Your gut bacteria play many essential roles in your health.
For starters, they help boost your immunity, digest nutrients, make vitamins, lift your mood, and more. On top of this, your gut bacteria help control your weight in several ways.
This article helps explain how your gut bacteria can affect your weight.
What are gut bacteria?
There are trillions of bacteria living inside your gut.
Collectively, they are called your gut microbiota and play a massive role in your health.
Your gut bacteria play important roles, such as (1, 2):
- Producing vitamins like vitamin K.
- Digesting nutrients, like fiber.
- Communicating with your immune system.
- Supporting brain health.
- Lifting your mood by making chemicals like serotonin — the happy hormone.
While many bacteria in your gut are friendly, some can be harmful. If your gut contains too many harmful bacteria and not enough friendly bacteria, it can cause an imbalance called gut dysbiosis (3).
Unfortunately, this imbalance has been linked to health conditions like inflammation, weight gain, obesity, inflammatory bowel disease, insulin resistance, and certain cancers (4, 5, 6).
Many factors can cause an imbalance of gut bacteria, including:
- Not eating enough fiber-rich foods.
- Not eating a diverse range of fruits, vegetables, and whole grains.
- Not exercising frequently.
- Drinking too much alcohol.
- Stress.
- Smoking.
- A lack of sleep.
Summary Your gut bacteria play important roles for your health like digesting nutrients, making vitamins, supporting your mood and brain, and aiding your immunity. However, if you have too many unhealthy gut bacteria, it can cause an imbalance that is linked to many harmful diseases.
How your gut bacteria affect your weight
Your gut bacteria can influence your weight in two key ways:
Affecting food digestion
Your gut bacteria live inside your intestines and come in contact with food.
Because of this, they can affect what nutrients you absorb and how you store energy.
For example, your gut bacteria help break down fiber and use it for food. When this happens, they make many chemicals that aid gut health and may promote weight loss (7).
Affecting your appetite
The body makes a variety of hormones that help control your appetite.
The main ones include:
- Leptin
- Ghrelin
- Peptide YY
- Glucagon-like peptide-1
Interestingly, some studies show that your gut bacteria can influence how many of these different appetite-controlling hormones you make — affecting if you feel hungry or full (8, 9).
For example, a study in 60 overweight adults found that taking propionate — a type of fiber that acts as food for your gut bacteria — for 24 weeks significantly increased levels of the peptide YY and GLP-1 — two hormones that help tell your brain that you’re full (10).
On the other hand, some research shows having too many unhealthy gut bacteria could make your body produce more ghrelin — a hunger hormone — affecting your appetite (11).
Summary Your gut bacteria can affect your weight in two key ways: affecting how food is digested and influencing your appetite.
