Abandon exercise? Only if you believe unevidenced opinion

April 23, 2015

Kamal Mahtani

Kamal Mahtani Deputy Director CEBM

This morning the BBC (and other media outlets) ran a headline dissociating any link between rising obesity levels and a lack of physical activity. The story originated from an editorial piece written in the British Journal of Sports Medicine British Journal of Sports Medicine and an associated press release. The article itself is largely about emphasizing the relation between excess calorie intake and obesity, but the dismissal of the importance of physical activity was dangerous, based on the headline news it generated.

The editorial article in the BJSM by Dr Aseem Malhotra (cardiologist) starts by citing the February 2015 report  from the UK’s Academy of Medical Royal Colleges titled: “Exercise: The miracle cure and the role of the doctor in promoting it”. Page 12 of the report says: ““Physical activity helps to manage over 20 chronic conditions, including coronary heart disease, stroke, type 2 diabetes, cancer, obesity, mental health problems and musculoskeletal conditions”.

So physical activity is good for us,.right? Right!

And Dr Malhotra was one of the co-authors of the Academy of Medical Royal Colleges report.

Well, read Dr Malhotra’s editorial article in the BJSM, and things get a little confusing. Here is what he writes:

“In the past 30 years, as obesity has rocketed, there has been little change in physical activity levels in the Western population.2 This places the blame for our expanding waist lines directly on the type and amount of calories consumed.”

Hold on. Let me just get that straight. So what you are saying is:

In the last 30 years:

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Is that it? Is that the basis for the claim?

The BBC article cite Dr Malhotra as saying: “An obese person does not need to do one iota of exercise to lose weight, they just need to eat less.”

Oh dear, this is getting worse! So why is Dr Malhotra touting the value of exercise as co-author of the Academy of Medical Royal Colleges report  “Exercise – The Miracle Cure?” and then advocating that obese individuals don’t need to be doing any physical activity?

And what was the evidence for

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that Dr Malhotra cited? Is it a systematic review? A realist review? Possibly even a specific trial? A complex intervention? In other words, proper evidence. …..None of the above, I’m afraid….. It’s from another opinion piece

It feels like it’s time to go back to the basics of evidence based medicine (big sigh).

Therefore here is open letter to Nick Triggle, BBC Health correspondent:

Dear Nick

You recently wrote an article for the BBC, titled “Exercise ‘not key to obesity fight’”. You cited an editorial written in the British Journal of Sports Medicine led by the cardiologist Dr Aseem Malhotra.

As a teacher and clinical practitioner I would like to explain the principles of evidence based medicine (EBM) to you. They revolve around patients (and the values dear to them), clinicians (and their knowledge and expertise from their clinical and social experience), and the best available medical evidence. When the combination of all 3 is applied to clinical decision making, only then can we say that one is practising evidence-based medicine. Granted, there will be times when one or more of the 3 principles takes greater precedence, but that is the beauty of EBM and the ability that it gives to tailor decisions to the needs of individual patients.

Nick, when evidence is used in decision making in this way, it should be good evidence, given that we are making decisions about people’s lives. Therefore, there is a hierarchy  of what counts as good sources of evidence. Unfortunately, expert opinion, the basis for your BBC report, is the lowest quality of evidence, as it comes with a high risk of bias.

Nick, as a health reporter, you and your colleagues in journalism have a responsibility to understand something about how evidence in medicine is acquired and applied and the implications of evidence for health care., I therefore invite you to come to spend a day with us to learn about EBM, in the hope that it will enrich your reporting.

Kind regards

Dr Kamal R. Mahtani BSc PhD MBBS PGDip MRCGP
GP & Deputy Director, Centre for Evidence Based Medicine

10 comments on “Abandon exercise? Only if you believe unevidenced opinion

  1. Very good comments. As I have mentioned to Dr Malhotra on twitter, studies have consistently shown that caloric restriction combined with either aerobic or strength (or, of course … and in my opinion the best option .. both!) training results in greater weight loss and increases glucose tolerance and insulin sensitivity in a variety of populations.

    I’m also still to find these public health messages which Dr Mulhatra referred to in which the public are encouraged to gorge junk food as long as they go to the gym.

  2. Exercise has many health benefits, but is indeed not needed for weight loss. In fact, severely obese individuals better wait until they lose the majority of the excess weight and start more vigorous exercise only at that point.

  3. Hello Kamal
    Continuing on from our discussion on Twitter, what is the evidence that increasing exercise is an important part of losing weight? It would be helpful if you could cite some of it in this piece.
    Many thanks

  4. AvatarJeremy Laurance

    Just as important Kamal is that you spend a day in Broadcasting House and learn how realistic it is for reporters writing three or four stories a day to do the job the researchers on the papers they are writing about are supposed to do. As throughout history, it’s the messenger wot gets the blame…

    • Dear Jeremy
      More than happy to. Closer working between scientists/medics/health researchers/editors can surely lead to better messages to patients and public? – I’m happy to stand corrected.

      I’ll email you to about spending a day at the Independent.

  5. Kamal,

    Thank you for writing this excellent letter broadcasting what the majority of informed health professionals were thinking about that BMJ editorial!

  6. Pingback: Did we really need to give people an excuse not to exercise? | Kamal R. Mahtani's blog

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