Obesity Panacea

Energy Balance & Body Weight

One theme that popped up repeatedly at the conference was the issue of exercise/energy balance and body weight.  The conference began on Wednesday afternoon with a session on the topic chaired by Dr Steve Blair.  The first speaker was Dr John Blundell of Leeds University.  Dr Blundell discussed research from this recent study published in the International Journal of Obesity which demonstrates the huge variation in weight loss when individuals are exposed to an exercise program (see Figure 1 on page 27).  For example, in 30 subjects exposed to 12 weeks of aerobic exercise, the average weight loss was 3.7 kilograms.  However, some individuals lost as much as 14 kg, while 4 participants actually gained weight.  Dr Blundell used this evidence and other similar studies to suggest that the "average" weight loss in response to exercise is often meaningless, given such extreme variation.  However, his data also suggested that among those who lost little weight, and even among those who gained weight, there was still a consistent reduction in fat mass, waist circumference, and an improvement in other health indicators (the increased weight was largely due to increased muscle mass).   In another session on a similar topic, Dr Tim Church suggested that reductions in workplace physical activity levels accurately predict the increase in obesity over the past 60 years.  And at the closing banquet, Dr Levine discussed his own work which has shown that individuals vary widely in their ability to prevent weight-gain through increased physical activity when forced to consume 1000 extra calories per day.

I think that these issues of responders vs non-responders may also explain the differences of opinion that many people have on the role of exercise in weight management.  Looking at this study  by John Blundell or this one by Chris Riddoch, it's difficult to argue that exercise plays no role whatsoever in weight management.  However, I can see why our colleagues in primary care would disagree, since they would be most likely to encounter the "non-responders" that Dr Blundell referenced in his speech - why would a "responder" continue seeking treatment?  I'm not saying this explains everything, but I think it can help explain why the evidence on this topic is so mixed, making it very difficult to come to any definite conclusions (or allowing people to come to very different conclusions).

This is an issue that I want to come back to in the future, but suffice it to say that the issue of exercise and body weight is a complicated one.  Exercise can clearly reduce body weight in the short-term, as many studies by my MSc supervisor Bob Ross have shown time and again.  However, there also appear to be consistent findings that some people lose far more weight than others, and in general I think we can all agree that focusing solely on exercise is a poor plan if you're goal is long-term weight loss.  Similarly, exercise may not completely prevent weight gain when exposed to an excess of calories, although it can clearly help, as we've discussed in the past.  As Dr Blundell summed it up, the effect of exercise on body weight is not spectacular, but the findings are generally positive.  By the end of the conference I was personally starting to tire of this whole debate, and I agree wholeheartedly with Dr Blundell that we need to move away from such a narrow focus on body weight given the wealth of evidence showing the exercise is associated with numerous health benefits regardless of what is happening with body weight. 

Public-Private Partnerships

As many people know, this recent conference was sponsored by Coca-Cola.  This led to some excitement on the opening night of the conference, when George Davey Smith criticized the food and beverage industry, claiming that they have misrepresented the association between soft drink consumption and health.  I wasn't able to attend the opening plenary myself, but the PLoS Speaking of Medicine blog has written their account of Dr Smith's speech here.  This is obviously another tricky issue - a soft-drink company sponsoring a health conference - made more complicated by the fact that the conference would likely have been almost impossible without their financial support.  Is it better to have no conference at all, or a conference sponsored by a company that sells sugar-laden beverages?  Is it better to engage the industry, or avoid them completely?  These questions are all well above my pay scale, but I heard a lot of delegates discussing them throughout the conference, which seems like a good place to start.

The Toronto Charter on Physical Activity

I discussed the Charter in my post last week leading up the conference, and it wound up being a highlight for me personally, and many of the other delegates that I've spoken to.   The final draft of the Charter is now available here.  In short, the Charter is a tool which can be used to advocate for increased physical activity as a means of increasing the health and productivity of society.  The Charter has had input from more than 400 individuals from over 50 countries, and is likely to be a watershed document in the promotion of physical activity (it was also signed by more than 500 delegates, including myself!).  It includes concrete suggestions on ways to advocate for increased physical activity at all levels of society.  If you work in any field remotely related to physical activity (public health, sport and rec, education, city planning, you name it!) then this document can help you advocate for increased physical activity.  The authors of the Charter have urged everyone to share 5 copies of the Charter with their friends and/or co-workers, and to ask them to do the same.  I've just shared it with all of you, now go share it with the world! And to see what Speaking of Medicine is saying about the Charter, click here.

Final Thoughts

That pretty much sums up my experience from the past week!  I realize that I didn't even mention my poster, which went well but wasn't quite as exciting as some other parts of the conference (which is to be expected from a poster presentation).  I should mention that I was also able to meet quite a few readers of the blog, which is exciting - I'm still amazed that we have any readers aside from Peter and myself!.

I learned about a lot of cool stuff at this conference, and I'm hoping to expand on the issues that I've discussed above in future posts.  ICPAPH was a terrific experience, and I'd urge everyone to save up for the next Congress which will take place in Sydney, Australia in the fall of 2012 [let me know if anyone has a spare couch where a grad student/blogger could crash for a couple nights... :) ].  The powerpoint slides from all of the plenary sessions, as well as the final draft of the Charter should be available on the conference website in the near future, and I'll put up a new link as soon as that happens.

What were other peoples' experience of the conference?

Travis