Gut Bacteria May Affect Body Weight

Bacteria growing in a Petri dish
Bacteria growing in a Petri dish. Wladimir Bulgar/Science Photo Library/Getty Images

Several new lines of research are now linking gut bacteria to obesity. Scientists are finding that the microbes that call the human gut their home may play a role in body weight, metabolism, and even cholesterol.

What Are Gut Bacteria?

The human gut is home to millions of microorganisms, collectively referred to as “gut flora” or “gut microbiota,” that coexist with us, helping us to digest our food, and perhaps even playing a role in keeping down inflammation, preventing heart disease and maintaining gastrointestinal health.

Thus, researchers are discovering that the composition of a person’s gut flora—the different kinds of gut bacteria and their relative concentrations in each person’s gut—may play a role in that person’s susceptibility to chronic diseases like obesity, diabetes, and heart disease. The many roles that may be played by gut bacteria constitute an area of active ongoing research.

Gut Bacteria and Weight: Two-Way Connection

Recent research has uncovered associations between gut bacteria and body mass index (BMI), which is often used as a surrogate measure of body fat. In a study of 893 people in the Netherlands, scientists identified 34 different types of bacteria that contributed to differences in BMI, and concluded that 4.6% of the differences in body fat (BMI) could be traced to the influences of gut bacteria.

It seems that the connection may go both ways. Ms. Patricia I. Ojeda, Howard Hughes Medical Institute Medical Fellow at the University of Chicago, has reviewed this topic in depth, and found that “there has been convincing evidence linking high-fat, obesogenic [obesity-causing] diets to specific alterations in gut microbiota.

In other words, the macronutrients of the diet can directly change the microbes in your intestine.”

Ms. Ojeda went on to say, “People should be aware that anything you ingest—from fruits to burgers to antibiotics—will alter the bacteria in your gut and therefore alter the way your body processes food.”

Gut Bacteria and Metabolism

According to Ms. Ojeda, the bacteria in our gut play a role in our metabolism, partly by regulating energy extraction from our diet. Gut bacteria can regulate the breakdown of food, including how our bodies process carbohydrates, simple sugars, and dietary fats.

Gut bacteria have also been linked to intestinal hormones which regulate appetite and how quickly or slowly food moves through the gut.

Promising Field of Research

This field of research is an exciting one in many areas, especially in the area of obesity and overweight, because what scientists are finding out about the various impacts of gut bacteria on important metabolic processes may lead to breakthroughs in the treatment and prevention of obesity.

According to Ms. Ojeda, “The data have been very exciting in this field of science and continue to show more links between our bodies and the bacteria inside of them. Within the next few years, science will definitely offer some innovative advancements in health by directly altering the microbiota of the intestine.”


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