BY A GUEST AUTHOR -- It's holiday season and while we deck the halls and jingle the bells, we also indulge – while the average person consumes between 2,000 and 2,500 calories per day, one holiday meal can come in at over 3,000 calories.
And while we’ve always been told that how much we eat is just a matter of will power, recent research indicates that how much we eat is actually influenced by our invisible companion microbes. To a significant extent, we eat until our gut microbes say we're full.
Tens of trillions of microbes live inside our gut and perform essential services, serving crucial roles in mediating our immune systems, metabolism and central nervous system. They also assist in normal growth and development and protect us against unwanted pathogens and even affect our moods and mental states, with a direct link to depression and anxiety.
Important as well, our gut bacteria play a critical role in obesity. Two main types of bacterial strains are dominant in our gut microbiome. Obese and lean individuals differ significantly in the relative proportions of these two types.
Doctors have long assumed that our level of appetite or satiety was dependent upon circulating molecules and hormones given off by our own body cells that line our gut. As we eat and digest, those cells give off chemicals that are metabolic signals of fullness and satisfaction. They circulate to specific centers in the brain.
As our gut microbes take in nutrients from the food we eat, those circulating molecules tell us if we are full. Surprisingly, this circuit is actually dependent on their assessment of their own needs. So our gut bacteria and our own cells are both directly participating in determining both hunger and satiety.
The microbes in our stomach have a huge say on how large a meal we will eat. As we eat, our microbes are absorbing nutrients from our food, triggering a phase of rapid reproduction that lasts for about 20 minutes. After that, they switch to a slower growth phase, and send signals to our brain that they are satisfied.
It is estimated that it takes an increase of about one billion extra bacteria in the stomach and its close connections before their growth cycle switches and tells us that we've had enough to eat and we feel full.
Of course, it is not only the amount of food that counts. There is also a strong correlation between the level of fats in our diet and our brain circuits. Not everyone is affected equally, though. The level of ingested fats in our diets changes everyone's gut microbial populations, but some are affected more than others.
For those who are sensitive, fats cause inflammatory changes that irritate nerve cells that carry signals to the brain. This can lead to gut-brain miscommunication and can lead to overeating and obesity.
So this holiday season, how do we best achieve that balance? How do we keep our essential microbes in harmony with our own cells before we dive into the gingerbread, sugarplums and eggnog?
Here are five simple tips:
1. Slow down when eating. Give your microbes a chance to increase in number while you eat. Remember that they're at the table with you.
2. When you've finished that main course, step away from the table before you decide to have dessert. Waiting 20 minutes to make that decision can make a surprising difference on how likely you are to reach for the next piece of pie. It will help you resist.
3. As much as possible, try to lay off the fats.
4. Experiment with incorporating prebiotic or probiotic foods into your diet before you start the holiday food festivities. Keep taking them on a regular basis in the New Year. These types of foods help promote a healthy gut microbiome.
5. Above all, be willing to actively experiment and see what works for you. No two individuals are alike.
Dr. Bill Miller had been a physician in academic and private practice for over 30 years. He is the author of The Microcosm Within: Evolution and Extinction in the Hologenome. Dr. Miller is an internationally recognized evolutionary biologist and an expert on the emerging science of the microbiome. He serves as guest editor of a major academic biology journal and is co-editor of a forthcoming textbook on developmental and evolutionary biology.