The health of our gut is fast being recognised as being crucial for overall health and weight loss. This largely comes down to the gut microbiome, which are the trillions of bacteria, fungi and other microorganisms that live in the digestive system. The microbiome are involved not only with supporting digestive health, but other areas of health including mental health, immune function and even metabolism.
In particular, the link between the health of our gut and weight has been more recently researched. We will discuss the mechanisms underlying this relationship and provide insights on optimising gut health in the aim to support sustainable weight management.
How are the gut and metabolism linked?
The microbes found in the gut have a role in breaking down the foods that we consume, including complex carbohydrates and fibres, proteins and fats. Many of these foods are broken down into short chain fatty acids (SCFA’s), known as butyrate, propionate and acetate. These SCFA’s play a key role in supporting our energy and metabolism, and can help support insulin sensitivity, reduce fat storage and increase energy expenditure. The SCFA’s have even been shown to influence the appetite-regulating hormones, such as ghrelin and leptin.
An overgrowth of unhealthy bacteria can lead to metabolic impairment of these pathways, which can contribute to increased fat storage and reduced energy expenditure.
We know from research that the gut microbiome composition can differ significantly even between lean and obese twins, with the leaner twin showing a more diverse and balanced microbiota.
Inflammation, weight loss and gut health
Inflammation is often described as something negative and harmful, but in actual fact, an inflammatory response is the natural immune response to an infection or injury. It is crucial to have this inflammatory response when we have an acute injury or infection, as it allows the defence mechanisms of the immune cells to reduce risk of complications and support the healing process. So, in the short term, this acute inflammation is good.
However, chronic inflammation is different. It can develop without response to injury or infection and will be long lasting, causing harm. Chronic inflammation increases risk of obesity and metabolic disorders such as type 2 diabetes and cardiovascular diseases such as stroke.
The gut plays an important role in regulating inflammation, through the production of anti-inflammatory metabolites, some of which are the SCFA’s mentioned earlier. Other metabolites include components of the bacteria’s themselves. These can support the maintenance of the gut epithelium (and integrity of the gut wall), as well as interact with several key immune cells.
The gut also provides a natural defence against pathogens (harmful microorganisms) through the maintenance of the mucosa. This is in contact with the immune system, which can then lead to anti-inflammatory mechanisms, to inhibit inflammation. However, certain bacteria can promote the leakage of metabolites from the gut and into the blood stream, which can then lead to an inflammatory response. Diet and weight can have a role to play in this balance of inflammation and anti-inflammatory response controlled by the gut, where studies have shown that those with obesity and a high fat intake have higher levels of increased gut permeability.
Gut bacteria and appetite regulation
Appetite is influenced largely by the hunger and satiety signals that are released from the stomach, via signals from the brain. However, it has been shown that the gut microbiome can also influence these signals by interacting with this gut brain axis, which can indicate that there are specific bacteria’s in the gut that can predict your chances at weight loss.
Certain bacteria such as Bacteroidetes and Firmicutes, play a role in producing neurotransmitters like dopamine and serotonin, which also have an influence on mood and eating behaviours. Bacteroidetes are associated with those who are leaner and have improved metabolic health, whereas Firmicutes are associated with increased energy extraction from foods, meaning more calories are absorbed. The gut microbiome in those who are overweight exhibit decreased diversity with lower levels of Bacteroidetes and higher levels of Firmicutes. Fat mass and waist circumference was also positively correlated with the Firmicutes bacteria. This suggests that the composition of gut bacteria can have a significant impact in weight regulation.
How can diet support the gut microbiome
What we eat is the main influence of shaping the gut microbiome composition and functions. Typical Western diets involve high levels of refined sugars, processed foods and saturated fats, which promotes the growth of harmful bacteria, dysbiosis and metabolic dysregulation, all of which discourage weight loss. However, diets rich in fibre, healthy fats, and polyphenols can promote a healthier and more diverse microbiome.
Here are our top 5 tips for supporting gut health and prioritising a healthy weight:
Reduce added sugars and ultra processed foods
Foods such as cakes, biscuits, doughnuts and chocolate are high in added sugars. In addition to this, ultra processed foods like pizzas, crisps, flavoured yoghurts, ready meals and cured meats can significantly contribute to the imbalance of harmful bacteria in the gut. Instead of feeling like you can never have these foods, work on replacing some of these with whole foods, which includes cooking from scratch more often or using less processed alternatives. For example, switch your higher sugar flavoured yoghurt for a plain Greek yoghurt with fresh or frozen berries and a drizzle of honey. Or instead of buying a takeaway pizza, make your own using a simple pre-made plain pizza base, topping with homemade tomato sauce, vegetables and cheese.
Increase fibre intake
Fibre is a type of prebiotic that feeds the gut bacteria, allowing for increased SCFA production. Plant foods are a rich source of fibre. This includes pulses and beans, all fruits and vegetables, whole grains, nuts and seeds.
Start off slow and increase your fibre intake over time. This could be by switching to a whole grain cereal for breakfast, or adding a snack of berries & nuts mid afternoon, or including an extra serving of roasted vegetables for your evening meal.
Add in fermented foods
These foods (and drinks) have been produced to allow a controlled growth of microbes in the product, which are said to be beneficial – these are usually bacteria’s or yeasts. Examples of fermented foods include Greek yoghurt, kefir, kimchi, sauerkraut, kombucha and miso. These foods often contain probiotics, which can support the growth of beneficial bacteria in the gut, as well as reducing risk of certain health concerns such as type 2 diabetes. Experiment with fermented foods by adding one option in do your diet and build up the variety. Perhaps you can start with live Greek yoghurt or kefir with oats or in a smoothie, or add in chopped kimchi to your rice or stir fry.
Choose healthy fats
The type of fat matters. Increase your intake of unsaturated fats, found mostly in plant foods like nuts, olives, avocado and olive oil. Another type of unsaturated fat is known as omega 3 fatty acids, which are found in oily fish like salmon and mackerel, walnuts and chia seeds. These have strong anti-inflammatory properties and can support gut microbiome diversity. Aim to get a regular source of healthy fats in each meal across the day.
Increase intake of polyphenols
These are compounds found in plant foods, that are strongly linked to having pre and pro-biotic like effects, to support gut health. Polyphenols also act like antioxidants, helping to protect our cells from damage caused by free radicals. Free radicals are harmful as they can damage DNA, leading to increased risk of mutations. They are often found from processed meats and foods high in refined sugars, however other sources such as smoking, pollution and drugs can lead to free radical production. Polyphenol rich foods include berries, dark chocolate, green tea, coffee, flaxseeds, nuts, apples and broccoli, but they can be found in many other plant foods.
Aside from diet, what else influences gut health and weight loss?
Although the dietary choices we make are well established to impact gut health and therefore weight loss, we also know that there are several other lifestyle habits that can influence strongly on weight management and gut health.
Focusing on the following lifestyle recommendations will complement the dietary recommendations above, to best support your gut health and weight loss:
Stress management
High levels of stress can disrupt the balance of microbes in the gut. It’s been shown that stress and depression can alter the composition of bacteria through the act of stress hormones and chronic inflammation. This can increase the release of toxins and metabolites from the gut bacteria’s, which can lead to negative associations with mood and eating behaviours.
Work on regular practice of stress management techniques, which include exercise, deep breathing, meditation and mindfulness tasks, in order to support a healthier level of stress.
Sleep prioritisation
We know how important good quality sleep is for energy levels, but poor sleep has also been linked to gut dysbiosis and increased risk of obesity! Loss of sleep can negatively influence health outcomes including immune response, which can leave us more vulnerable to metabolic disease. Persistent jet lag has been shown to also have an impact on the bacteria composition, which can be linked to gut dysbiosis and a worsening of health outcomes.
Therefore, it is important to work on maintaining a good sleep routine and sleep hygiene. This includes all the regular recommendations of reducing screen time and creating a calm and relaxing environment, but it also can help to look at the temperature of your bedroom and thinking about blackout curtains/blinds, to ensure you are well rested and can maximise sleep quality throughout the night.
Regular physical activity
Any form of exercise is good for us. Not only to help with our metabolic health, but exercise can also support the microbial diversity, increasing the growth of beneficial bacteria’s. Regular exercise can have a protective effect on certain diseases, including colon cancer and inflammatory bowel disease. A study in elite rugby players showed exercise enriched the diversity of their gut microbiome and also correlated positively in protein intake. This showed that both diet and exercise can support microbial diversity in the gut.
Finding the right type of exercise is important and very personal. Explore different types of movement and exercise to find firstly what you enjoy doing, and what is also realistic for you to regularly do. This can even be walking around your local park, going for a swim, cycling, or participating in kickboxing classes – something to keep you moving and increase your heart rate.
Minimise antibiotic use
We are not saying to avoid any antibiotic treatment, if you have been prescribed it by a medical professional. Antibiotics can sometimes be absolutely necessary, however there is trend of them being overused and over relied on to help solve a range of health issues. The issue with constant antibiotic use is that they target not only the harmful bacteria, but also the healthy bacteria. This can lead to a disruption of the balance of health bacteria, and possibly a risk of developing antibiotic resistance.
Antibiotics can lead to a decline in diversity of bacteria as well as an increased risk of antibiotic associated diarrhoea (AAD). The alteration of the gut bacteria can then increase risk of health concerns such as obesity and allergies.
Mindful eating
Although choosing healthier foods is part of the solution, being aware of how we eat and how much we need to consume is also important. Mindful eating is the act of becoming fully connected with sensations experienced whilst we enjoy food. This includes being able to slow down when eating, chewing each bite thoroughly to savour all the flavours and tastes. It also means paying attention to your levels of hunger, eating until you feel satisfied and being able to listen to your body and stop eating.
Practicing this way of eating can greatly improve your gut health and optimise digestion, especially if you struggle with feeling sluggish or often suffer with digestive issues such as bloating and excess gas.
Optimising your gut health to support weight loss is greatly linked to supporting your gut microbiome. By improving your dietary and lifestyle choices and working on building healthier habits, you can create a better gut environment, which will therefore support your body in focusing on weight loss and improved metabolic health.
To get started on improving your chances of successful long term weight loss, reach out for support with one of our weight loss dietitians today. We can guide you to make personalised choices that are realistic and manageable, to ensure you are seeing changes and feeling your best.
