We know that exercise is good for us. We know that it has a whole range of physical and psychological benefits. But did you know that the type of exercise you do actually affects your gut microbiome? The gut microbiome is the bacteria that live in your intestines. They are responsible for almost all aspects of your health. We’re supposed to have trillions of bacteria living in our gut and, in a healthy gut, these are made up of somewhere around 500 different species.
Many things affect the amount and variation of our gut flora, such as whether you were born vaginally or by cesarian. Even your first moments in the world will have a huge effect on your biological make-up; exposure to antibiotics, both while in the womb and as a young child; your environment; exposure to toxins, like glyphosate, in your food, the soil, the water or the air; your diet and your exercise.
This is a topic all to itself, and it is on my schedule to cover later in the year, but here's a quick summary. Gut health is basically how well your gut absorbs nutrients from your food and passes them into your body. It's also how well your gut keeps everything else in so that it can pass to your bowels and leave. At the moment, around 80% of Americans have “leaky gut”, meaning their gut doesn’t keep things in that it should. It allows undigested food particles and toxins to seep through into the bloodstream.
These things, even though they may be part of exceptionally healthy foods, are not supposed to be there. When a foreign body, even one from something that’s awesome for us like kale, gets into a part of the body it’s not supposed to be in, it triggers an immune response. This immune response then creates inflammation, allergies, aches and pains. Many of things that we just take for granted as being how we feel. We may put it down to getting older or just being tired from work. Actually it’s from having permeable gut junctions and it’s avoidable. One huge way of curing a leaky gut is through diet and removing inflammatory foods so that your gut has a chance to heal. Another is exercise.
How The Gut Microbiome Affects Our Body
Body composition is the ratio of lean tissue to fat that your body’s made up of. Generally, less fat and more lean muscle is indicative of a healthy body composition. What’s really interesting is that the gut microbiome of a person with healthy body composition is vastly different from that of an obese person. There have been studies done, mostly in mice, that have proven if you take the gut microbiome from a healthy person and an obese person and put them into nude mice (mice bred with no immunity of their own and raised in sterile conditions), the mouse that got the healthy gut flora is not able to be overfed. However, the mouse that got the obese gut flora becomes obese, even on the exact same diet and exercise regime as the slim mouse. This shows that gut microbiome has a huge impact on our weight and health.
If you’re now reading this and thinking “oh well, I have an overweight microbiome, I’m doomed” don’t despair! There are things you can do to change your gut microbiome and, coincidentally or not, they’re much of the same things that you’d do to get healthy anyway. One of those things is exercise.
Altering The Gut Microbiome With Exercise
Now, before you go rushing off to the gym or out in the rain for a run, let’s take a minute to look at the most effective way to get the results we want. Just like with other fitness goals, when it comes to altering your gut microbiome, not all exercises are created equal. Some are more equal than other.
High Intensity Interval Training (HIIT)
HIIT is not as scary as it sounds. We’ve all seen those crazy people doing HIIT where they’re jumping up and down, dropping to the ground, jumping back up again… HIIT is all about intensity and recovery and intensity is relevant to your fitness level. As long as you are working as hard as you possibly can for the short interval of exercising, then that counts. You then follow this by a period of rest. The timings are also not set in stone. You could work out for anything from 30 seconds to 3 minutes and rest even up to 5 minutes between sets. The important thing is to work at very nearly your maximum for as long as you can (if you can do it for more than 2 minutes, you’re probably not working at your maximum) then rest long enough for your heart rate to recover.
The results from doing HIIT rather than a slower paced training can be seen in just 2 weeks. That’s 6 sessions. In this time your insulin response increases dramatically. So much so that if you’re prediabetic or have type 2 diabetes, it’s possible to get it down the match that of healthy people. As well as insulin responses, HIIT causes changes in the ratio of certain bacteria species in the gut, creating a microbiome similar to that of a lean person in just 6 weeks, even in the case of obesity. Obviously in 6 weeks, a person is not going to go from obese to a healthy weight, but their gut flora now resembles more closely that of a lean person than of an obese person. From here, it’s then much easier for your body to adjust its composition to match.
When it comes to changing your body composition, strength training is the gold standard or workouts for it. Weightlifting is the main way to sculpt your body. You can focus on isolated area and work on them individually to get the shape you want. If you lift weights, you can build up your chest and leg muscles, get rounder shoulders, bigger arms, more butt… Cardiovascular exercises just burn calories and work your heart and lungs. This is great for you and important to keep your cardiovascular system healthy and your brain functioning optimally. However, it won’t change your body shape other than to reduce some fat. With strength training you have much more control over your body and increasing the lean muscle to fat ratio is what’s going to make all the difference.
We actually burn most of our calories while we’re at rest. This is a direct result of how much muscle we have compared to fat tissue. More muscle tissue means higher resting metabolic rate so more calories are burned doing pretty much everything because there’s more muscle to maintain while doing these things. Strength training also has a higher post-exercise oxygen consumption. This means that it burns more calories after your finish exercising compared to cardio. Along with the standard benefits of weightlifting like reduced cholesterol, improved heart health, better bone density, etc. the gut microbiome of those who regularly do strength training shows great diversity and diversity is good. A diverse gut is a healthy gut.
Dynamic Flexibility Training
Dynamic flexibility training include things such as PiYo, pilates and some forms of yoga. The important thing about dynamic flexibility training is the dynamic part. It must include continuous movement and should be restorative rather than difficult. You should feel relaxed at the end of it, not relieved that it’s over. The last defining factor is that it must be a full body workout. You should get a full range of motion from all of your body parts. Rather than getting into a stretch and holding it, you move constantly through the motion. This keeps your body’s core temperature high while improving the range of motion around your joints and flexibility and strength in your muscles. This form of exercise increases blood flow to your muscles, joints and digestive system without creating the stress responses that other forms of exercise produce in your adrenal system.
Stress has a huge impact on our gut microbiome and the diversity of the bacteria that live there. By taking some time to do something restorative to your body, it helps to balance out the stress hormones that are floating around. This keeps your gut healthy so that it can regulate your immune responses appropriately.
Long bouts of cardio that last more than 45 minutes are endurance activity. In our gut health ranking, endurance exercise comes last as a recommendation. In fact, there is some evidence that it’s actually damaging to your gut health to do prolonged cardiovascular exercise. It reduces blood flow to your digestive tract and increases gut permeability, which means that things like undigested food, toxins and bacteria are able to leave your gut and travel to other parts of your body where they’ll cause trouble. Endurance exercises also decreases gut thickness and nutrients to the digestive tract. There’s also an increase in inflammatory immune responses as well as dehydration. Oxidative stress also increases with endurance exercise. This is where unstable oxygen atoms steal electrons from other molecules, making them become unstable and break down. Rusting is a form of oxidative stress on iron.
Now, don’t go throwing out your running shoes. Any exercise is better than no exercise and cardiorespiratory fitness was positively correlated to a more diverse gut microbiome. It depends on your goals. If your goal is to increase your endurance, then clearly endurance exercises are the thing to do. But if your goal is improved gut health and body composition, then there are better ways.
So Which One Is Best?
Just like with diet, there’s no one single exercise that’s best for your gut health and body composition. The best thing to do is to phase your exercise as you would phase your diet. Our bodies are fantastic at adapting to whatever environment they’re in. If you restrict your calories, your body will alter its functions so that it only uses as many calories as you give it. This is why restrictive diets never work. It’s the same with exercise. You’re body will adjust to what you’re asking it to do and you’ll find yourself plateauing with your results. You need to change things up to keep your body on its toes, so to speak.
The best way to do this is to combine HIIT, strength training and dynamic stretching and flexibility training as a regular part of your workout. If you want to do endurance training, if you just love the feeling of running long distances and it makes you happy, the do that too. Try and add it in as part of a diverse workout programme and do it infrequently rather than having it be the only thing you do. If you need some inspiration, click the button below for a 2 week workout plan that incorporates all the elements of keeping fit and strong as well as keeping your gut happy.
Ultimately, though, the best form of exercise is one that you will actually do. Pick something you will continue to do without feeling like you're being tortured every time you do it. Exercise should be fun and make you feel good.
For an example workout schedule that incorporates the main exercise types we talked about, just click here. I’ll send you a 2 week recommended workout plan straight to your e-mail. Or if you want to have something more personalised, get in touch and I can help you find the perfect plan for reaching your health and fitness goals. The ultimate you is right there within your reach!