‘Fat but fit’ – Lessons in the language of a press release

This week a paper from the EPIC-CVD which I co-authored was published in the European Heart Journal. Unfortunately the article was subsequently promoted in the press with the headline ‘Fat but fit’ still risk heart disease, encouraging a belief that physical activity offers no heart health benefit to those that are overweight.

This headline is misleading because most people understand ‘fit’ to mean physically activity, however the paper didn’t measure physical fitness. Instead it measured metabolic health (ie, high blood pressure, cholesterol and blood glucose) which some term ‘medical fitness’, and is often shortened to ‘fitness’. Hence the confusion.

What the paper really shows is that being overweight and having poor metabolic health both contribute to increasing risk of coronary heart disease (CHD), or a heart attack, to put it more simply. If you group people based on their weight status and metabolic health then the risk of having a heart attack increases in the following order:

 

 

 

 

 

 

To provide some context to these numbers, we know that having a heart attack is more common in older people – that risk increases with age by about 10% per year. Being overweight and healthy notionally makes you 2 ½ years older (in terms of heart disease risk) than a normal weight and healthy person. Whilst being obese and unhealthy notionally makes you 15 ½ years older!

My take home message from these figures is that having poor metabolic health is much worse than being overweight or obese on its own; however people carrying excess weight still don’t get off scot-free. So, if you can improve your metabolic health (whether you are normal weight or overweight or obese) you can substantially reduce your risk of CHD. Equally if you can reduce your weight (whether you have good or bad metabolic health) you can reduce the likelihood of a heart attack even further.

What about being fit, ‘physically active’ fit?  

If you are overweight and are physically active then this will more than likely be good for your health – we know that physical activity has beneficial effects on metabolic health. The long-standing fat-fit hypothesis states that the health benefits of being physically active can cancel out the increased risk of being overweight, so it’s possible to live just as long if you are fat as long as you are fit. Does our work say anything about that idea? Not really, not without a lot of inference and assumptions. You’d need a study of physical fitness and weight and metabolic health to get to the bottom of that one (a study like this).

What is apparent from this analysis is that grouping people based on continuous measures of health is spurious. If you look at the ‘apparently healthy’ overweight or obese group you’ll see that their blood pressure, cholesterol, blood glucose, etc are actually still higher than the supposedly equally healthy normal weight group. To me this suggests that metabolically healthy obesity doesn’t really exist, not long-term. The people in the healthy obese group just didn’t quite meet the cut-offs for being defined as ‘unhealthy’ yet, suggesting it’s only a matter of time before they cross over to the unhealthy group.

So what’s the point of putting people in boxes, we are all individuals after all, with our own unique profile of risk factors. I’d say let’s try and keep continuous risk factors continuous and aim for lowering them across the whole range using whatever methods have been shown to work in the past. Physical activity and diet can both help in different ways, to either improve metabolic health or promote weight loss, so aiming for a healthier lifestyle is as important as it ever was.

This blog was written by Dr Laura Johnson, a Lecturer in Public Health Nutrition in the Centre for Exercise, Nutrition and Health Science, School for Policy Studies.

 

 

 

Back to school for MyHeart Beat

Dr Laura Johnson, is a Nutritional Epidemiologist and Senior Lecturer in Public Health Nutrition. Her research focuses on establishing the role of overall dietary and eating patterns in the prevention and treatment of obesity, diabetes and coronary heart disease as well as understanding the factors that influence food intake and appetite control. In this blog, she reflects on a recent visit to Malaysia to research adolescent lifestyle in conjunction with the MyHeart Beat project.

In April, this year I went back to school, some things were just the same as I remembered but others were very different, mainly because I was in school in Malaysia. I had found myself in Kuala Lumpur for work and I was visiting schools to find out exactly how big a task we had taken on for our new collaborative research project MyHeart Beat (Malaysian Health and Adolescents longitudinal Research Team Behavioural Epidemiology and Trial).

MyHeart Beat is funded by the UK Medical Research Council and Academy of Sciences Malaysia (Newton Ungku Omar Fund). The project aims to explore how changes to diet and physical activity could improve heart health in Malaysian adolescents. It’s a collaboration between researchers in the University of Bristol’s Centre for Exercise, Nutrition and Health Sciences and the University of Malaya’s Faculty of Medicine. Our aim is to find ways for Malaysian teens to be more active and eat better, which will help them in the future to avoid obesity, type 2 diabetes, and cardiovascular disease, chronic conditions that are affecting ever increasing numbers of people in Malaysia.

MyHeart Beat builds on MyHearts (Malaysian Health and Adolescents longitudinal Research Team study) an excellent project by researchers at the University of Malaya, in collaboration with researchers from Queen’s University of Belfast, who have spent the last 5 years following more than 1000 teenagers from the age of 13 to 17 years in 3 Malaysian states. MyHearts has collected detailed information on diet, activity, lifestyle and health and has shown that 15% of adolescents are overweight and a further 9% are obese. Physical inactivity is rife (64% of teens are inactive) and breakfast habits are erratic (25% of teens never or only occasionally eat breakfast). We’re planning more analyses of this rich data to find out about the patterns of behaviour related to obesity and heart health.

I’ve previously explored patterns of food intake associated with obesity and shown that it’s a combination of high-fat, low fibre and energy density that is important rather than any single aspect of diet. Key foods part of an obesogenic dietary pattern in the UK include fruits, vegetables, and high-fibre bread (not eating enough of them) and white bread, crisps, sweets, and processed meat (eating too much of them). We expect the most common foods eaten in Malaysia to be different to the UK but in principle whatever foods there that make a diet energy dense, low in fibre and high in fat are still likely to be those most important for preventing obesity. In MyHeart Beat we will apply the same method for finding patterns of behaviour (reduced rank regression, RRR). RRR is a statistical technique that, for dietary patterns, adds up intakes of all foods after giving some foods more emphasis than other (by giving pattern loadings). RRR works out how much emphasis to give different foods by trying lots of options until it settles on the one where foods are combined in such a way that the energy density, fibre and fat content of the whole diet can be predicted best. You end up with pattern loadings (numbers) for each food and the larger the loading the more important that food is for predicting the obesogenic features of diet. Using the loadings, it’s then possible to rank foods in order of importance and identify exactly what foods to change to make diets less likely to lead to obesity. With our analyses, we hope to find out not only what the most important foods are but also what activities are best for maintaining health throughout adolescence. Once we know what the high-risk behaviours are we can start working out ways to help teenagers to change.

Although, even when you know what to change you then have the task of working out how to change it. There are many different routes we can take to change behaviour; the sheer number of options can be challenging but is also what makes the project fascinating. The MyHeart Beat team has lots of experience trying to change behaviour in children in the UK, Europe and Malaysia. For changing diet we’ve attempted intensive programs led by dietitians as well as computer based courses supervised by teachers. Innovative strategies we’ve tried for increasing physical activity have included after school clubs led by teaching assistants; dance workshops and harnessing the power of social networks to spread positive physical activity messages. In Malaysia, the MyBFF@school program (My Body is Fit and Fabulous) has been designed specifically to help overweight and obese adolescents control their weight and provides a valuable platform on which to build a broader program that could help all adolescents stay healthy.

A starting point for designing an intervention is simple logistics. What is even possible to change within Malaysian schools? So that’s what brought me to Kuala Lumpur, to visit schools and see for myself how life works for adolescents at school over there. I realised that the biggest difference compared with my school in the UK was the timing. In Malaysia, school starts at 7 am and ends at 1 pm, break time is for 20 minutes between 0930-1030 (depending on which year you are in) and this is the time when the cafeteria is open for hot meals and cold drinks.

The school canteen offers lots of fried and sweet snacks like burgers, sausages, chicken and samosas, not so different to school food I remember. But more traditional meals, made of rice, noodles, eggs, fish or meat with sauce, were also for sale.

Some schools had fruit snacks suggesting it may be possible to alter the range of foods available. There were vats of ice-cold drinks like fruit squash and Milo and iced tea, all sugar-sweetened. Water wasn’t freely accessible but water bottles were sometimes brought in from home.

Touring the rest of the school, I saw that there were plenty of spaces for physical activity, a school gym, hall, basketball courts and a playing field. But the heat was high as was the humidity, I was sweating just standing still! I had no desire to be physically active in those conditions, which made me wonder what the kids thought about that.    

That leads me back to what MyHeart Beat aims to do in the next 18 months. We plan to find out what staff and students think about different options for changing diet and activities – because ultimately it’s the people whose behaviour you are trying to change that know best what will work for them. We’re also aware of some local initiatives by state nutrition divisions starting this year to make improvements to the school food supply e.g. in Perak, parents/teachers are asked to report if the canteen is selling unhealthy food. To find out more about what the adolescents, teachers and Ministry of Education officials think about what can and should change, we’re planning some interviews and focus groups to ask them directly. From this we’ll work out the options that will be most feasible for changing. Then we’ll develop an intervention (set of changes) that we hope will improve diet and physical activity and ultimately cardiovascular and metabolic health. Our approach follows the UK Medical Research Council (MRC) recommendations for designing interventions. We hope that by building on a strong evidence base and crucially talking to the local people, we’ll ensure the intervention we design will be a success.

Towards the end of 2018 we’ll be taking our intervention out to some schools to test it out. This small pilot project is the ultimate aim of all of the different parts of the project and will tell us if the plans we’ve made will work in practice. I’m looking forward to visiting Malaysia again at that stage, and getting some more fabulous hospitality from the MyHeart Beat researchers over there!

To Shooka, Shafina and Fadzrel, Terima Kasih (Thank You) for having me.

 

 

 

Can after-school dance increase physical activity levels in adolescent girls?

Russ Jago, Professor of Paediatric Physical Activity & Public Health, reports some surprising findings from research conducted at the Centre for Exercise, Nutrition, and Health.

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Adolescent girls who attend after-school dance classes are no more likely to be physically active than those who don’t. This is one of the key findings from Active 7, a research project that aims to find out whether after-school dance sessions can help adolescent girls to engage in moderate levels of exercise.

Physical activity is associated with improved physical and mental health, but many adolescents – and particularly adolescent girls – do not engage in recommended levels of physical activity.  A team, led by staff in the Centre for Exercise, Health and Nutrition at the School for Policy Studies aimed to address this issue by examining whether providing dance programmes at secondary schools led to increases in girls’ physical activity. The study took place in 18 secondary schools. In half of the schools, Year 7 girls were provided with a new after-school dance programme for 20 weeks. Girls in the other “control” schools carried on as normal.

The results were surprising.  Much academic research suggests dance is an appealing form of physical activity amongst teenage girls, that extra-curricular periods are better suited to delivering physical activity interventions, and that interventions based on psychological theory (as Active7 was) have more success than non-theory based interventions. However, we found no difference between the physical activity levels of the intervention and control group girls at the end of the programme, or 6-months later. We also found that only a third of girls attended at least two thirds of the sessions provided in their school.

Our earlier work had suggested that girls enjoy dance and as such the lack of a difference in the physical activity levels of the girls was surprising. This could be due to the intensity of the dance sessions. The goal of the project was to increase ‘moderate to vigorous physical activity’ (MVPA), which gets you sweaty and slightly out of breath. The results found that girls who attended Active7 only took part in 4.7 more minutes of MVPA on session days, and therefore the sessions may not have been intensive enough to impact on MVPA.  Only one-third of the girls met the attendance criteria of attending two-thirds of the sessions, suggesting there may be a need to consider alternative forms of physical activity. A final and third explanation is methodological; accelerometers may not be able to capture the nuanced movements inherent in dance, especially when preparing for performances. Thus, levels of MVPA in sessions may have been underrepresented.

The results have implications for how we think about delivering after-school physical activity interventions. We might need to move beyond delivering standardised forms of extra-curricular physical activity and instead find more novel forms of exercise that offer lots of different types of physical activity. Fortunately, the findings from Active7 provide us with new ways of thinking about designing interventions. Offering participants with sufficient ‘choice’ in the design of the intervention is one potential method uncovered in our analysis, whilst delivering tailored interventions that meet a diversity of schools was also suggested as a future recommendation from girls and school contacts. Thus, future research which examines how to engage girls in activity and focusses on the types of activities that they would like to attend, when they would like to attend and how to maximise physical activity during those sessions, is needed.

The project was funded by the National Institute for Health Research Public Health Research (NIHR PHR) Programme (project number 11/3050/01). The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the NIHR PHR Programme or the Department of Health.

This blog post is based on Jago et al 2015: Effect and cost of an after-school dance programme on the physical activity of Year 7 girls: The Bristol Girls Dance Project, a school-based cluster randomised controlled trial, International Journal of Behavioral Nutrition & Physical Activity, 12:128, 2015

 

Capturing the benefits of ‘playing out’

School for Policy Studies academics work with a range of local interests. Playing out is a non-for-profit Bristol based organisation that encourages street play in the UK. Naomi Fuller, from playing out, has written this blog about how their work with the School is helping them to capture the benefits of such activity. 

I stood turning the skipping rope for ages at our last playing out session. Tall ten-year-olds and sturdy toddlers queued to have a go at jumping in as I chanted “Mickey Mouse Built a House” on request. I watched them – some skipping deftly, others stopping and starting with the rope getting tangled, some squatting down to do some chalking close by while they waited and I wondered whether it was possible to unpick what was going on. Of course they were having fun, giggling and trying to hold hands and skip together, then running out of the turning rope to add chalked horns to the rainbow-coloured cow they had drawn together in the middle of the street. But is there any way to measure this activity. And is there any need?PORTRAIT-grandma-skipping-rope.jpg

A conference hosted recently by University of Bristol gave some clear answers to these questions. The event was called “Outdoors and Active: Delivering public health outcomes by increasing children’s active travel and outdoor play”. It gathered people working in local authority public health teams, education and play services to share new research showing beyond doubt that children at playing out sessions are getting more exercise and activity than they would if they were indoors during that same period. Dr Angie Page and Professor Ashley Cooper are lead researchers for the PEACH project, a long term study examining the links between the different physical environments children spend time in and how active they are in them. They and their team have already measured children’s activity levels on their school journeys – whether in cars, on foot or by bike, during the school day and in the after-school period, examining the length of time they spend outdoors and indoors and exactly how much physical exercise they do.

To carry out these studies and gather the data they need, researchers have kitted children out with GPS tracking devices which show precisely their location at every stage of their journey. Children have also worn ‘accelerometers’ which measure the intensity of their exercise and activity. Recently Angie and her research team have turned their attention to street play – visiting playing out sessions to measure the intensity and type of physical activity children are doing. As well as equipping the children with the technical kit, her team interviewed parents and children about their activity patterns and habits.

It’s the levels of ‘moderate to vigorous physical activity’ (MVPA) that are a key focus. Government guidelines are clear: children between five and eighteen need to get at least an hour’s MPVA each day to ensure they are healthy. But very few are managing this and recent figures show just 14% of boys and 8% of girls are doing so. And these levels of inactivity are increasingly worrying for children’s long-term health and wellbeing. During a playing out session MVPA is the energetic play we often see; the skipping, scooting, hopscotch and playing tag as you would expect. But it’s brisk walking and similar types of activity as well and lots of imaginative games would include periods of MVPA as I’ve observed on my own street when make believe wizards and witches take to their broomsticks after huddling over a pretend cauldron for a while. The University of Bristol data shows;

  •  Children are three to five times more active outdoors than indoors
  • Time spent outdoors with friends is linked to an increase in children’s physical activity levels
  • During playing out sessions children spent 30% of their time in moderate to vigorous physical activity (MVPA) and another 15% in light activity.
  • This compares to 5% of time indoors usually spent in MVPA

Holding-one-end-skipping-ropeAngie Page introduced some important questions in presenting these findings. First was the notion of ‘subsitutional replacement’. Put in lay terms the issue is whether the children at the playing out session would have got their physical activity in another place such as their garden or local park if they hadn’t been playing in the street that day. The clear answer was no. The responses from parents and children showed that the playing out session was usually an alternative to a less active option – watching TV or another sedentary indoor activity.

And the other intriguing question was around the idea of ‘compensation’. This is the question of whether being active during a playing out session means children flop on the sofa for longer afterwards and are ironically less active than they would have been normally (as many adults often are after a gym session!). Again the data showed that this did not happen to the children playing out and that they did not have a pattern of doing less activity after playing out to ‘compensate’ for the more vigorous play they had done.

Professor Kevin Fenton, Director of Health and Wellbeing at Public Health England closed the conference by starkly stressing the urgency of improving children’s levels of physical activity and the need to make active play the norm once more. “It’s often said that the environment is an important health service,” said Professor Fenton. And he talked about both green spaces and urban spaces like streets, needing to be seen in this way – as potentially health-giving spaces for those spending time in them. The challenge both for the audience gathered at the conference, and for policy-makers and public health commissioners, is to support the idea of street environments as a ‘health service’ and to act on the growing body of research and data which clearly shows the benefits of street play. The evidence is there – not that anyone who has watched a playing out session has ever doubted it.

A few days after the conference my street played out again and this time as I watched the pink-cheeked skippers, legs blurred as they jumped faster and faster it felt inspiring to realise that what they were doing – so naturally and with so much fun – is part of something increasingly important to researchers and policy makers. You can read more about the University of Bristol’s research findings here. If you want to know how to support street play in your street, or work for an organisation interested in finding out more do get in touch.

This piece was originally posted on the playing out blog.