The Truth Behind Gut Health and Weight Loss

“The Truth Behind Gut Health and Weight Loss” was written by Emily Zhang and reviewed/edited by Kasey Hageman MS, RD, LD. Emily is a dietetic student at Hunter College.

Have you ever wondered, “Does gut health and weight loss coincide?’

The simple answer to this question, is yes, research shows that your gut health can affect your weight.

What is the gut?

The gut. What is it? Most people usually understand the “gut” to be referring to the intestines.

Actually, “the gut” includes much more than just that. The gut, also referred to as the gastrointestinal tract, extends from the mouth to the anus. This means that the stomach, pancreas, liver, gallbladder, small and large intestines are part of the gut. 

The gut contains an entire population of bacterial species or microorganisms. In short, this population is the microbiota.

Now, I know you might be thinking, “But, bacteria is bad and causes disease”. And that is true, but NOT ALL bacteria is bad.

Yes, some species of bacteria can cause sickness and disease but the bacteria in a normal healthy gut is important for maintaining overall health.

In fact, gut bacteria help with the digestion and absorption of foods and protects against invasive pathogenic bacteria. Similarly, the microorganisms also function to produce some vitamins and assist in strengthening the immune system.

The makeup of a person’s microbiota is unique to each individual and can be influenced by many factors, especially diet. That being said, a compromised gut affects your immune system, physical and mental well-being, and possible GI diseases.

What factors affect the gut?

The early makeup of your gut microbiome is dependent on the type of delivery at birth. Natural birth is usually associated with a larger amount and a more diverse microbiome. This is because the baby comes in contact with the mother’s gut bacteria.

The diet in infant years to adulthood can then build on this. Breast milk during infant years has shown to be more beneficial to the gut than formula. The compounds present in breast milk play a strong role in nutrient digestion and absorption, immune protection, and act as a defender against bacteria in an infant. 

Antibiotics can dramatically affect your gut bacteria. Although antibiotics are usually prescribed for infections and getting rid of bad bacteria, the good bacteria are also affected.

Antibiotics can cause a decrease in good gut bacteria. In addition, they can make it difficult for some types of bacteria to recover. This is why it is important to only take antibiotics when necessary and prescribed by your doctor.

Food for gut health and weight loss

Your food choices directly impact the bacterial environment in your gut. So, frequently eating foods that are not good for the gut will result in gut imbalance and often disease development. For example, a diet high fiber and whole foods is more beneficial than a diet including in alcohol, caffeine, and fried foods. Therefore, fiber is one of the best foods for gut health. 

However, this does not mean you are not allowed to enjoy a cup of coffee. Instead, just remember to also eat your fruits and veggies in so the good bacteria are “fed.” If they are fed, they can combat any bad bacteria coming in!

Best foods for gut health

Complex carbohydrates, or fiber, have beneficial effects on health conditions such as obesity, irritable bowel syndrome, and asthma.

Dietary fiber promotes good bacteria in the intestines and increases fecal bulk. Fiber also helps with short-chain fatty acid (SCFA) production, which helps shape the intestinal environment. When there are more good bacteria, the ratio of bad to good bacteria will decrease.

The types of protein you eat can also affect the type of bacteria that will grow. Different proteins will fuel the growth of different bacteria. Generally, animal-based protein increase risk for some health conditions, such as atherosclerosis, diabetes, and obesity.

On the contrary, consuming plant proteins can combat this risk. Plant proteins decrease the risk of obesity and type 2 diabetes. Proteins from seafood and milk also have fewer obesogenic effects than animal protein. 

There is not much research on how fat or lipids affect the gut. However, the general guideline is to focus on the type of fats you consume. Eating more unsaturated fats than saturated and trans fats can help improve gut health

Fruits & Vegetables and gut health

Fruits and vegetables contain polyphenols and micronutrients. These nutrients are antioxidant, anti-inflammatory, cardioprotective, cancer preventive, and neuroprotective.

For these reasons, fruits and vegetables are the best foods for gut health and can help restore gut health. In conclusion, fruits and vegetables increase the production of SCFAs and promote good bacterial growth.

Artificial substances are things like preservatives and food additives. These products are something you should be cautious of.

Ultra-processed foods are related to a higher risk of gastrointestinal disorders. This is due to its impact on the gut environment. The typical Western diet is high in fat and carbs. In addition, it is recognized as a risk factor for inflammatory disorders.

What are prebiotics and probiotics?

Many people take probiotics and prebiotic supplements to optimize digestion and gut health. This is a great way to supplement your diet.

You can also consume foods that contain probiotics and prebiotics. Probiotics are live organisms that can provide benefits to the GI tract. Fermented foods “feed” the good bacteria to help them grow and multiply.

Some examples of fermented foods are yogurt, kombucha, and kimchi. Probiotics are also sold as supplements. Foods high in dietary fiber contain prebiotics. But, these high fiber foods cannot be digested.

Gut health and weight loss

Research has shown that a high risk for obesity can be related to low diversity of microbiota.

Obesity can also influence how your body utilizes and expends energy. Therefore, a high fat and high carb diet may promote an increase of bacteria linked to obesity.

By consuming foods that are best for your gut health, you can change the microbiota make-up, facilitate weight loss, and prevent obesity!

Factors that affect sports performance

Exercise improves the diversity of the microbiota by stimulating good bacterial growth and protecting against pathogens. Studies show that an athlete’s gut microbiome is primed for tissue repair and has a greater ability to harness energy from the diet. 

Probiotics benefit athlete performance, the gut barrier, and nutrient absorption. Probiotic supplementation can reduce instances of infection or sickness, which will enable athletes to train more often and harder.

Probiotics also improve muscle recovery, decrease soreness, and therefore lead to better performance. It also reduces the severity of respiratory infection and GI discomfort if they were to occur. 

The bottom line: how to improve gut health for weight loss

The takeaway is to focus on your daily diet and lifestyle. Reducing your intake of high-fat and high-carb foods will be beneficial to your overall gut health.

Whole foods (fruits, vegetables, whole grains, lean proteins, beans, legumes and dairy products), foods high in fiber, and foods containing probiotics are linked to the best gut health outcomes.

Exercising regularly, reducing stress as much as possible, getting good sleep, and only taking antibiotics when prescribed by a doctor can improve your gut health and your athletic performance. 


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