Fighting Fat with Science

Climate change and global warming are strongly linked to rising carbon dioxide or CO2 levels in the atmosphere, which partly come from burning fossil fuels. The world's politicians have agreed that a 2-degree Celsius rise in global temperature is as much as the world can take. Recent research, published in Nature, has revealed that many of our untapped fossil fuels with have to stay firmly underground if we are to avoid this 2-degree rise.

Researchers Cristophe McGlade and Paul Ekins from University College London explained the work to Kat Arney, also discussing the tough choices the world will have to make if we want to avoid the worst-case-scenario...

Cristophe -   This model looks out into the very long term up to 2100 and says, how can we best meet all of our energy needs in the future in a global context. It finds the cheapest way of satisfying all of the energy uses we might have in the future - how we're going to heat our buildings in the future, what we're going to use to drive our cars, how are we going to produce all of the industrial goods? For this work, what we did was we imposed this 2 degrees constraint on the model. So, we said that carbon emissions resulting from use of oil, from gas and from coal cannot result in a temperature rise which is above the 2 degrees target.

Kat - And so, when you look at this, how much can we use of the stuff we know is there in the Earth?

Cristophe - Of the coal reserves, only about 20% of these can be used. So, that means that 80% of current coal reserves have to stay in the ground if we don't want to exceed 2 degrees. For oil, it's about a third needs to stay in the ground and for gas, it's about half of what we think is currently economic to extract has to be left in the ground.

Kat - This seems pretty significant because obviously, there must be energy companies who have made predictions, who were going out looking for more oil and stuff in the ground. We talk about fracking, we talk about exploiting the oil that's under the Arctic. It's a bit difficult to say to them, "You know what guys, you can't even take the stuff that you think you've got."

Cristophe - Absolutely and there's a big inconsistency currently between what trajectory the world is currently on and what people have agreed to. So yes, the fossil fuel companies which are continuing to explore for new resources need to be aware that this is completely inconsistent with the 2 degrees target.

Kat - Oil and gas, and coal reserves that we have aren't equally distributed between all countries. So, how do some of the things shape up in terms of which countries have to be on the strictest carbon diet?

Cristophe - Generally, those regions which have the most resources currently are going to have to go on the biggest carbon diet, as you call it. For coal, the United States and Russia can only use less than 10% of their current reserves. In the Middle East alone, there's about 260 billion barrels of oil. That's the entire oil reserves of Saudi Arabia which needs to remain in the ground if we don't want to exceed this 2 degrees.

Kat - One of the things that comes out of your paper is that we can't even burn the resources that we know that we have and yet, companies are exploring in places like under the Arctic, we're looking at technologies like fracking which is very contentious at the moment. You're calculations would suggest that this is basically a waste of time.

Cristophe - Yes. So, within the model, we identify all of these different resources that are out there and you mentioned the Arctic. We can look at, under this 2 degrees scenario, which of these resources are actually used and the results suggest that actually, the Arctic oil and gas, and there might be quite a lot of oil and gas out there isn't required if we want to stay within 2 degrees. Some of the other sources you mentioned, you mentioned shale gas from fracking, there is some potential for that to be used particularly if we have a rapid reduction in coal consumption in the future, some gas will have to come through. And some of that gas can be shale gas. However, if countries such as the UK decide to develop its own shale gas resources, it has to be aware that as a result, someone else somewhere else isn't going to be able to use all of their reserves. So, there's always this trade-off between, if we exploit here, someone else has to not exploit somewhere else.

Paul - It's an enormous challenge because countries quite legitimately regard these resources as theirs and the decision whether they use them or not is their decision. They will need to agree not to use some resources somewhere. The countries that agree not to use their resources, they will probably wish to be compensated in some way. Those kinds of arrangements need to be on the table in the climate change negotiations.

Kat - Climate change is a global problem. It needs all the leaders of all the countries in the world to work together. Some countries say, "Well, no. we want to carry on. We want to develop. We want to use our resources." Is there hope realistically that countries can actually work together and come to these solutions. What's your personal feeling on this?

Paul - Yes, I'm very hopeful because I think increasingly, it will become obvious that climate change is something which they very much need to avoid. It may be true that money makes the world go round, but money doesn't go very far if you haven't got a liveable climate.

Kat - The projections in this paper go up to 2100. If you could maybe paint me a picture, perhaps over the next 20, 30, 40 years, how you would like see things changing?

Paul - Yes, things do change quite dramatically in the world in which we live over a period of two decades. So, I mean anyone who's more than about 40, if they look back 20 years, many of the things they now take for granted were not even dreamt of. It is my firm conviction that if we were to bite the bullet of low emission, energy systems and agriculture, by the time we got there and looked back, we wound wonder why we had thought it was going to be so painful. Because many of these technologies already exist, we can invest in them. A lot of them are not much more expensive than the technologies they're going to be replacing. So, my dream scenario is that both in the UK and globally, governments recognise the urgency of this issue and they start to do things like pricing carbon which will send investment in a quite different direction so that these low-carbon technologies become much more widely installed, emissions start to fall and publics become much more confident about the kind of trajectory that is possible.

The world is facing a medical crisis where bacteria are growing more and more resistant to antibiotics, while no new ones are being discovered. This could mean that we are eventually in a position where we can no longer treat once easily curable diseases.

This week, however, a new set of antibiotics have been announced by researchers in Northeastern University, which might revolutionise the field. Lead researcher Kim Lewis outlined the history of the problem to Chris...

Kim - The problem began about 40 or 50 years ago when it turned out that soil microorganisms that we could culture in our laboratories, to isolate antibiotics from, are very limited resource. They make about 1% of the total diversity of the microorganisms and the bulk of them are unculture'able: they will not grow in our lab. and so, in the absence of discovery and introduction of new antibiotics, our pathogens developed resistance and this resistance is now spreading faster than we can introduce new compounds.

Chris - Can we not just do some very clever chemistry and come up with new chemicals, try those and turn those into antibiotics?

Kim - Clever chemistry so far has largely not worked. The reason for that is that bacteria are very well protected. They don't want foreign molecules to penetrate into their cells. Antibiotics evolved over millions of years to reach the penetration barrier. We have not yet figured out how to do that with synthetic compounds.

Chris - Therefore, your approach is to say, "Well, given that we've only got antibiotics from the small minority of soil bacteria that will grow in our laboratory, what about the vast majority that won't? What kinds of chemicals could they be harbouring? Can we exploit them?"

Kim -   Exactly.

Chris - So, if they won't grow in your laboratory, how can you do that?

Kim - Well, then you do the exact opposite. We came up with a gadget that allows us to grow them in their national environment. And that's how we get access to uncultured bacteria.

Chris - Why won't these bugs grow in your laboratory normally? What stops them?

Kim - I do not have a complete answer to that question, but one thing that we did find is that at least some of uncultured bacteria depend on growth factors that come from their neighbours. You do not know where those growth factors are they're not going to start growing.

Chris - In other words, you need to recreate the environment that they would be in in the soil, more faithfully than a petri dish is capable of doing and that's why they won't grow at moment.

Kim - At least for quite a large number of cases, yes.

Chris - So, what does your gadget do to surmount that problem?

Kim - It's very simple. We take a sample of soil, dilute, mix with agar and then...

Chris - This is the stuff that cultured dishes contain - the growth medium?

Kim - Right. Instead of pouring it in a petri dish as you would normally do, we sandwich between two semi-permeable membranes that have pores, big enough for molecules to pass through but not big enough for bacterial cells. In a cell contraption, we call it a diffusion chamber, it then goes back into the soil where the sample originated from. This essentially tricks bacteria. They don't know that something happened to them. Everything diffuses through the chamber and they get all the growth factors that they need. They start growing and form colonies. Once a colony forms, that colony will then start growing on a petri dish in the lab. so, it looks like the main bottleneck in accessing uncultured bacteria is to get that initial growth into a colony.

Chris - Having done that, did you find some new molecules, some new compounds?

Kim - Yes. So far, 25 new antimicrobials were discovered and the compound that we're discussing today - teixobactin is the latest and probably the most exciting. The bacteria that it targets are called gram positive bacteria.

Chris - What effect does the teixobactin have when it hits these gram positive bugs like Staph aureus of which MRSA, the hospital superbug is a member, isn't it?

Kim - Yes.

Chris - What does it do to those bugs?

Kim - It targets a polymer that is needed to build the cell wall of bacteria. If you add this antibiotic, you see that the culture very rapidly lysis. It just clears.

Chris - How did you test it then?

Kim - We tested it in mice that are infected with Staph aureus, with a multidrug-resistant strain that is hard to kill. This compound, injected into a mouse cured it of a blood infection, of thigh infection, or of a lung infection with another pathogen that causes Streptococcus pneumonia.

Chris - Were the mice still healthy afterwards?

Kim - Yes.

Chris - So, it looks quite promising.

Kim - It looks quite promising and mice are not a bad predictor of how compounds will behave in humans.

Feeling full is our body's way of telling us we've had enough, and that maybe reaching for that last wafer thin mint isn't the best idea. But often this feeling doesn't kick in until we've already overindulged, especially when dieting. 

Researchers in London recently completely clinical trials of a new "secret ingredient", which can trick your body into thinking it has eaten more than it has by exploiting a system in place to avoid over-eating. Gary Frost from Imperial College London explained first to Kat Arney why we feel full when we overeat.

Gary - It's really complicated and we don't quite understand at the present time. there's lots of different signals that occur in the gut and just after you eat, some of these are generated by nerves. Some of these are generated by hormones.

Kat - What sort of things? They just signals to our brain going, "You know what? Put the fork down."

Gary - Absolutely right. they do exactly that. they send signals probably to specific areas of the brain, the hypothalamus and the brain stem. They tell your brain that you've had enough. But the brain can override that if it sees something that it really likes.

Kat - Tasty, tasty pie.

Gary - Absolutely right.

Kat - So, you're actually looking at how you can hijack this system to make us think that we are fuller and back away from the pie.  What did you start looking at?

Gary - Well, we've known for some time that deep down in your gut, in the colon, there are special molecules that are developed there by the bugs that live there. These molecules can actually signal and cause a release of appetite regulating hormones from your colon and it's that that we've been looking at, is that these very small fatty acid molecules that actually cause the release of these hormones that actually stop you eating.

Kat - So, it's food getting to the bugs in our gut that then make this signal and stop me from eating.

Gary - That's correct. That's absolutely right. but unfortunately, where we currently live, the actual types of food, because these are dietary fibres, the amount that we need to actually do that, we just can't eat enough at the present time. it was different if you live in Africa or somewhere where you have a very traditional native diet. But in the western world, we don't eat close to enough to actually do that.

Kat - Tell me about how you're trying to hack this system, how you're trying to use these chemicals to make a way of making people feel fuller.

Gary - It takes a bit of clever technology which has been developed by our research partners in Glasgow where we take those molecules - so short chain fatty acids and we attach them to a dietary fibre. So, a dietary fibre can't actually be broken down by the enzymes in your small bowel. So, what it does, it means that the actual short chain fatty acids hitch a ride on the dietary fibre and they get all the way down into your large bowel, into the colon where the bugs then actually chomp up the dietary fibre and release the short chain fatty acid. That actually enhances the amount that's there and releases the actual hormone that actually reduces your appetite.

Kat - So, the idea is you could add this to food say, a pie, if you put this in with the pie filling then your pie would make you feel a lot fuller and you wouldn't want to eat so much of it.

Gary - Well, you seem to be a bit stuck on pies but generally, the idea that this has been developed as a food ingredient because obviously, what we want to try and do, because as you've just heard, weight gain in adults is so widespread, you've got to develop systems that are on a population basis. So, this is an attempt to do exactly that. it's to develop a very safe food ingredient that will suppress appetite in people who are actually concerned about weight gain.

Kat - It does sound great, but where is this at the moment? Have you tested it in clinical trials? Are there any risks for example like, could you overdose on it?

Gary - Well, the paper that we released just before Christmas - all the testing was done in humans. So, we know  that this works. That we see a reduction in weight gain over a 6 months period when humans are given this particular molecule. can you overdose? It's like any dietary fibre. If you eat too much of it too quickly then you're going to get minor effects such as bloating. But if you're actually sensible about what you do, it has very, very few side effects.

Kat - Very briefly, have you actually tried it yourself?

Gary - Yes. We've tried it ourselves in the clinic as part of the volunteers and it does what it says really. It actually causes a short term suppression of appetite. So, you eat it and about 3 hours after you've eaten it, you feel more full.

It's that time of year when everyone is struggling with their hastily made resolutions, but why is giving something up so much hard work? The Food and Brand Lab in Cornell University look at the psychology of food and dieting to understand better the way we think about eating. Graihagh Jackson spoke to researcher Aner Tal to find out if they have discovered any tricks of the mind to help people give up their vices. 

Aner - So, the trick is trying to control the environment rather than to control yourself because to control the environment, it takes decisions that are less on an ongoing basis. So, it'll be less demanding. If I keep trying to control myself in an environment where it's difficult to do so, that will take a lot of will power and at some point, I'll run out and slip. On the other hand, if I make a one-time conscious effort to change my environment, because we tend to respond automatically to food and a lot of our eating behaviour is not necessarily conscious. So, I see the cake. Even if I tell myself, "Don't eat the cake" that's because the initial inclination is, this is something I would really enjoy. So, I'm sort of programmed to go and eat it and I need to tell myself no, and it's an active action to override the initial inclination to eat the cake. So, what I want to do is I want to remove some of those triggers for unhealthy eating. So, that can be done by making, eating healthy foods easier, more convenient and making eating unhealthy foods more difficult, making the foods less visible and if possible, making them less appealing. So, I'll give some concrete examples for that. I have an insane ice cream addiction. I can't get enough. Like if there's 5 pints of ice cream in my fridge...

Graihagh - It would be gone by tomorrow.

Aner - Yeah, that's definitely possible. And that's kind of bad for weight control. So for instance, I could have ice cream in my freezer, but keep it in the back so that I can't see it every time I open and then I'm less inclined to - because once I see a stimuli, I'm going to react to it. if it's not visible then I'm going to need to think about it independently and then get it. that might sound like it wouldn't make a huge difference but it would at least for some people.

Graihagh - Hide the food in the back of your cupboard then, check, but what about when you're not at home? For example, eating in a fancy restaurant.

Aner - When I used to go out for dinners with my family to a restaurant, my mum would always tell me, "Don't eat. We're going out to dinner." But sometimes it might actually be a good idea to eat something to make yourself a bit less hungry so you're not going to go wild once you're exposed to all these temptations. And also, part of what happens automatically is, if a food is in front of us, we tend to continue eating it. and that's something we've seen in a broad variety of studies. So, there's a classic study that a director of the food and brand lab did where we had soup bowls constantly refilling themselves through tubes as people ate. And people ate a lot more when the soup bowls continuously refilled themselves because there's food in front of you and you continue eating and the plate doesn't go empty, so you don't know that you're done.

Graihagh - Just like a bottomless pit of soup.

Aner - Yeah, exactly.

Graihagh - How much soup did these people eat?

Aner - That, I have to check. So, this and a lot of the other information, if you want to get actual numbers, are on our website at Food and Brand Lab. if you Google Food and Brand Lab, you can easily get it.

Graihagh - I did have a look on the website as Aner suggested. People unwittingly ate 73% more soup when they didn't notice their bowl was being refilled compared with people who knew just how much they were eating. What's more is that they reported feeling just as hungry. So, feeling full can simply come down to paying attention to how much you're eating. This idea of avoiding mindless eating came up again.

Aner - One of the studies we recently had published had to do with television viewing and how, if someone watches a TV programme that's more engaging to them, they wind up eating more. Part of that relies on mindless eating. So, the food is right in front of you. You're more distracted so you're going to eat mindlessly to a greater extent. You're paying less attention and you're just eating on autopilot. Eating is very easy. It's something that you don't really need to think of. You just do it automatically. So, making it more difficult for ourselves to eat mindlessly is one trick that people can use to control their eating. And also, changing what you eat mindlessly by changing what's available.

Graihagh - There you have it. hide the ice cream, display the celery and pay attention to everything you eat. And whatever you do, don't eat from a bottomless bowl of soup or in my case, custards.

Michael Mosley, Giles Yeo and Lucy Cheke return to answer some audience questions sent in from social media about various aspects of dieting. Chris Smith started by talking to Michael about the sedentary world we seem to live in...

Michael -   The environment that we have created is one where all the inducements are to sit down, not to be active, basically, not to move very much. This is not only true of the offices we are in, but also, just getting to the office. If you want to get up to the 7th floor at the BBC where I work, the great incentive is to take the lift because the lift is right there in front of you. If you want to go up the stairs, you have to kind of work your way around the back. I think what we should be doing is making it much harder to take lifts. I think we should do things like slow them down or perhaps put the smell of urine in the lift to discourage people from taking it. I was recently in a hotel in Sweden and there, they had this lovely stairs beckoning you and right around the back was the horrible little lift whereas in most hotels, it's the other way around. That when you actually try and find the stairs, either they are locked or they just smell really horrible.

Chris - Yes, so we need to do the sort of the multi-storey effect and make the lift unappetising. Now, one diet that's been very popular in certainly recent months is this so-called 5-2 diet. We've had some questions in about this. What actually is the 5-2 diet? How does that work?

Michael - So, the 5-2 diet is intermittent fasting. The idea is that instead of being on a low calorie diet for weeks, months on end, that what you do is you eat normally 5 days a week and then 2 days a week, you cut your calories quite dramatically, down to about quarter of the normal level. So, that would be about 500 calories for a woman, 600 for a man. And there appeared to be health benefits which go beyond losing weight, because by doing so it generates a level of stress rather like when you go for a run, you get stressed. Some forms of stress are rather good for you.

Chris - A note here from Carol. She said, "Is it normal to get headaches on those fasting days?" I must admit that on days when I've gone without food and I'm accustomed to eating usually quite a lot she says she gets symptoms and I certainly concur with that.

Michael - I think the main thing you need to do to avoid headaches is drink lots of water because we get a lot of water via the food we eat. And therefore, if you're cutting down on the amount of food you're eating then you just need more water. More water is great from all sorts of perspectives. You'll burn a few calories, just to warm it up and also, it will encourage you to go to the loo a bit more and that means getting up, getting active and things like that. But there's no intrinsic reason why it should lead to headaches. Indeed, if it happens, it should be transitory, it should pass, but headache is normally associated with dehydration.

Chris - Question here for you here Lucy. Why is it so hard to keep those resolutions that we resolutely make every year and then resolutely break?

Lucy - It's very hard to empathise with your future self. Your future self is a very different person from your current self and it's quite easy to think just as I would think, "Oh well! It's perfectly fine for Chris to give up all his food but I'm not sure if I'm willing to do that." it's quite easy to make those kinds of decisions for our future selves as well. So, we tend to - on the first hand - make New Year's resolutions that are quite unrealistic. We are quite harsh on our future selves.

Chris - Not just because we're drunk at that time.

Lucy - Well, obviously partly because we're drunk at that time, but we tend to be quite kind to our present selves and quite harsh to our future selves. So, we make resolutions that are quite difficult to keep. On the other hand, it's also this tendency to think that we're going to be better in the future. We tend to have an idea of our future selves that they are going to fulfil all the things that we currently don't think that we can do. And therefore, we put restrictions on them and say, "Okay, I decide to do it now, then I definitely will do it in the future." But what's needed to be done is to realistically say, "Future me is not actually that different to current me. Current me is kind of lazy, so future me is going to be going to be quite lazy too."

Chris - Giles, we've got this message here from Stella who says, "How is weight loss affected by how big you already are?"

Giles - That's a very interesting question. I think the largest thing about how big one is is that the bigger you are, oddly enough, the more energy you need - that's not odd. But therefore, the more energy you burn. The smaller you are, the less energy you eat, that you need and the less energy you actually burn as well. So, your size will determine actually your metabolic rate. So, that obviously then has a big role to play in how you would then react to cutting specific amounts of calories.

Chris -   Michael, we've got this Tweet here from Iqra who says, "Is eating late at night bad for you or does it just matter what the aggregate number of calories across the day that you consume is?"

Michael - I think broadly speaking, the most important thing is the amount of calories you eat across the day, but there is some evidence that eating late at night is not a good thing to do because actually, what you need is a period of time when you're not eating. That's when a lot of repair goes on. so, if you eat late at night and then get up bright and early and start eating again, you're not giving your body some rest from food. The old idea that we should eat lots, small meals regularly is probably a profoundly bad idea.

Chris - So, this whole question of breakfast like a king, lunch like a prince, dine like a pauper, that's based on sound principles then.

Michael - It's not a bad idea at all and there is some evidence, I've seen a couple of trials which suggest that eating calories in the morning is probably better for you than eating a lot later in the day.

Chris - Giles, Alex Johnston has tweeted @nakedscientists, what is your view of rapid versus slow weight loss? Which is probably more effective do you think?

Giles - I think the whole point about weight loss is not the actual weight loss. I think most of us can actually lose the weight. It's keeping the weight off. So, losing it in a quick way, maybe it's more unsustainable compared to actually doing it in a slow methodical fashion that is then possibly more easy to maintain because it's keeping the weight off that is actually the key challenge rather than losing the weight itself.