You may think you have a healthy diet — scraping low-fat spread on your toast and tucking into carrots and peas with your dinner.
But if you’re not nourishing the vast population of bugs in your gut, you could be steadily putting on weight around your middle and becoming at risk of developing type 2 diabetes.
The ‘microbiome’, the trillions of microbes inside your digestive tract, play a key role in healthy ageing, protecting against inflammation and a plethora of life-shortening diseases — and science is beginning to show that they play a part in controlling whether you gain or lose weight.
These microbes, made up largely of bacteria and fungi, take the food we eat and convert it into hormones, vitamins and chemicals, many of which are vital for longevity and health.
All this week in the Mail I’ve been highlighting some of the sometimes surprising reasons why our obesity levels are rising and revealing the small lifestyle changes you can make to reduce the risk of developing type 2 diabetes.
You may think you have a healthy diet — scraping low-fat spread on your toast and tucking into carrots and peas with your dinner. But if you’re not nourishing the vast population of bugs in your gut, you could be steadily putting on weight around your middle and becoming at risk of developing type 2 diabetes, writes Dr Michael Mosley
Today, my focus is on gut bacteria. A few years ago I did an experiment to see how bad a diet of processed food can be, and spent four weeks eating processed meat once or twice a day. I’d have bacon for breakfast, a salad for lunch and a burger for my evening meal, or a sausage for breakfast and a salami sandwich for lunch.
After a month a health check revealed I’d gained 3kg — much of it around my gut.
This was bad news because fat around your abdomen greatly increases your risk of becoming insulin-resistant and diabetic. My blood pressure had also shot up.
But perhaps the most surprising changes had gone on, unnoticed, inside my gut. Stool samples, taken before and after four weeks, showed some pretty big changes to my gut bacteria population.
My microbe diversity score (one of the better measures of gut health) had fallen from 7.27 to 7.1 (ten is the most diverse). This doesn’t sound much but it meant that where I’d previously had a diverse microbiome (I was in the top 30 per cent), I had dropped to the bottom 30 per cent.
There was also a major shift in my gut bacteria in favour of one type called Firmicutes, linked to obesity and inflammation.
Thankfully, after reverting to my normal diet my weight, blood pressure and microbiome gradually returned to normal.
It’s striking how bad processed food is for your microbiome. One reason is the amount of sugar and fat it contains, and there are emulsifiers, which are added to make it taste better.
In experiments where common emulsifiers were fed to mice, researchers found this encouraged the growth of bacteria that attack the gut’s mucous lining. This leads to inflammation, which contributes to the development of diseases such as type 2 diabetes and obesity.
Another problem is that many of us eat a narrow range of foods. This means our gut bacteria must exist on a restricted diet.
Three-quarters of the world’s food comes from just 12 plants and five animal species. The more limited your food, the more limited your bacterial diversity.
But how does this make us gain weight? We depend on gut bacteria to do some digesting. Some, like Firmicutes, are better at extracting energy from the food we eat than others. This means that if I have more Firmicutes in my gut than my wife (which I do), I will absorb more calories than she does from the same meal.
Other microbes in the gut influence how much your blood sugar levels rise when you eat, as well as how and where fat is stored. Research published by the University of Alabama in the U.S. has identified fungi in the intestine that are sensitive to what we eat. Researchers showed that mice fed a processed diet of purified carbohydrates grew fungal communities, which led to excess fat in the liver and weight gain.
Worryingly, it seems some members of your microbiome can influence your mood and the food choices you make — so if you have a lot of junk-food-loving bugs, they will clamour for more junk food when their supply runs low, triggering cravings.
Thankfully, studies have shown that what you eat can reinforce and support the armies of ‘good’ bacteria and starve out the ‘bad’ bacteria.
It’s a good idea to avoid sugar, artificial sweeteners, refined carbohydrates, processed foods and sweeteners, and to expand your repertoire of nutrient-rich foods.
Foods such as nuts, seeds, olive oil and vegetables such as garlic and onions are packed with chemicals the ‘good’ microbes love. Fermented foods such as kefir and sauerkraut have microbes that help your gut thrive.
Eating more of the right foods and less processed food is the best way to support the ‘good guys’.
Here, I share some recipes that will help you in your quest to pack your plate with the widest variety of vegetables to encourage the diverse microbiome population that will protect your health.
CHICKEN TIKKA MASALA
A healthy version of a favourite curry, which is much better than a takeaway. Choose a good-quality tikka curry paste
Per serving: 427 cals
Protein 46g, Fat 21g, Fibre 4g, Carbs 11.5g
A healthy version of a favourite curry, which is much better than a takeaway. Choose a good-quality tikka curry paste. Serve with steamed greens or cauliflower rice or, if you are not aiming to stick to 800 calories a day, add 2-3 tablespoons of brown rice or wholemeal roti.
- 1 tbsp tikka curry paste
- 4 tbsp full-fat live Greek yoghurt
- 2 boneless, skinless chicken breasts (about 350g), cut into roughly 3cm chunks
- 1 tbsp coconut or rapeseed oil
- Fresh coriander, to serve (optional)
- ½ red chilli, sliced, to serve (optional)
For the masala sauce
- 1 tbsp coconut or rapeseed oil
- 1 medium onion, peeled and finely chopped
- 2 garlic cloves, peeled and crushed
- 15g fresh root ginger, peeled and finely grated
- 2 tbsp tikka curry paste
- 1 tbsp tomato puree
Combine the curry paste, yoghurt and two generous pinches of sea salt in a bowl. Add the chicken and mix until well coated. Cover and leave to marinate in the fridge for at least an hour, preferably longer or even overnight.
Fifteen minutes before you are ready to serve, make the sauce. Heat the oil in a large non-stick saucepan over a medium heat.
Add the onion and fry gently for 5 minutes, or until softened, then stir in the garlic, ginger and curry paste and cook for 1½ minutes more.
Pour 300ml water into the pan, stir in the tomato puree and bring to a simmer. Cook for 5 minutes, then remove the pan from the heat and use a hand blender to blitz the sauce. Set aside.
Heat the remaining oil in a large non-stick frying pan over a medium-high heat and fry the marinated chicken for 3 minutes, or until lightly browned, turning regularly.
Add the prepared sauce to the pan and bring to a simmer. Cook for 3-4 minutes, or until the chicken is thoroughly cooked, stirring constantly. Add a splash of water if the sauce thickens too much.
Sprinkle with the chopped coriander and chilli, if using, before serving.
- If you don’t have a stick blender, you can leave out the blitzing but the sauce won’t be as smooth and creamy.
PRAWN COURGETTI AND SPAGHETTI WITH CHILLI AND LEMON
Love Your Gut Cook’s Tip: You can use raw prawns but you need to cook them for 1-2 minutes before adding the chilli and garlic. They are done when pink and hot
Per serving: 271 cals
Protein 21.5g, Carbs 16g, Fat 12.5g, Fibre 4g
Love Your Gut Cook’s Tip: You can use raw prawns but you need to cook them for 1-2 minutes before adding the chilli and garlic. They are done when pink and hot.
- 40g dried wholewheat spaghetti
- 1 large courgette, trimmed and spiralized or peeled into ribbons, or use a pack of courgetti
- 2 tbsp extra-virgin olive oil
- 200g cooked, peeled prawns, thawed if frozen and drained
- 2 garlic cloves, peeled and crushed or finely grated
- 1–1½ tsp crushed dried chilli flakes
- 1 small lemon, finely grated zest and juice
Half fill a large pan with water and bring to the boil. Add the pasta and cook according to the pack instructions. Stir in the courgetti for the last 15 to 20 seconds of the cooking time. Drain the pasta and courgetti in a colander and set aside.
Meanwhile, heat the oil in a large pan, add the prawns, garlic and chilli, and fry over a medium heat for about 2 minutes, or until heated through, stirring regularly. Don’t overcook the prawns or they will toughen.
Add the spaghetti and courgetti, lemon zest and juice to the pan. Toss together, season with salt and black pepper and serve in warmed bowls.
CREAMY CASHEW AND SQUASH CURRY
A vegetable curry packed with golden vegetables and cashews. Serve with leafy green veg and perhaps some cauliflower rice
Per serving: 598 cals
Protein 20g, Fat 43.5g, Fibre 10.5g, Carbs 26g
A vegetable curry packed with golden vegetables and cashews. Serve with leafy green veg and perhaps some cauliflower rice. If you like more heat, stir in ½-1 tsp crushed dried chilli flakes for the last 5 minutes of the cooking time.
- 1 tbsp olive, coconut or rapeseed oil
- 1 large onion, peeled and chopped
- 100g plain cashews
- 2 large garlic cloves, peeled and finely chopped
- 3 tbsp medium Indian curry paste
- 300g butternut squash, peeled and cut into 2.5cm chunks
- 3 medium carrots, well washed, trimmed and cut into 2.5cm chunks
- 1×400ml can full-fat coconut milk
- 2 peppers, any colour, deseeded and sliced
- Small handful roughly chopped coriander leaves, to serve (optional)
Heat the oil in a large saucepan, add the onion and nuts and fry over a medium heat for 5 minutes, or until the onion is softened, stirring regularly.
Add the garlic and curry paste and cook for 1 minute, stirring constantly.
Add the squash and carrots, pour over the coconut milk and refill the can with water. Pour this water into the pan and stir well. Cover with a lid, bring to a gentle simmer and cook for about 25 minutes, or until the vegetables are almost tender, stirring occasionally.
Add the peppers, return to a simmer and cook, uncovered, for a further 5 minutes, stirring once or twice.
Season with salt and ground black pepper and scatter with coriander, if using, to serve.
FASTEST SPAGHETTI BOLOGNESE
A brilliantly versatile and quick-to-prepare Bolognese. Made with turkey, rather than beef mince
Per serving: 426 cals
Protein 57g, Carbs 23g, Fat 11g Fibre 5.5g
A brilliantly versatile and quick-to-prepare Bolognese. Made with turkey, rather than beef mince, it can be adapted for all sorts of dishes and freezes well.
- 2 tbsp olive oil
- 1 medium onion, peeled and finely chopped
- 200g small mushrooms, quartered
- 500g turkey breast mince
- 1 × 400g can chopped tomatoes
- 2 tbsp tomato puree
- 1 chicken stock cube
- 1 tsp dried oregano
- 20g Parmesan, finely grated
For the spaghetti
- 80g wholewheat spaghetti
- 2 large courgettes, spiralized, or use a pack of courgetti
Heat the oil in a large non-stick frying or sauté pan, add the onion and mushrooms and fry over a medium high heat for 5 minutes, stirring often.
Add the turkey mince and fry for 5-8 minutes until lightly browned.
Meanwhile, cook the spaghetti in a large pan of boiling water for 10-12 minutes, or according to the pack instructions.
Tip the tomatoes into the pan with the mince, stir in 400ml water, the tomato puree, crumbled stock cube and oregano. Bring to a simmer and cook for 5-10 minutes, stirring regularly, until thick.
Season with salt and ground black pepper. Add the courgette ribbons to the pan with the pasta and cook for 30 seconds more. Drain and divide between four bowls.
Top with the Bolognese, sprinkle over Parmesan and serve with salad leaves.