The eternal weight loss question: diet or exercise


Sam Bailey

Hands up if your January #fitgoals didn’t quite happen and the belly bulge is still rudely hanging around?

Well, you’re not alone. A new Dieticians Association of Australia survey revealed more than half of Australians want to lose weight.

And a new Nielsen research report shows 78 per cent of Aussies are taking initiative by prioritising their diet first (over exercise), as a way to combat fat.

What does this mean? The age-old exercise versus diet debate is a timely topic.

But how are we really meant to know what is best and who to believe (and what will get rid of that blasted belly)? We’ve enlisted the help of two health experts to run us through the pros and cons of this weighty debate.

The diet expert

Professor Vicki Flood, Professor of allied health, accredited practising dietician and nutrition and dietetics expert from the University of Sydney’s Faculty of Health Sciences runs us through her thoughts

  1. What evidence is there to suggest diet is key to weight loss?

A systematic review in 2014, dating back to the 80’s analysed over 3,500 participants and compared those who did a combination of diet and exercise, versus diet only and versus exercise only (specifically looking at those classified overweight or obese) and found after twelve months, the best outcomes are in fact a combination of diet and exercise – both showed optimal health outcomes in terms of reduced blood pressure and fat mass.

However, when they looked at the separate diet versus exercise groups (not the combination group) there was more sustained weight loss in the diet only group. So, overall the body of evidence showed diet only had more benefit than exercise only for weight loss.

  1. What about doing exercise only though?

Sticking to exercise only is a hard call as we tend to eat too much, so you have to work really hard during a workout whereas when you reduce calorie intake, the classic thing your body does to compensate is slow the metabolism down – which is why exercise is important. Exercise helps maintain muscle mass but reduce fat mass (and muscle mass helps drive metabolism) so a combination is important.

  1. If you do exercise regularly can this balances out a bad diet?

Theoretically, if you did lots of activity you can create a degree of balance. I wouldn’t say it would never work for anyone – especially for those who might be following a good diet already. But it’s so important that people think of their diet as a healthy way of eating over a whole lifetime.

It’s not to say an occasional piece of birthday cake is not allowed, but we have a society now that’s surrounded by junk food all the time, so we really can’t get into the habit of having junk food on a daily basis, it should be occasional.

  1. So what constitutes a good, healthy diet for weight loss?

Firstly, people need to be thinking about healthy eating as a lifestyle choice over a long period of time.

In terms of food, I recommend a predominately plant based diet – fruit, vegetables and legumes are all high fibre and help fill us up. Proteins also help us feel full as well. So a combination of these foods, very much a Mediterranean type diet.

It’s important to note though, different things work for different people – some people thrive off a high protein/low GI diet, but for some people find the protein recommendation too high to sustain. There can be success in paleo as it cuts out junk food, but then the concern is they cut out other core things like dairy and legumes.

  1. Should a diet approach be different for those overweight versus those wanting to shift a couple of kilos?

For someone who is overweight, they might need to lose weight for other health reasons such as diabetes; in which case, they might need to go on a strict diet such as a low calorie diet.

But they do importantly need to learn healthy habits too in order to sustain weight loss and muscle mass in the future.

Whereas, for someone with a couple of kilos, it’s about making small lifestyle changes. This can be really difficult, as it often means looking at fundamental things you can get rid of in your diet. Often portion sizes can be the problem or alcohol. Alcohol is energy dense as fat, so we need to get out of a regular habit.

In the Mediterranean diet, one glass with a meal is okay – but that’s it. While red wine might contain polyphenols but you can also get them from olive oil, tea, green vegies, berries, blueberries and cherries.

The exercise expert

We spoke to Dr Helen O’Connor, senior lecturer in the Discipline of Exercise and Sport Science in the faculty of Health Sciences at the University of Sydney.

  1. What’s your take on exercise over diet for weight loss?

Exercise is incredibly important for so many reasons – metabolic health, muscle mass, psychological health and also weight loss.

A trap people tend to get into thinking though is that if they exercise, they can lose weight overnight. The number of kilojoules you expend for an hour of exercise, might not balance out with that piece of chocolate cake – which can take a couple of hours to burn off so people aren’t always aware of the energy balance equations i.e. how much energy/kilojoules you get out of each meal. And the reality is we often don’t do enough physical activity to then warrant that.

If you’re trying to lose weight only with exercise, I do believe in the long run, you need to balance your exercise and the energy you eat from food – it’s like picking up something with one hand, not two, why would you?

  1. What exercise should we be doing to shed more weight?

Okay – the bottom line is, evidence from the American College of Sports Medicine shows moderate intense activity 150-250 minutes a week is the most effective way to prevent weight gain.

This is specifically focusing on aerobic activity, aka cardio. The AMCS stand is that cardio is most effective form of exercise for losing weight, however, resistance training is important for sustaining lean mass. Think of lean mass like an engine, it burns the fuel – so you don’t want to lose lean mass, you want to target fat loss – which is where resistance training is good.

Overall though, they don’t support resistance training for weight loss, with or without diet restriction.

  1. What are the biggest barriers do you think for people not reaching fitness goals needed to lose weight?

There’s often a misconception that if you’ve done a workout three times a week then that’s enough, but when you should be doing at least 150-250 minutes a week to lose weight, often a couple of sessions won’t cut it. People are better to build that activity into their day more – for example, going for a fast walk at lunchtime.

We also need to be mindful of exercise as a weight loss tool. Think of it like a credit card balance – you need to balance spending with income, if you don’t balance everything ends up in the red.

For some people new to fitness, it can be as tough. Instead of making unrealistic goals, look for opportunities to be active day-to-day – individualise workouts to suit you – whether it’s cycling, swimming or walking. It’s no one size fits all recipe.

Lastly, while it might be easier for those in higher socio economic backgrounds to pay for a trainer and expensive shoes, if you can walk you don’t need to see a trainer or a gym, sometimes exercising just with others can be motivation in itself.

The government offers information on their Healthy Active website and most councils (such as the NSW Get Healthy) provide free health coaching hotlines or walking groups.

The bottom line

There’s no one magic answer or quick fix to the age-old issue. Both experts conclude it’s about doing a mix of both. But if you need a cheat sheet to sum it up, here are the key takeaways:

  • Balance the energy you consume with the energy you expend.
  • Stock up on leafy green veggies, extra virgin olive oil and legumes.
  • Cut back on alcohol.
  • Aim for 150-250 minutes of exercise each week.
  •  Focus on cardio with resistance training.
  • Work out with friends.
  • Don’t get caught up with a one-size-fits-all approach – individualise diet and exercise to suit you and your lifestyle.




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