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Can Antibiotics Make Your Weight Fluctuate?

Obesity is a growing concern across the world and there are several studies focused on identifying the role of gastrointestinal factors.1

Many different factors influence your weight and some medicines can be responsible for weight fluctuations. Can antibiotics make your weight fluctuate? This is a commonly asked question, which needs to be understood in detail.

Several studies have studied the exposure to antibiotics in early life and the possible link with the risk of weight gain. Many studies have also been conducted to assess the link between antibiotic intake and the risk of weight gain in adulthood.

Can Antibiotics Make Your Weight Fluctuate?

While antibiotics are often associated with side effects like nausea or gastric disturbances, there is a rising concern that they may influence your weight too. Studies aimed at evaluating this problem have reported varying results and further investigations are needed.

Use of Antibiotics in Childhood and Weight Gain

There are findings from previous studies that the use of antibiotics in infants and growing children can harm their weight. While the use of antibiotics is sometimes necessary, in some cases it may be used more than required. If antibiotics can make your weight fluctuate it is indeed a concern, particularly in the case of children.

A study conducted in 2017 primarily aimed at evaluating the possible association between the use of antibiotics, weight gain, and obesity.1 This study was based on the findings that antibiotics can modify the diversity and composition of the gut microbe, which can be a contributing factor in influencing body weight. It leads to an understanding that the use of antibiotic therapies for the treatment of various illnesses may be contributing to the increasing prevalence of obesity.1

This explains an answer to the question can antibiotics make your weight fluctuate?

In another study done by the Johns Hopkins Bloomberg School of Public Health research, it was reported that kids who receive antibiotics during their childhood can gain weight faster than kids who don’t. The experts stated that when antibiotics are taken by children, they can alter their BMI forever. It was noted that by the age of 15 years, children who had taken antibiotics seven times or more times during childhood had a weight that was three pounds more than those children who did not receive antibiotics in childhood.2

While earlier studies had mentioned the use of antibiotics in infants and the risk of obesity, this study reported that the use of antibiotics at any age during childhood can contribute to weight gain that can increase with age.2

The chances of antibiotics can make fluctuate the weight in children is found to be linked to some parameters3 like

  • Use of antibiotics in the first six months of life
  • Repeated exposure to antibiotics for more than three courses
  • Use of broad-spectrum antibiotics for treatment
  • Male gender

Use of Antibiotics in Adulthood and Weight Gain

As the use of antibiotics in early life is known to affect weight gain, their use in adulthood needs to be studied to understand its impact on weight fluctuations in adults.

A 2019 study concluded that chronic use of antibiotics in adulthood can have long-lasting effects on BMI. The link between antibiotics and weight fluctuation may differ based on the class of antibiotics. The main understanding is that chronic and frequent use of antibiotics can have a great impact on the gut microbiome, which is the difference between obese and lean people.4

Some of the possible mechanisms by which antibiotics can make your weight fluctuate include3

  • An increased ability of some gut bacteria to extract energy from indigestible polysaccharides
  • Some changes in the hepatic lipogenesis
  • A decrease in the bacteria that can be protective against obesity
  • A decrease in the intestinal defense can affect the beneficial pathways of metabolism and immunity

However, some studies have reported that the use of antibiotics was not associated with weight gain in certain cases, while some studies have shown that antibiotics can lead to weight loss.

A 2016 study reported that the long-term use of antibiotics in healthy adolescents with acne was not associated with weight gain.5 While there are several factors affecting weight in adolescents, more detailed studies in this respect are needed.

A study conducted in 2020 showed that antibiotics can result in weight loss by impairing gut microbiota in mice. Antibiotics like ceftriaxone can significantly alter the intestinal microbiota, which can greatly affect the growth of the host animal by causing delayed weight gain. In such cases, the use of Lactobacilli can help stimulate the growth of intestinal bacteria and reduce the side effects of antibiotics.6

Thus, the query of whether antibiotics can make your weight fluctuate is an important thing to be considered. Based on most of the studies, it is clear that antibiotics can make your weight fluctuate, as in some cases there can be weight gain, while in some there can be weight loss.

Antibiotics are an important treatment option for several infections; however, it is important to understand when their use is necessary and when they can be avoided. This will not only help control antibiotic resistance but also help reduce the associated side effects. While antibiotics can make your weight fluctuate, the manner and severity depend on various factors. So, maintaining a healthy diet and routine, preventing infections, and using antibiotics only as prescribed by your doctor are important to protect your health.


Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:December 14, 2022

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