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We know that diet changes the biome easily and quickly - but of course the key is knowing what you want to change it to and how! The Israeli team think that avoiding foods that currently give you 'sugar spikes' can change it in a beneficial way - but you'd need to be profiled by them to find out what those foods are. At the moment that's not easily possible, unless you live in Israel and are ready to sign up for their research. They are hoping to make it widely available, though (and not for profit, I believe)

At the moment, the Israeli team are only recruiting people within Israel. There are places you can have your gut microbes tested, but you wouldn't get the same interpretation as you'd get from their project. Have a look at our website for more details.

Yes - there are genetic collagen mutations that can affect ligaments, and probably others that I don't know about!

If you've got any questions about tonight's episode - or the rest of the series, then now is the time to ask! We'll be here for another 20 mins doing our best to catch them all from Twitter. Just use #trustmeimadoctor , external

This iWonder guide reveals some easy tips on how to fit exercise and healthy eating into a busy day.

The evidence around doing things socially rather than on your own is mounting. In our own experiment the co-operators improved by 16% and the competitors by 30%, but that masked a lot of variation in individuals and over the weeks.

Research in the US by Dr Damon Centola is beginning to reveal that a combination of co-operation and competition might be the secret to the best results. 

You can sign up online to join in with programmes such as the Workplace Challenge that harness these psychological findings to help you get more active. 

There are links to the research and the Workplace Challenge on our website.

Paracetamol is thought to be useful for headaches, toothache, and reducing fever – and its action can be enhanced by taking it with caffeine. Read more on our web page.

We have previously reported on the potential for long-term, high-level use of paracetamol, so if you have chronic back pain, then you may wish to talk to your doctor about alternatives.

We were pretty taken aback by the difference that putting your scales on a solid surface versus the carpet actually made. Online there are more claims that scales on a carpet over-estimate weight, whilst our consistently under-estimated, by about 10kg! It seems that that's because the little rubber sensors in the feet sink into the carpet to such an extent that the carpet ends up supporting the plastic frame of the scales we were using - hence taking some of the pressure off the sensors. You can watch the film again below and on our website.

Or should we all be doing the 4-5 hours of cycling a weekend plus a couple of sessions during the week that Prof Lucia recommends? Watch his interview again below and also on our website.

So, can over-doing it damage your heart? Here's that interview with Prof Sharma again...

An inactive lifestyle can lead to many health problems like diabetes, osteoporosis, stroke and heart disease. 

But beyond that exercise may even help keep us younger and more alert. 

It is even an antidepressant.

Exercise also reduces the risk of some cancers.

For more about how British running is booming and whether there is such a thing as doing too much exercise, check out this Newsbeat article.

Image source, Thinkstock

Image source, PA

A record total of 247,069 people entered the ballot for the 2016 London Marathon in April. 

Last year the oldest runner was 90 (!) and this year even astronaut Tim Peake will be running the London marathon from the International Space Station. 

We sure love marathons in the UK. (Although, ahem, we are the second slowest nation in Europe just ahead of Greece). 

Are marathons a health boon or can they be dangerous?

Image source, Bob Martin / Virgin Money London Marathon

Image source, Skeeze/Pizabay

Running outdoors uses more energy than running on a treadmill because of wind resistance: so on a treadmill you need to set it to a 1% gradient to compensate. 

When running outdoors people tend to run faster than those on a treadmill without realising it. That's probably because on a treadmill your eyes aren't getting the cue from the moving scenery so you find it difficult to judge speed. 

On a treadmill, although there are fewer hazards to cause injury, and the belt is shock-absorbing, because every step is exactly the same, people are more prone to overuse injuries. 

So again, use varied inclines and speeds if you're running indoors. Outdoors, the varied terrain helps strengthen ligaments and improve your balance. 

Outdoors runners get the added benefits of lowered blood pressure, better mental health and - during the summer - the UV light in sunshine triggers vitamin D production.

For every mile you run your feet will hit the ground about 1,000 times. Repeating the same movement puts you at greater risk of joint or ligament damage. So if you use a treadmill it's a good idea to mix it up a bit by varying the speed and the incline. 

As for Michael, as he explains in this BBC Magazine article, outdoor running has clear advantages: It's far more varied and he can take his dog out with him. 

A study found that in general people who exercise outdoors claimed to enjoy it more, find it more satisfying and say they are more likely to do it again...whether they actually do remains to be seen!

Image source, iStock

The research in Israel is pretty revolutionary. 

Here's two more clips in which Dr Eran Elinav and Prof Eran Segal talk more about their work and its implications, and there are more details on our website too.

Read more about Saleyha's experience in Israel - and why she can now eat ice-cream guilt free ! - in her BBC Magazine article.

Image source, SilviaEmilie/Pixabay

Timely reminders and prompts at the point of decision can really help us to remember our priorities and shop more healthily. For more on the results of our experiment on food shopping see this article on our web page.

Here are those key findings from Dr Brian Wansink at Cornell University again:

• Store all food out of sight, apart from fruit. Research has found that those who keep foods like cookies, crisps, sweets and even cereal on their kitchen counters are more likely to be overweight. Keeping unhealthy snacks out of sight is the best way to ensure that they stay out of mind.
• Rearrange your cupboards to put healthier options first. When we open our cupboards we’re three times more likely to grab the first thing that we see than the fifth one. So when you’re unpacking your shopping make sure you put healthy foods first. Likewise make vegetables more visible in the fridge by moving them out of the bottom drawer and into your eyeline.
• Avoid distractions when eating – if we’re reading, working or watching TV we’ll just keep on eating without realising it.
• Leave serving dishes in the kitchen rather than bringing them to the dining table – we’re so lazy that if we have to get up and walk to get seconds we’re much less likely to do so! In fact this single change could help us to eat 20% less at dinner.