On 2016 Oct 19, David Nunan commented:

We wrote an editorial on this open access editorial but ours was put behind a paywall. In addition, the open access editorial also received the following: - numerous promotional tweets from the @BJSM account (ours received one at the time of its release) - a podcast https://soundcloud.com/bmjpodcasts/you-cant-outrun-a-bad-diet-draseemmalhotra-on-weight-loss-strategies - Reference in a blog http://blogs.bmj.com/bjsm/2015/05/21/its-not-just-bjsm-talking-about-healthy-nutrition-real-food/

To attempt to redress the balance, here we provide an abriged pre-published version of our editorial piece for interested readers.

Malhotra and colleagues highlight the important health benefits of physical activity in cardiovascular disease, type 2 diabetes, dementia and cancer but dismiss any benefit for weight loss in obesity.1 However, the poor use of existing evidence to underpin this dismissal and the resultant press release generated headlines that send a misleading message to patients and the public.

Poor use of evidence.

An evidenced-based approach to clinical decision making involves understanding the best type of evidence to use, how to appraise it, and assessing its usefulness in practice. Such an approach determines the risk of bias and ensures decisions are guided by accurate, meaningful evidence. The GRADE guidelines cite expert opinion alone as very low quality evidence, with a high risk of bias.2 Unfortunately much of the evidence cited by Malhotra and colleagues was based on expert opinion or was not referenced. For example, when excluding a relationship between obesity and physical activity, the evidence cited was an opinion piece by Luke & Cooper3, which has been criticised for ignoring observational and experimental studies that support a relation between physical activity and obesity. They give no reference for their claim that according to the Lancet Global Burden of Disease report poor diet now generates more disease than physical inactivity, alcohol, and smoking combined.

Current recommendations for physical activity in obese patients.

To substantiate their dismissal Malhotra and colleagues would have to provide better evidence to justify why current guidance is wrong. The World Health Organisation currently recommends that obese and overweight individuals engage in regular physical activity (60 minutes a day for children and 150 minutes per week for adults).4 National Institute for Health and Care Excellence (UK) guidance advises health professionals should support obese patients in increasing their physical activity, particularly through activities that fit easily into their everyday life.5 Recognising the value of physical activity in promoting a healthy lifestyle, including in obese patients, the Academy of Medical Royal Colleges recently issued its report Exercise: the Miracle Cure, which summarised the evidence on physical activity and called on doctors “to promote the benefits of regular physical activity to their patients and to communities in their wider roles as ‘advocates for health’.”6 They also highlight systematic review evidence that body weight may stay the same despite a reduction in high risk visceral fat as a result of increased muscle mass.

Current evidence for physical activity and obesity.

The Malhotra editorial challenges the effectiveness of physical activity for weight loss in obese individuals. The guidelines and reports highlighted above present much of the evidence base and include a specific Cochrane systematic review by Shaw and colleagues7 which was ignored by the Malhotra editorial. This review included 43 studies reporting results from 41 randomised controlled trials including a total of 3476 participants. The duration of included studies ranged from 3 to 12 months (61% less than 4 months), including follow-up. Although methodological quality for included studies was variable according a risk of bias assessment, the Cochrane review authors report that exercise combined with diet resulted in greater weight reduction than diet alone (mean difference -1.0 kg; 95% confidence interval (CI), -1.3 to -0.7). They also note the finding that increasing exercise intensity increased the magnitude of weight loss (mean difference -1.5 kg; 95% CI -2.3 to -0.7). An additional finding was that exercise improved a range of secondary outcomes even when weight loss did not occur. The authors conclude exercise was an effective weight loss intervention, particularly when combined with dietary interventions but make no inference to the poor quality of included trials and little reference to the fact that diet alone appeared better than exercise alone (mean difference -3.6 kg, 95% CI -4.3 to -3). Whether these differences are meaningful requires good clinical judgement and open, honest discussion.

These outcome and quality findings are repeated in a more recent systematic review assessing treatment (including diet, exercise or diet and exercise) for overweight and obesity in adult populations.8 When objectively assessing the best available evidence, for which we acknowledge the majority is of low quality, it would appear that diet alone (mainly low fat) is better than exercise alone but diet and exercise both are better than either. A further key point is that improvements in important health risk factors are observed with exercise even without weight loss.

Conclusions

There is little doubt that diet is key in the management of the obesity epidemic. What is less helpful, and does no-one, including the public and patients, any favours, is the production of opinion pieces that use evidence poorly or not at all.

References 1. Malhotra A, Noakes T, Phinney S. Editorial: It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br J Sports Med doi:10.1136/bjsports-2015-094911 2. Howard Balshem Mark Helfand, Holger J. Schünemann, Andrew D. Oxman, Regina Kunz, Jan Brozek, Gunn E. Vist, Yngve Falck-Ytter, Joerg Meerpohl, Susan Norris, Gordon H. Guyatt. GRADE guidelines: 3. Rating the quality of evidence July 30, 2010; Published Online: January 06, 2011 3. Luke A, Cooper RS. Physical activity does not influence obesity risk: time to clarify the public health message. Int J Epidemiol 2013; 42(6): 1831-6. 4. http://www.who.int/mediacentre/factsheets/fs311/en/. Accessed 28 April, 2015 5. http://www.nice.org.uk/guidance/cg43/resources/guidance-obesity-pdf. Accessed 28 April, 2015 6. http://www.aomrc.org.uk/general-news/exercise-the-miracle-cure.html. Accessed 28 April, 2015. 7. Shaw KA, Gennat HC, O’Rourke P, Del Mar C. Exercise for overweight or obesity. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD003817. DOI: 10.1002/14651858.CD003817.pub3. 8. Peirson L, Douketis J, Ciliska S, Fitzpatrick-Lewis D, Usman Ali M, Raina P. Treatment for overweight and obesity in adult populations: a systematic review and meta-analysis CMAJ Open. 2014 Oct-Dec; 2(4): E306–E317. Published online 2014 October 1. doi: 10.9778/cmajo.20140012.

On 2016 Oct 19, David Nunan commented:

We wrote an editorial on this open access editorial but ours was put behind a paywall. In addition, the open access editorial also received the following: - numerous promotional tweets from the @BJSM account (ours received one at the time of its release) - a podcast https://soundcloud.com/bmjpodcasts/you-cant-outrun-a-bad-diet-draseemmalhotra-on-weight-loss-strategies - Reference in a blog http://blogs.bmj.com/bjsm/2015/05/21/its-not-just-bjsm-talking-about-healthy-nutrition-real-food/

To attempt to redress the balance, here we provide an abriged pre-published version of our editorial piece for interested readers.

Malhotra and colleagues highlight the important health benefits of physical activity in cardiovascular disease, type 2 diabetes, dementia and cancer but dismiss any benefit for weight loss in obesity.1 However, the poor use of existing evidence to underpin this dismissal and the resultant press release generated headlines that send a misleading message to patients and the public.

Poor use of evidence.

An evidenced-based approach to clinical decision making involves understanding the best type of evidence to use, how to appraise it, and assessing its usefulness in practice. Such an approach determines the risk of bias and ensures decisions are guided by accurate, meaningful evidence. The GRADE guidelines cite expert opinion alone as very low quality evidence, with a high risk of bias.2 Unfortunately much of the evidence cited by Malhotra and colleagues was based on expert opinion or was not referenced. For example, when excluding a relationship between obesity and physical activity, the evidence cited was an opinion piece by Luke & Cooper3, which has been criticised for ignoring observational and experimental studies that support a relation between physical activity and obesity. They give no reference for their claim that according to the Lancet Global Burden of Disease report poor diet now generates more disease than physical inactivity, alcohol, and smoking combined.

Current recommendations for physical activity in obese patients.

To substantiate their dismissal Malhotra and colleagues would have to provide better evidence to justify why current guidance is wrong. The World Health Organisation currently recommends that obese and overweight individuals engage in regular physical activity (60 minutes a day for children and 150 minutes per week for adults).4 National Institute for Health and Care Excellence (UK) guidance advises health professionals should support obese patients in increasing their physical activity, particularly through activities that fit easily into their everyday life.5 Recognising the value of physical activity in promoting a healthy lifestyle, including in obese patients, the Academy of Medical Royal Colleges recently issued its report Exercise: the Miracle Cure, which summarised the evidence on physical activity and called on doctors “to promote the benefits of regular physical activity to their patients and to communities in their wider roles as ‘advocates for health’.”6 They also highlight systematic review evidence that body weight may stay the same despite a reduction in high risk visceral fat as a result of increased muscle mass.

Current evidence for physical activity and obesity.

The Malhotra editorial challenges the effectiveness of physical activity for weight loss in obese individuals. The guidelines and reports highlighted above present much of the evidence base and include a specific Cochrane systematic review by Shaw and colleagues7 which was ignored by the Malhotra editorial. This review included 43 studies reporting results from 41 randomised controlled trials including a total of 3476 participants. The duration of included studies ranged from 3 to 12 months (61% less than 4 months), including follow-up. Although methodological quality for included studies was variable according a risk of bias assessment, the Cochrane review authors report that exercise combined with diet resulted in greater weight reduction than diet alone (mean difference -1.0 kg; 95% confidence interval (CI), -1.3 to -0.7). They also note the finding that increasing exercise intensity increased the magnitude of weight loss (mean difference -1.5 kg; 95% CI -2.3 to -0.7). An additional finding was that exercise improved a range of secondary outcomes even when weight loss did not occur. The authors conclude exercise was an effective weight loss intervention, particularly when combined with dietary interventions but make no inference to the poor quality of included trials and little reference to the fact that diet alone appeared better than exercise alone (mean difference -3.6 kg, 95% CI -4.3 to -3). Whether these differences are meaningful requires good clinical judgement and open, honest discussion.

These outcome and quality findings are repeated in a more recent systematic review assessing treatment (including diet, exercise or diet and exercise) for overweight and obesity in adult populations.8 When objectively assessing the best available evidence, for which we acknowledge the majority is of low quality, it would appear that diet alone (mainly low fat) is better than exercise alone but diet and exercise both are better than either. A further key point is that improvements in important health risk factors are observed with exercise even without weight loss.

Conclusions

There is little doubt that diet is key in the management of the obesity epidemic. What is less helpful, and does no-one, including the public and patients, any favours, is the production of opinion pieces that use evidence poorly or not at all.

References 1. Malhotra A, Noakes T, Phinney S. Editorial: It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br J Sports Med doi:10.1136/bjsports-2015-094911 2. Howard Balshem Mark Helfand, Holger J. Schünemann, Andrew D. Oxman, Regina Kunz, Jan Brozek, Gunn E. Vist, Yngve Falck-Ytter, Joerg Meerpohl, Susan Norris, Gordon H. Guyatt. GRADE guidelines: 3. Rating the quality of evidence July 30, 2010; Published Online: January 06, 2011 3. Luke A, Cooper RS. Physical activity does not influence obesity risk: time to clarify the public health message. Int J Epidemiol 2013; 42(6): 1831-6. 4. http://www.who.int/mediacentre/factsheets/fs311/en/. Accessed 28 April, 2015 5. http://www.nice.org.uk/guidance/cg43/resources/guidance-obesity-pdf. Accessed 28 April, 2015 6. http://www.aomrc.org.uk/general-news/exercise-the-miracle-cure.html. Accessed 28 April, 2015. 7. Shaw KA, Gennat HC, O’Rourke P, Del Mar C. Exercise for overweight or obesity. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD003817. DOI: 10.1002/14651858.CD003817.pub3. 8. Peirson L, Douketis J, Ciliska S, Fitzpatrick-Lewis D, Usman Ali M, Raina P. Treatment for overweight and obesity in adult populations: a systematic review and meta-analysis CMAJ Open. 2014 Oct-Dec; 2(4): E306–E317. Published online 2014 October 1. doi: 10.9778/cmajo.20140012.