Do Antibiotics Make You Gain Weight

antibiotics and weight gain

Medications known as antibiotics are employed to treat bacterial infections. They can save lives and prevent serious pneumonia, meningitis, and sepsis complications. However, antibiotics can also have unwanted side effects, such as nausea, diarrhoea, allergic reactions, and resistance. One of the most common questions about antibiotics is whether they can make you gain weight. This article will explore the possible link between antibiotics and weight gain and how to prevent it.

Do Antibiotics Make You Gain Weight?

antibiotics and weight gain

Antibiotics, such as those prescribed for strep throat, urinary tract infections, and pneumonia, serve as drugs to treat bacterial infections. Their mechanism involves either killing or halting the growth of harmful bacteria in your body. However, antibiotics can also affect the balance of good and bad bacteria in your gut, known as the microbiome. Playing crucial roles in digestion, immunity, metabolism, and mood, the microbiome holds significant importance.

Some studies have suggested that antibiotics can cause weight gain by altering the microbiome and increasing the amount of sugar absorbed from food. This can increase appetite, cravings, inflammation, and insulin resistance. Additionally, antibiotics can affect the production of hormones that regulate hunger and satiety, such as ghrelin and leptin. When you are full or hungry, these hormones signal to your brain; when disrupted, you may eat more than you need.

However, not all antibiotics have the same effect on weight. Some antibiotics may have a more pronounced impact on the microbiome than others, depending on the type, dose, duration, and frequency of use. Also, some people may be more susceptible to weight gain from antibiotics than others, depending on their genetic makeup, lifestyle factors, and pre-existing health conditions. Therefore, it is important to consult your doctor before taking antibiotics and follow their instructions carefully.

If you have gained weight after taking antibiotics, there are some things you can do to restore your gut health and lose excess pounds. Here are four tips to help you:

  • Eat probiotic foods: Live microorganisms constitute probiotics that can benefit your gut by replenishing the good bacteria and restoring the microbiome balance. Some examples of probiotic foods are yoghurt, kefir, sauerkraut, kimchi, kombucha, and miso. You can also take probiotic supplements if you prefer, but choose a high-quality product with a variety of strains and a sufficient amount of CFUs (colony-forming units).
  • Eat prebiotic foods: Prebiotics are substances that feed the good bacteria in your gut and help them grow and thrive. Prebiotic foods include garlic, onion, leek, asparagus, banana, apple, oats, barley, and flaxseed. You can also take prebiotic supplements, but consult your doctor first.
  • Eat a balanced diet: A well-balanced diet rich in fibre, protein, healthy fats, vitamins, minerals, and antioxidants can help your gut heal and support your weight loss goals. Fibre can help you feel full longer and prevent overeating. Protein can help you build muscle and boost your metabolism. Healthy fats can help you regulate your hormones and reduce inflammation. Vitamins, minerals, and antioxidants can help you fight infections and oxidative stress. Some foods containing these nutrients are fruits, vegetables, nuts, seeds, beans, lentils, eggs, fish, poultry, and olive oil.
  • Exercise regularly: Engaging in exercise aids in burning calories and fat, improving your mood and energy levels, and strengthening your immune system and muscles. Additionally, it has the potential to stimulate the generation of fresh brain cells, leading to improved cognitive function. Strive to achieve a minimum of 150 minutes per week of moderate-intensity aerobic exercise, like brisk walking, 75 minutes per week of vigorous-intensity aerobic activity, such as running, or a blend of both. You can also add resistance training (such as lifting weights) to increase muscle mass and metabolism.

How do antibiotics affect gut health?

antibiotics and weight gain

One of the ways that antibiotics can affect your weight is by altering your gut health. Your gut is home to trillions of microorganisms, collectively known as the microbiome. These microorganisms are vital to digestion, immunity, metabolism, and mood. Their functions include breaking down food, generating vitamins and hormones, combating pathogens, and regulating appetite.

Antibiotics can kill the harmful bacteria that cause infections and the beneficial bacteria that live in your gut. This can disrupt the balance of your microbiome and cause dysbiosis, a condition where the bad bacteria outnumber the good ones. Dysbiosis can lead to inflammation, leaky gut syndrome, and impaired nutrient absorption.

By acting together, these factors can contribute to weight gain, increasing your hunger, slowing your metabolism, and causing you to store more fat. Some studies have shown that people who take antibiotics frequently or for long periods are more likely to be overweight or obese than those who do not.

Read here: How to Improve Gut Health Naturally: 10 Research-Backed Tips.

How do antibiotics increase hunger?

Another way that antibiotics can affect your weight is by increasing your hunger. This is because antibiotics can interfere with the production and regulation of ghrelin, a hormone that makes you feel hungry. Ghrelin is secreted in the stomach and signals to the brain to stimulate appetite. Typically, ghrelin levels increase before meals and decrease after eating.

However, taking antibiotics can disrupt the feedback loop between the stomach and the brain and cause ghrelin levels to remain high even after eating. This can make you feel hungrier than usual and cause you to overeat. Some studies have shown that antibiotics can increase ghrelin levels by up to 6 times in mice and humans.

Antibiotics can also affect the production and regulation of leptin, a hormone that makes you feel full. Fat cells secrete leptin, which then signals the brain to suppress appetite. Normally, leptin levels rise as you gain weight and fall as you lose weight.

However, taking antibiotics can reduce your brain’s sensitivity to leptin and make you feel less satisfied after eating. This can also make you feel hungrier than usual and cause you to overeat. Some studies have shown that antibiotics can decrease leptin sensitivity by up to 50% in mice and humans.

See also: Healthy Brain and Heart Pack.

How can I prevent weight gain from antibiotics?

The good news is that there are some ways that you can prevent weight gain from antibiotics. Here are some tips that you can follow:

  • Take probiotics: Beneficial bacteria known as probiotics aid in restoring your microbiome’s balance and enhancing digestion. Probiotics can be found in foods like yoghurt, kefir, kimchi, sauerkraut, kombucha, or supplements. It would be best to take probiotics during and after your antibiotic course to replenish the good bacteria in your gut.
  • Eat a healthy diet: It is highly recommended to consume a nutritious diet rich in fibre, protein, and healthy fats and low in sugar, refined carbs, and processed foods. Fibre can help feed the good bacteria in your gut and keep you feeling full. Protein and healthy fats can also help regulate your appetite and metabolism. You should avoid foods high in sugar, refined carbs, and processed foods, as they can feed the bad bacteria in your gut and cause inflammation and weight gain.
  • Drink plenty of water: To observe adequate hydration and effectively flush out toxins, it is advisable to drink ample fluids. Water can also help curb your hunger and boost your metabolism. You should aim for at least eight glasses of water per day.
  • Exercise regularly: You should exercise regularly to burn calories and fat and improve your mood and energy levels. Exercise can also help balance your hormones and reduce inflammation. You should aim for at least 30 minutes of moderate to vigorous physical activity daily.


Antibiotics are powerful drugs that can treat bacterial infections but can also negatively affect your weight. Antibiotics can affect your gut health and hunger hormones and make you gain weight. However, you can prevent weight gain from antibiotics by taking probiotics, eating a healthy diet, drinking plenty of water, and exercising regularly. Following these tips can maintain weight and health while taking antibiotics.

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