Gut and Weight Loss
Weight loss can be hard. Diet and physical exercise are important, but they are not the whole story. It is more complex than that. We now know that many other factors can play a role either in causing weight gain or preventing weight loss. These include: inflammation, hormone imbalance, genetics, lack of sleep, stress and an imbalanced microbiome. Research shows that reduced bacterial diversity is strongly associated with weight gain, and that supporting a healthy gut may aid weight loss.
How does the gut affect weight?
The gut contains trillions of bacteria, beneficial and pathogenic. These microbes all have particular roles and collectively contribute towards overall health. They influence our energy levels by controlling the extraction of energy from the food we eat, carbohydrate fermentation, and they regulate the hormones in our gut which are involved in energy production and appetite. These microbes also affect weight by increasing inflammation and glucose absorption in the gut. Reduced microbial diversity is associated with increased gut permeability (‘leaky gut’), which in turn increases blood levels of a bacteria-derived toxin called lipopolysaccharide (LPS). LPS has been strongly linked with obesity. It mainly works by triggering whole body inflammation and oxidative stress, leading to poor glucose management, insulin resistance, and fat accumulation. The type and ratio of particular bacterial strains in your gut may affect whether you put on weight easily, or whether you have a slimmer body type, by influencing the extraction of energy from food.
What causes reduced diversity of gut bacteria?
Diet, especially one that is low in fibre and/or high in fat and sugar.
Stress
Antibiotics not only upset the microbial balance, but they have also been shown to contribute to an increased risk of obesity in adulthood when taken frequently during childhood.
How to restore bacterial diversity: prebiotics and probiotics
There are a number of studies which show a positive effect from taking probiotics on weight loss by reducing inflammation and gut permeability, as well as improving glucose management.
Prebiotic fibre is found in plants, particularly foods such as onions, garlic, asparagus and leeks. These are known as indigestible or insoluble fibre. They cannot be broken down by our digestive enzymes, so they reach the gut intact where they are fermented by our gut bacteria. This fermentation process produces short chain fatty acids (SCFAs), acetate, propionate, and butyrate, which help the gut barrier and our metabolism. The more abundant and diverse the supply of prebiotic fibre through diet, the more abundant and diverse the gut microbiome. Good production of SCFAs by our gut bacteria has been shown to protect against weight gain.
Increased fibre intake, especially the insoluble type, has been shown to reduce your appetite ie you feel fuller and less hungry. (For those that want to know how, a type of prebiotic called inulin increases satiety by modulating hormones involved in regulating appetite). This may then help reduce calorie intake and snacking, further supporting weight loss. As well as increasing the total quantity of fibre in your diet, it’s important to include a variety of different types from a variety of food to support gut bacterial diversity.