Obesity researchers have been in a tug-of-war for decades now — is obesity really that bad for us, or isn’t it? Is it getting worse or better? Is it a matter for individual choice or collective action? And in the past week, there’s been a new offensive in the obesity wars.
The authors of a rather incendiary editorial published in the British Journal of Sports Medicine started this round with the claim that the main cause of obesity was overeating, particularly eating too much refined carbohydrate. And, they added, physical activity plays little, if any role.
“You can’t outrun a bad diet,” they write, specifically attacking Coca-Cola for its line “all calories count”, which they say suggests “it is ok to consume their drinks as long as you exercise.”
What silence followed didn’t prevail for long. In a typically blistering response, Dr Steven Blair, writing on behalf of the Global Energy Balance Network which is partly funded by Coca-Cola, attacked the authors for flawed research and failure to disclose commercial interests.
The debate has put a spark to the tinder of a debate that’s been smoking for several years. Blair exchanged fire with other research luminaries in a 2013 skirmish when two US researchers claimed that public policy around obesity should have just one focus: controlling the food environment.
This debate is the obesity world’s equivalent of the Game of Thrones. It has everything: it pits armies of dietitians against physical activity researchers; it’s rich with aggressive accusations of pandering to base commercial interests; and it launches bombshells of academic delinquency if not outright fraud.
But first…
So where does the truth lie? Well, I shall reveal all. But first, let’s get one thing out of the way, because I can already hear the thunder of ad hominem attacks on the horizon.
I received direct funding, albeit quite modest, from Coca-Cola in 2014 to present at a conference in Dubai on physical activity. They also once sent me a very nice basket of fruit for a talk I gave to their executives.
![](https://62e528761d0685343e1c-f3d1b99a743ffa4142d9d7f1978d9686.ssl.cf2.rackcdn.com/files/79412/width668/image-20150427-23932-bsltdq.jpg)
And I’ve been involved in international projects led by groups that receive funding from the Coca-Cola company, but for which neither I nor my institution have received direct funding.
I have also received funding from the National Health and Medical Research Council, the Australian Research Council, Beyond Blue, the Department of Defence, the National Heart Foundation and Healthway, among many other government bodies and non-government organisations supporting research. And I receive royalty payments from UNSW Press, bless them.
The two sides
Fire from the opposed camps — diet versus exercise — has been focused on two key strategic points: whether physical activity promotes weight loss; and whether the obesity epidemic is almost entirely due to increases in energy intake rather than decreases in energy expenditure.
Let’s take these one at a time.
Does physical activity promote weight loss? The short answer is that it can, but you need to do an awful lot of physical activity. And it’s nowhere near as effective as diet. It appears to be easier to diet ourselves thin than to exercise ourselves thin.
The American College of Sports Medicine recommends a minimum of 250 minutes a week of exercise for long-term weight loss. And 150 to 250 minutes a week to prevent weight gain. But diet consistently outperforms exercise for weight loss, while diet plus exercise outperforms both.