Healthy Weight: Diet vs. Exercise

The ABC’s Four Corners program exposed a fallacious corner of pharmacy this week, in its first program of 2017. By fallacious, I mean quackery. There are substances being suggested to susceptible patients, or more aptly, it seems from a pharmacist’s view: customers. It seems incredible that sane and rational pharmacology graduates could find themselves at counters, straight-faced, suggesting homeopathic remedies to partner serious maladies.

This is the sort of whiplash reality check that causes pause for thought. What do I believe and why? I used to believe that digital music was by far the best way to enjoy my favourite tunes. Turns out that spinning Roxy Music’s Avalon on vinyl is far superior to the MP3 version. All it took was a new turntable and a pre-amp, and I was converted. Who knew that I would be happily listening to 1982 tunes on vinyl in the 21st century?

So, if vinyl is superior to digital, what else do I need to change about my belief systems? AFL Women’s League is clearly the next big thing, so what else do I have wrong? I have had the pleasure to spend a serious amount of my clinical time not just treating triathletes, but many foot and ankle (F&A) injuries in the regular population. It’s initiated a re-synthesisation of injury modelling of my non-plastic science brain. It turns out that not all injuries are caused by athletic overuse!

Most of the F&A candidates I have seen are simply overweight. It’s a man (or lady) vs. gravity problem. And when I write ‘vs.’ kids, I mean versus not versing! So, their joints are wearing out from an overload, rather than sporting overuse. The problem is that these people are too heavy – gravity is winning the battle. Ground reaction force is the real issue – walking is one to two times gravity (so a 70kg person may experience 140kg through a series of joints in response to footfall). This increases to three to four times gravity  (up to 280kg) with jogging and six to eight times (~560kg) with all out running. So, I am not suggesting running!

As a doctor and physio, my job is to treat the injury, as well as the wider cause of the injury. The injury stuff is easy (in comparison). If it’s an Achilles, there’s a mix of rest, ice, stretching, massage, strength and proprioception training prior to returning to activity. But I need to address the weight problem to prevent recurrence. And the real challenge is causing a lasting, rather than transitory, change to a patient’s weight.

Before we continue, it’s worth taking a little look in the mirror. Sure, I have some chunky F&A patients, but they’re not trying to swim, ride and run for hours on end. I see many injuries in my triathlete patients who are simply ignoring their unsuitability for their chosen disciplines (distances). Somatotype (body shape) is a critical predictor of how robust or injury-resistant an athlete will be. That inherent shape should guide your choices for short versus long distance triathlon. If your weight is above a healthy BMI (weight:height, squared), athletes should consider sticking to shorter races in order to prolong their sporting longevity.

So, how to attack this problem? Obviously, lose weight. For each kilogram lost, top speed running ground reaction is reduced by six to eight kilograms. I found myself confronted by bewildered faces, as I talked about the amount of exercise required to return to a healthy weight. Linking weight loss and exercise is an intuitive way to attack the energy balance problem. Clearly, the equation needs to seesaw back to hunger: more energy expended than ingested through food. So, increasing energy output through exercise should lead to weight loss?

As it turns out, it’s more complicated than that. Weight loss, in particular loss of fat mass, is most successful when combining a dietary and exercise intervention (Stiegler and Cunliffe 2006). But I think this makes life a little too complicated for injured humans. Adding the rigours of exercise to someone with an arthritic ankle makes hard work of increasing energy expenditure. It dawned on me that simply being hungry is the vinyl of weight loss. If we look back 50-80 years ago, everyone was trimmer – largely due to lack of access to as many calories as we do now. And less sedentary jobs.

Can we change our jobs, to increase the amount of energy we expend? Probably not. So, best to stick to the low hanging fruit, which seems to be, simply, getting used to being hungry! De-coupling exercise and dietary intervention isn’t something I found intuitive until I was faced with all these injured patients whose activity capacity was inhibited by pain. The additional problem is that ingesting calories is enjoyable – in stark contrast to being hungry! And when no post-exercise endorphins are available, that and drinking, are the obvious options.

So, how to get used to being hungry? It’s not a forever option, but the 5:2 diet is a good choice (five days ‘normal’ eating and two days of restricted calories). This has the two-fold benefit of 1) educating athletes/patients about the energy content of food on their days of low intake, and 2) reminding people that a simple case of hunger will not kill them! Us modern humans are so used to reacting with distress to hunger and quickly ingest calories to treat the problem. The 5:2 diet provides evidence that hunger can be a positive feeling – in the context of weight loss, it means the diet is working. This reinforcement becomes a positive each day, rather than a negative.

I am not suggesting that athletes go off and start 5:2 dieting to improve their triathlon – rather that taking a look at your choices with a coach or a loved one may prolong your sporting life, and prevent you ending up getting a diet lecture on my treatment couch!

Train Well, Mitch.

Reference:  The role of diet and exercise for the maintenance of fat-free mass and resting metabolic rate during weight loss. Stiegler P1, Cunliffe A. Sports Med. 2006;36(3):239-62.

Feature image: Knezevic


Mitch Anderson

Dr. Mitch Anderson is one of the premier sports doctors in Melbourne working out his practice Shinbone Medical in North Melbourne. The former professional triathlete is your go-to triathlon doctor.

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