funded by supplement manufacturers, which may influence the findings. In one study, for example, 20 men aged between 18 and 30 ate an additional 1,000 calories a day for four weeks and took either a probiotic supplement or a placebo. Those who took the real probiotic supplement seemed to be protected to some extent from gaining weight. The differences were small, however, as was the study, which was funded by a supplement manufacturer.

A Japanese study looked specifically at Lactobacillus gasseri. Thirty healthy study participants drank either fermented milk with the addition of Lactobacillus gasseri or fermented milk without the bacteria. The two were otherwise identical and the taste was the same. Those who drank the milk with added bacteria excreted more fat in their bowel movements, while those who drank the regular milk showed no change in fat excretion. This indicated the bacteria helped promote fat excretion rather than the fat being digested and absorbed, which means a decreased caloric intake.

How to Use Probiotics For Weight Loss

bowl of kimchi

Probiotics are available in two forms – supplements and fermented foods. Dozens of types of probiotic supplements can be found on the shelf and they often contain different strains of beneficial bacteria as well as different proportions of the various bacteria. The odds are high, based on the research so far, that it is the overall balance of bacteria within the gut that affect health, inflammation and weight gain or loss, rather than a specific single bacteria.

One Chinese study (review of multiple other studies called a meta-analysis) found that taking multiple strains of probiotics for at least eight weeks seemed to be the most effective in promoting weight loss. If you choose to take a probiotic supplement, follow the manufacturer’s instructions.

If you prefer to get your probiotics from food, your choices include products like yogurt, kefir and fermented vegetables like sauerkraut and kimchi. Many of these can be made at home and recipes are readily available online. If you choose to buy fermented foods, look for the term “active cultures” on the label.

You should discuss the use of either supplements or fermented foods (especially those that are not pasteurized) with your doctor, prior to starting them. This is particularly important if you have a chronic condition like diabetes or an immune system dysfunction.

Disadvantages of Probiotics

There is very little information about the long-term use of probiotic supplements, although fermented foods have been eaten in many cultures for thousands of years. The cost of supplements varies according to the manufacturer, the combinations of beneficial bacteria and the other ingredients in the supplement. Both foods and supplements may need to be refrigerated.

Probiotics and weight loss could be a winning combination. Even if you don’t lose weight, it’s clear that a well-balanced, healthy gut microbiome promotes overall health. However, a healthy diet and exercise also make a big difference. Do let us know if and how did probiotics help you shed the extra pounds.

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