Yes, they can! But how?
Let’s start with the weight. Gut bacteria participate in the energy balance of the hosting human. Some species promote increased energy harvesting and fat storage, while others don’t. In other words, if your gut is dominated by such “hungry” bacteria, you might struggle to maintain or lose weight.
Numerous studies observed a striking difference in the composition of gut bacteria between lean and obese individuals. Interestingly, transplantation of the bacterial community from a lean person to an obese one often promotes weight loss. Similarly, when lean individuals receive microbiota from obese donors, their weight tends to increase.
What about diabetes?
Gut microbiota has been strongly implicated in the development of this disease too. As a matter of fact, at least 4 different underlying mechanisms have been discovered to date. I will only focus on the most well-studied and well-documented one: chronic low-grade systemic inflammation.
It’s worth mentioning, that inflammation as such is not a bad thing. It is body’s normal reaction to an injury and part of our natural defence system. The problems start when inflammation becomes a long-term (chronic), rather than a short-term process.
Certain bacterial species drive low-grade chronic inflammation by generating harmful compounds called lipopolysaccharides or LPS for short. LPS find their way from the gut into the blood circulation and gain access to organs and tissues. Their binding to cellular receptors puts inflammatory pathways into motion. Inflammatory molecules generated in the process interfere with insulin signalling eventually contributing to insulin resistance and diabetes.
Although both obesity and diabetes are lifestyle diseases, stemming primarily from bad diet and sedentary lifestyle, there is also no denying the fact that gut microbiota has emerged as a crucial player in the development of these pathologies. So if you want to know how to nurture health-promoting rather than disease-causing bacteria in your gut, stay tuned for the next post.