Love Your Guts—Weight Loss and Our Microbiome

Anyone who has ever had to diet knows how difficult the process can be. Weeks of denial and a nearly constant state of hunger can make dieting feel like a jail sentence. Even if we finally succeed in losing weight, within weeks afterward the weight will begin creeping up again. In fact, most dieters will regain any weight that they’ve lost within a year of their heroic struggle. Often their post-diet weight will come to exceed their weight before the diet. Even worse is the social stigma attached to obesity. Fat people bear the brunt of jokes, and cruel bullying.

If all of that weren’t insulting enough, obesity has also been linked to a greater risk of disease. Obese people are much more likely to suffer from heart disease, diabetes and high blood pressure. In fact, the concurrence of all of these conditions is so frequent that doctors have labeled it metabolic syndrome. Obesity also leads to chronic inflammation, and a higher incidence of cancer rates. All of which makes it imperative that overweight people get down to a healthier weight.

As hopeless as this seems, science is now pointing a way to finally triumphing over this struggle. The answer lies in an understanding of the the role played by our gut microbiome—the population of tiny microorganisms like bacteria, archaea and yeasts that live in our colon. Studies have demonstrated that a diverse and properly balanced microbiome can not only make dieting easier, but it can insure that the weight will be easier to keep off afterwards.

The collection of microbes that live in our gut have been likened to a major internal organ. Just considering the role our microbiome plays in regulating our appetite makes it equal in significance to any of our internal organs as far as our metabolism is concerned. By controlling when we are compelled to eat and when we feel satiated, the microbiome can determine how many calories we consume and therefore how much weight we gain. However, studies are now showing that the microbiome plays an even larger role in weight gain or loss.

Analysis of the microbiome of overweight people with insulin resistance revealed that these people have a different balance of organisms in their colon. Their microbiome contains more firmicutes organisms and fewer bacteriodetes organisms than normal healthy people. There was definitely something strange going on in the guts of obese people, but it was not yet clear whether obesity led to changes in the microbiome or whether changes in the microbiome were contributing to obesity. Subsequent studies have cleared this up this question.

Scientists extracted fecal matter from both lean and obese people. They then transferred this collection into groups of specially prepared mice. The mice were all fed the same quantity and type of food each day, carefully measured to insure that they were getting the exact same amount of calories. Over time, the mice who had been given the obese fecal transplant became obese. The mice that had received the lean fecal transplant remained thin. Obviously, the number of calories had not played a role in the weight gain since all of the mice had eaten exactly the same calorie content. The only difference between the mice was the microbiome that inhabited their colons.

The scientists concluded that an obese microbiome extracts more energy from the food, and stimulates more fat storage of the extra calories. The implication for dieters is enormous. This means that people with obese microbiomes will find it almost impossible to keep weight off. Since their microbiome is controlling their metabolic processes, in spite of their best efforts, their microbiome will work to extract the greatest amount of energy possible out of any food that they eat and store any left over calories in the form of fat. No wonder it is so difficult to lose weight.

A lean person, on the other hand, may be able to eat many more calories than necessary while their microbiome allows the extra calories to be excreted, making it difficult for them to gain weight. This makes it clear why there is so much misunderstanding between lean and overweight people. Lean people, seeing how difficult it is for them to gain weight, naturally conclude that overweight people must be eating much more food than they do in order to have put on so much weight. All the while, the obese person may be eating fewer calories than the lean person and still gaining weight!

Another significant study was conducted on identical twins. The twins who were chosen for the study had a significant difference in weight, so that one of the twins had gained enough weight to be classified as obese while the other remained lean. Identical twins have the same genetic makeup, so this was proof that genetics were not causing this disparity. The scientists analyzed the microbiota resident in the colons of the twins, and discovered a pattern. The obese twins had the same skewed ratio of firmicutes to bacteriodetes organisms in their colon that the obese insulin resistant people did in earlier studies.

Jeffrey Gordon refined the mice obesity study even further by introducing the microbiome from lean and obese twins into sterile mice, but then allowing the mice to mingle together. A common habit among mice is to eat one another’s fecal matter. In this way, the mice with the obese microbiome were able to increase the diversity of organisms in their guts. The result was that the mice that had been infused with the obese microbiome were able to supplement their microbiome with the more diverse lean microbiome. All of the mice in this experiment were able to remain lean. A diverse microbiome was the most important component in staying at a healthy weight.

This leads to the conclusion that the key to losing weight and maintaining a lean body mass is through a healthy, and diverse microbiome. There are two primary ways that we can influence the makeup of our gut microbiome. The first is to protect our microbiome from damage by avoiding the use of antibiotics whenever possible. The overuse of antibiotics is in all probability one reason for the obesity epidemic in our time. The effect has probably come about not just through human use of antibiotics, but also from eating antibiotic laden meat. Farm animals are routinely treated with antibiotics, so that those who eat meat are also constantly being dosed as well.

Another way that our microbiome can be damaged is through the consumption of processed foods. The preservatives in processed foods kills the microorganisms in our gut just as it was designed to do to the microorganisms in the food being preserved. The damage to the microbiome from antibiotic exposure and preservatives can explain how twins who live within the same household and eat the same food can end up having differing microbial makeup. One may have been exposed to more of these hazards than the other.

This brings up a pressing question. Given that our exposure to antibiotics and preservatives through our modern diet has already damaged our microbiome, is there a way to recover the diversity once damage has been done? The answer is a resounding Yes. The healing power of plant based foods can nurture our microbiome back to health. The good, healthy organisms that our body depends on are dependent on our eating sufficient wholesome foods. The nutrients in the vegetables, fruits and whole grains that we eat don’t just feed us. They also feed our microbiome.

The most important nutrient for the organisms in our gut is fiber. Though the human digestive system is unable to break down the complex carbohydrate molecules, our microbiome can. In the process of digesting these fibers, the microbes produce short-chain fatty acids like butyrate, propionate and acetate. These short-chain fatty acids are necessary for keeping our colon cells healthy. They also travel through our blood stream to feed the cells throughout our bodies, and helping to keep them healthy.

Some studies have shown that propionate in particular may be a signal to our bodies to reduce our intake of food. This may be one reason that vegans are generally leaner than omnivores and even lacto-ovovegetarians. These short-chain fatty acids have also been shown to regulate the creation of fat cells and the process of signaling to our system when it is time to store excess calories as fat. In other words, one reason that we gain weight may be the absence of these short-chain fatty acids that would signal to our bodies that it is not time to store any fuel. Research by Martin Blaser on Helicobacter pylori has revealed that it may help regulate our appetite by controlling the production of ghrelin, which stimulates hunger. There is even some evidence that our microbiome may control cravings, sending us off the the fridge at odd moments of the day or night.

The key to controlling the signals that the microbiome sends out is to eat a nutrient dense plant based diet, while avoiding saturated fat laden meats and dairy products. Foods like beans, whole grains, fruits and vegetables have more than just fiber to recommend them. They are rich in vitamins, minerals, proteins, healthy lipids and complex carbohydrates. They satisfy more than just hunger, they contain all of the building blocks our bodies need to stay healthy and lean.

In addition, a nutrient dense plant based diet is low in calories. It is a simple matter to keep from eating too much. We can eat a full plate of these wholesome foods, and even go back for seconds, without overindulging. Our caloric intake will be within a healthy range for our bodies without effort, and consequently the weight will come off without having to go hungry. We can eat as much as we want, and still lose weight!

Only by feeding the healthier organisms with the wholesome plant based foods can we insure that the correct signals are being sent from our microbiome. Our bodies will then be regulated to eat and store only the fuel that we need. Our cells will be well fed with the proper short-chain fatty-acids, so that our cells will feel satisfied. Any cravings we might have will then be for whole grains, vegetables and fruits instead of for sugary, salty or fat laden treats. Then it will be possible to maintain a healthy body weight, instead of riding the diet roller coaster for the rest of our lives.


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