The fields of sport science and performance nutrition get considerable attention from the general public and mainstream media in comparison with other academic research circles, and popular topics that dominate headlines frequently divide opinion amongst experts. Moreover, common misconceptions are often presented by those in media circles in their interpretation of scientific findings, either inadvertently or in an effort to maximise public interest. As a result, it is imperative for scientists to discuss these polarising topics presenting unbiased evidence weighing one side of the debate versus the other using a structured approach.
Take for example a recent article in Reader’s Digest, which declares in its overarching point that “you can’t outrun a bad diet”, and that if you have to choose between one or the other, diet trumps exercise in terms of beneficially affecting weight loss. The problem with this is that the adage was popularised in recent years to emphasise the importance of a healthy diet to complement – and not replace – regular exercise.
All things considered, this saying is generally true as it’s easier to avoid eating a 1000+ calorie fast food meal in 30 minutes or less, while it would take multiple hours of intense exercise to burn this off in the gym or on the training pitch. However, I think that while well-intentioned these sort of sweeping statements send the message and is interpreted by the public that exercise is essentially irrelevant when it comes to weight loss and health. Another issue with this line of thinking is that diet plays a greater role in weight management than exercise when people have a terrible diet to begin with; and obviously when this is the case it’s an important lifestyle factor you should modify!
So if we look at the scientific evidence, what do we actually find when it comes to the effects of diet and exercise on weight loss? While diet and exercise regimens can both beneficially impact weight loss in long-term intervention studies, it has categorically been shown that combined lifestyle interventions (i.e. diet and exercise) have the most potent effect on these parameters. This has been demonstrated through a number of systematic reviews in overweight and obese populations, as well as in type 2 diabetes sufferers. Moreover, other reviews have also shown us that the most influential lifestyle factor which prevents skeletal muscle insulin resistance – a key determinant in obesity and type 2 diabetes progression – is unequivocally regular exercise.
Personally I think it’s time to stop making the diet vs exercise debate an either/or proposition. It’s clear from the literature, and from evidence-based practice that regular exercise and good nutrition go hand in hand when it comes to staying healthy and optimising weight loss. Both work, and when used in conjunction they provide a potent stimulus.
Coming back to the original reason for this post, the future of the relationship between scientists and the mainstream media remains unclear, but with the advent of social media in recent years it has become easier than ever to disseminate information quickly and efficiently. Conversely, it has also become equally easy to spread misinformation using these resources. It is up to members of the scientific community to responsibly report their findings to the media and general public in a clear, transparent manner and not overstate or extrapolate from their findings. Will this happen, and what are the potential consequences if it does? Regardless, it remains an area of intrigue and priority for scientists moving forward.
Tom Aird is a postgraduate student in the PESS Department. Tom.Aird@ul.ie View Toms Profile Here
For More Information:
- Diet or Exercise: The Final Verdict on Which Is Better for Weight Loss weblink
- Terranova, C.O., Brakenridge, C.L., Lawler, S.P., Eakin, E.G. and Reeves, M.M., 2015. Effectiveness of lifestyle‐based weight loss interventions for adults with type 2 diabetes: a systematic review and meta‐analysis. Diabetes, Obesity and Metabolism, 17(4), pp.371-378. weblink
- Franz, M.J., Boucher, J.L., Rutten-Ramos, S. and VanWormer, J.J., 2015. Lifestyle weight-loss intervention outcomes in overweight and obese adults with type 2 diabetes: a systematic review and meta-analysis of randomized clinical trials. Journal of the Academy of Nutrition and Dietetics, 115(9), pp.1447-1463. weblink
- Johns, D.J., Hartmann-Boyce, J., Jebb, S.A., Aveyard, P. and Group, B.W.M.R., 2014. Diet or exercise interventions vs combined behavioral weight management programs: a systematic review and meta-analysis of direct comparisons. Journal of the Academy of Nutrition and Dietetics, 114(10), pp.1557-1568. weblink
- Wu, T., Gao, X., Chen, M. and Van Dam, R.M., 2009. Long‐term effectiveness of diet‐plus‐exercise interventions vs. diet‐only interventions for weight loss: a meta‐analysis. Obesity reviews, 10(3), pp.313-323. weblink
- Nelson, R.K., Horowitz, J.F., Holleman, R.G., Swartz, A.M., Strath, S.J., Kriska, A.M. and Richardson, C.R., 2013. Daily physical activity predicts degree of insulin resistance: a cross-sectional observational study using the 2003–2004 National Health and Nutrition Examination Survey. International Journal of Behavioral Nutrition and Physical Activity, 10(1), p.10.weblink
- Way, K.L., Hackett, D.A., Baker, M.K. and Johnson, N.A., 2016. The effect of regular exercise on insulin sensitivity in type 2 diabetes mellitus: a systematic review and meta-analysis. Diabetes & Metabolism Journal, 40(4), pp.253-271. weblink
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