One of the most prevalent medical issues confronting the American public is obesity, a condition that has become much more common over the last several decades. As of 2010, about 36% of American adults over the age of 20 qualified as obese. In comparison, about 15% of adults were obese in the year 1980. When the topic of American’s weight problem comes up, fattening and sugary foods usually get the blame. While eating such items do inevitably lead to bigger waistlines, new evidence in recent years has found that the presence (or lack thereof) of bacteria in the stomach may also play a role.
The Role of Antibiotics
The introduction of antibiotics in the 1940s revolutionized the way doctors treated bacterial medications. Common ailments such as pneumonia, which at one time killed and hospitalized hundreds of thousands of people annually, were now much less of a threat. Unfortunately, it appears that antibiotics have become an overused medical tool; in 2012, the World Health Organization warned about excessive antibiotic use, noting that such medications could lose their effective if this trend is not reversed.
What does any of this have to do with obesity? Well, as their name indicates, antibiotics work by killing off harmful bacteria within the body. However, they are not able to do this without collateral damage. Bacteria aren’t inherently bad; in fact, the body needs a fair amount of bacteria in order to properly digest food. In addition, these “good” bacteria also assist your immune system, and help prevent harmful bacteria from multiplying within the digestive tract.
All of the combined bacteria, viruses and single-cell organisms known as eukaryotes form the body’s microbiome. Of course, this means that the microbiome includes good bacteria within the stomach and intestine. Recent studies have noted that antibiotics may have unintended consequences on the patient’s health, killing off the microbiome’s helpful digestive bacteria. In turn, this appears to affect the way the body utilizes and stores food.
Bulking up Mice, Livestock…and Humans?
One of these studies appeared in the August 22, 2012 issue of the scientific journal Nature. This particular report, authored by researchers from New York University, examined the effects of regular doses of antibiotics on two groups of mice. One group of mice was given small doses of antibiotics on a routine basis; the second was given no antibiotics whatsoever. The mice who were received antibiotics put on much more body fat than the non-medicated mice, even though both groups were placed on the same diet. Furthermore, the fecal matter of the mice given antibiotic drugs had fewer calories, indicating that the antibiotics had caused these subjects to absorb more of their meals.
Mice are hardly the only animal in which such a connection has been noticed. For decades, farmers have treated cows, pigs and other animals with antibiotics as a way to fatten them up, allowing them to yield additional product from their livestock. Likewise, some research has found that antibiotics may cause young children to develop weight problems.
This was the conclusion reached by yet another 2012 study produced by New York University, which reviewed the medical records of over 11,000 babies born in Britain during the 1990s. According to this report, infants who were given antibiotics during the first six months of life had an elevated risk of being overweight by age three. Specifically, these children were 22 percent more likely to be carrying extra weight. It warrants mentioning that this relationship diminished greatly after the six month mark; children treated with antibiotics at a later point did not exhibit significant gains in weight.
The Effects of Good Bacteria
All of this research brings up an interesting question – can the addition of “good” bacteria possibly help keep your waistline thin? A team of scientists from Washington University in St. Louis sought to answer just that question, transmitting human gut bacteria into rodents and observing the subsequent effects. For their sources of human germs, the research team used four sets of twins, with each pair consisting of one lean and one obese sibling. The team chose this approach because obese and thin people do not possess the same combinations of gut bacteria. In order to eliminate any possible genetic explanation for the subjects’ weight differences, the group of eight subjects included a set of identical twins, meaning that they possessed the exact same DNA.
What the Washington University team found was that the germs appeared to influence the mice’s weight over the course of the study. Though both sets of mice were fed the same diet, those given bacteria from the thin humans gained much less weight. In order to further test this possible link, the researchers took advantage of a highly unpleasant dietary habit among mice – mice are coprophagic creatures, meaning that they will eat each other’s droppings.
Both sets of mice were placed in a single cage, where through this process the intestinal bacteria of the thin mice was transferred to their fatter counterparts. The results of this experiment came as a surprise to the research team; the fat mice lost weight and developed a faster metabolism, whereas the weight and metabolisms of the thin mice were not affected. Nonetheless, diet still played a decisive role in the experiment; the mice only saw improvements in weight and metabolism if they were fed a low-fat, high-fiber diet.
Antibiotics certainly serve an important medical purpose, and continue to be highly useful for people suffering from potent bacterial diseases. Despite their benefits, overuse of antibiotics has become a major worldwide health issue, and multiple studies suggest that this problem could be contributing to the world’s growing waistline. With obesity continuing to be a large problem (pardon the pun), it is likely that this issue will continue to receive much attention in the future.