Over recent years, gut bacteria have received a great deal of scientific research. They are much more important than we once thought.
We’ve long known that gut bacteria are useful and, indeed, necessary for the proper functioning of our gastrointestinal system, hence the term “good bacteria.” However, as science delves into their abilities, they seem to be more and more vital in health, and disease.
Gut bacteria have recently been linked to mood, energy levels and a whole host of parameters that seem well beyond the remit of a bacteria that live in our intestines.
However, when you consider that there are more microbes living in you than there are cells in your body, perhaps it’s not so strange that they have so much influence – that’s a pretty amazing fact, right? You are more microbe than human.
Recently researchers have been investigating the reasons behind yo-yo weight gain. In other words, when someone who is obese loses a great deal of weight, they seem to put it back on much quicker than you might expect.
In fact, previous studies have shown that when people who have long-term obesity lose significant quantities of weight by dieting, in up to 80% of cases, the weight returns within just 12 months. A depressing statistic for anyone trying to lose some fat.
If you took someone who used to be obese and put them on the same diet as someone with a normal BMI, the person who was previously obese will gain weight much quicker.
There are a number of reasons why this might be so – genes, metabolic rate etc., but those factors don’t explain the phenomenon completely.
A recent study, published in the top research Journal – Nature – examined this effect in mice. They found that the gut bacteria of obese mice retains a “memory” of when they were obese. Becoming obese makes changes in the gut bacteria – in the types of bacteria and their numbers – and these changes last for up to 5 times longer than the period of dieting. Like a huge, long obesity hangover.
Although the current study was carried out in mice, if the results are replicated in humans it could revolutionise the way that we lose weight and keep it off. Of course, keeping caloric intake down will still be crucial, as will exercise, but perhaps enlisting the help of probiotics might become standard procedure, too.
The authors of the study are quick to mention that yo-yoing weight is, most often, due to people’s failure to stick to the diet, but they also believe that gut bacteria’s role may well still be significant.
In the experiment, the researchers used two sets of mice. One set was fed a high caloric diet and became obese, the others were given a normal healthy diet. Once the high calorie mice had become obese, they switched them to a normal healthy diet.
They then waited until the obese mice were down to the same weight as the healthy mice.
Once the two sets of mice were indistinguishable in size and weight, they gave both groups access to high-fat foods. The previously obese mice were found to put weight on much more readily than the control mice, even though they consumed the same amount of food.
Now, to see whether the gut bacteria played a role, they transplanted gut bacteria from the previously obese mice, into the control mice’s guts. Once this transplantation had occurred, the mice in the control group put on weight at the same rate as the mice who had been overweight.
This shows a clear role for gut bacteria in yo-yo weight gain. Why might this be the case? Well, the researchers think that this may be an evolved mechanism that helped animals survive during times of low food. In the wild, having the ability to put weight on after a period of hunger is a positive thing.
Of course, in human society, where we have access to many more calories than we need each day, this physiological mechanism works against us.
The team of scientists continued to observe the microbiome as it slowly changed once the obese mice were on a normal diet. It took around 6 months to change from the obese-type bacteria to a more normal microbiome. That’s about a quarter of a mouse’s life. So, in humans, this could be months or even years.
That’s a sobering thought for a human dieter. However, in the future, once this change has become better understood, there may be better ways to tackle it. The researchers also note that changing the microbiome is notoriously difficult. If you just eat a couple of probiotic yoghurts, it’s not going to make much difference. It’s basically a war zone in there. Any new strains of bacteria will be out-competed by the existing colonies.
The researchers believe that, in the future, interventions might include a course of antibiotics to kill off existing strains, and then a heavy duty probiotic intervention.
Of course, the study will need to be replicated in humans before any of this takes place. Whatever the future holds, this could have important ramifications for anyone trying to shift a load of weight. But, it will still involve a load of will power and exercise… unfortunately.