Can Antibiotic Residues in Non-Organic Food Make You Gain Weight?

By Ari LeVaux
It's been known since the 1950s that feeding low doses of antibiotics to livestock increases their weight gain. The practice, dubbed subtherapeutic antibiotic therapy (STAT), lowers feed costs while increasing meat production. Nearly 80 percent of the antibiotics purchased in the United States are used for this purpose. The practice is suspected of facilitating evolution of antibiotic-resistant "superbugs" like MSRA, which infects both pigs and people and is known to be especially common at pig factory farms. Meanwhile, it's finally coming to light that antibiotics can do to people what they do to livestock: make us fat.

Data has supported this hypothesis since a 1955 study in which antibiotics and placebos were given to three groups of Navy recruits. The placebo group showed the least weight gain, significantly lagging behind the two groups given different antibiotics. In general, the rates of obesity have risen with antibiotic use since their discovery, but as they say in science, correlation does not equal causation. Recent research, however, is turning up evidence that this correlation might not be a coincidence. The basic idea is that bacteria alter the body's microbial communities, also known as the microbiome, and this disruption changes the way our bodies metabolize and store food.

A study published August 27 in Nature looked at how antibiotics impact the microbial balance in mice, and how this might affect weight-gain patterns. One group of mice was exposed to STAT, the other not. Bacteria from the guts of mice from these two groups was compared, and the researchers found antibiotics altered the microbial ecology in the guts of the exposed mice, changing their metabolism.

Can getting enough sleep help you lose weight?

Is shedding weight harder while stressed or missing sleep?

People getting too little or too much sleep were less likely to lose weight in a six month study of 472 obese people.

Their report in the International Journal of Obesity showed that lower stress levels also predicted greater weight loss.

A UK sleep expert said people need to "eat less, move more and sleep well".

Approximately a quarter of adults in the UK are thought to be clinically obese, which means they have a Body Mass Index greater than 30.

Nearly 500 obese patients were recruited for the first part of a clinical trial by the Kaiser Permanente Center for Health Research in the US.

For six months they had to eat 500 fewer calories per day, exercise most days and attend group sessions.

Weight loss

The authors report that "sleep time predicted success in the weight loss programme".

People with lower stress levels at the start also lost more weight.

The researchers added: "These results suggest that early evaluation of sleep and stress levels in long-term weight management studies could potentially identify which participants might benefit from additional counselling."

Dr Neil Stanley, from the British Sleep Society, said the sleep community had been aware of this for a while, but was glad that obesity experts were taking notice.

"We've always had the eat less move more mantra. But there is a growing body of evidence that we also need to sleep well", he said.

"It's also true that if you're stressed, then you're less likely to behave, you'll sit at home feeling sorry for yourself, probably eating a chocolate bar."

Dr David Haslam, chair of the National Obesity Forum, said: "It's a great idea to find predictors of who will respond to therapy, if this is a genuine one."