Children on More Antibiotics Gain Weight Faster

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According to a study published this October in the International Journal of Obesity, children who receive antibiotics are more likely to gain weight than those who don’t.

The study was conducted at the Johns Hopkins Bloomberg School of Public Health, whose lead researcher Brian S. Schwartz, MD, MS says that children who take antibiotics in childhood may have their BMI changed forever and that they may gain weight faster over time.

Schwartz alongside his colleagues assessed the health records from the Geisinger Health System, taking into consideration 163,820 children between the ages of 3 and 18 and the data gathering took place from January 2001 to February 2012, in order to analyze the effects of antibiotics on the weight of children.

The researchers analyzed the use of antibiotics as well as body weight and height for each year for which there were records of receiving antibiotics.

They found that at the age of 15 the children who took antibiotics 7 or more times during their childhood weighed approximately 3 lbs more than those who didn’t take these drugs. There were records of around 30,000 children who received antibiotics 7 times or more, and probably also a considerable number of those who received them but were not registered in the health system.


The researchers also found that the effects of antibiotics on weight gain continue in adulthood and that people who often took antibiotics at a young age are probably struggling with weight more than those who received no antibiotics at all.

This link between weight gain and antibiotics becomes clear when we take into account the fact that farmers usually use penicillin to cause their animals to fatten up faster than they usually would. These animals are usually given small amounts of antibiotics each day with their food. When it comes to humans, scientists have found evidence that antibiotics affect the microorganisms that inhabit the body and help it digest food. Besides destroying what they are meant to destroy – harmful bacteria, antibiotics also destroy those bacteria that are important for gastrointestinal health. This way, antibiotics change the way the body digests food and absorbs nutrients and usually increases the number of useless calories the body absorbs.

Due to this change, weight gain is more likely to happen – and not always because you couldn’t stay away from certain foods, but because your body absorbs more calories than it would without the effects of antibiotics.

Studies conducted before the one in question showed that antibiotics can make such changes in the body in any stage of childhood, but the effect is the strongest if a child starts receiving these drugs at a very young age. The speed of weight gain increases with age, and the older a person is the harder it is to lose the weight.

As antibiotics may cause long-term negative effects on people, Schwartz says that they should be avoided unless they are really needed to treat a condition which couldn’t otherwise be treated properly.

It is essential that physicians carefully consider whether a patient can really benefit from using antibiotics at a given time or whether they would only have a negative impact on the patient’s health, and medications shouldn’t be prescribed unless they are truly necessary.