In the minds of many a weight loss aspirant, the quest to find the silver bullet often pits diet and exercise against each another in a showdown with all the intensity of a boxing showpiece. “In the left corner, backed by a multi-million dollar weight loss industry and weighing in less-than-it-did-last-week: DIET! (Cheer) And in the right corner, wearing the not-so-flattering bike shorts and carrying the hopes of personal trainers everywhere: EX-“no pain, no gain”-ERCISE. (Cheer). And now ladies and gentleman, we are about to see the end of decades of speculation and crown the victor of this bout with the one-size-fits-all title of weight loss king of the world! So let the battle begin!” (And the crowd goes wild).
Now, in my profession, I come across those steadfastly camped in either corner of the ring ready to defend their champion and point out the flaws of the opposing force. “Diets don’t work” some will say, while in response others will look to point out the unsustainable demands of rigorous exercise both on our knee caps and our time. So what’s the answer – who wins the fight – who is the champion between these two formidable opponents?
Well, perhaps not surprisingly, I am one of those with both feet planted firmly in the diet camp, rubbing the shoulders and singing the praises of the champ to be (metaphorically speaking). But my support of food (or less of it) as the superior weight loss process is not just a biased opinion, but rather a position steeped in scientific studies and research.
Now, don’t get me wrong, one of my favourite quotes is from WM Bortz of the American College of Sports Medicine who said, ‘There is no drug in current or prospective use that holds as much promise for sustained health as a lifetime of physical exercise” – well said Mr Bortz! However, when it comes to weight loss, exercise not only can’t hold its own against diet, but is actually fairly useless. What? Useless? Yes that’s what I said and yes I realise that this is going against the most commonly held assumption going around today (i.e. If you exercise you will lose weight). So let me explain.
A few years ago, Dr Wayne Miller and his colleagues reviewed 493 weight loss studies to determine whether adding exercise to a restricted calorie diet would accelerate weight loss. 25 years of research showed that exercise provided only a marginal weight loss benefit when compared to diet. That is, from all the studies reviewed, dietary restriction alone resulted in an average weight loss of 7.8kg over a 15 week period. Adding exercise to dietary restriction merely added another 1.2kg giving a total of 9.0kg loss (while 1.2kg is nothing to sneeze at, I know who’s side I’d rather be on in a fight).
Further to this, in their published research, Dr Timothy Church’s team described a principle of compensation. That is, those who exercised more in his study, ate more or compensated in another way (like moving less when they got home from the gym) which resulted in a less-than-expected weight loss.
While I don’t expect the two above mentioned studies to end the discussion once and for all, they are just the tip of the iceberg when it comes to seeing inconsistent (at best) weight loss from exercise. I do however hope this helps to answer that frustrating question “How come I’m not losing weight?” Well, it’s probably got less to do with the gym workout you missed and more to do with the muffin you had with your coffee this afternoon.
Again, please don’t get me wrong – exercise has many amazing benefits for our health – so please keep incorporating it into your lifestyle. However, simply find something you enjoy and if you’d like to lose weight, speak to an accredited practicing dietitian.
 Miller WC, et al. (1997) A meta-analysis of the past 25 years of weight loss research using diet, exercise or diet plus exercise intervention, International Journal of Obesity, vol. 21, pp. 941 - 947
 Church TS, et al. (2009) Changes in Weight, Waist Circumference and Compensatory Responses with Different Doses of Exercise among Sedentary, Overweight Postmenopausal Women. PLoS ONE 4(2): e4515. doi:10.1371/journal.pone.0004515
Image from: www.goodhealthyadvice.com.au