So, you've gone to the gym, worked hard and burned off some calories. Now what? Do you eat those calories back, or do you add them to the “calorie bank” and save them up for a special occasion? Here's what our Dietitians have to say.

Calories In, Calories Out

Firstly, let's clarify that we are writing this article for someone looking for active weight loss, over someone looking to maintain or gain weight. So, for anyone looking to lose weight, with no other factors at play, we would say “no” - save those bad boys for a wine on Friday night!

At its most basic level, weight is the outcome of the amount of energy we consume minus the amount of energy we use. The deficit (or surplus) at the end of each day / week / year will determine whether we gain weight, lose weight or maintain our weight.

On top of this, we also know that individuals seeking weight loss will lose ~2kg more, on average, when they combine moderate levels of physical activity with a “healthy diet” than those who lose weight through dietary intervention alone.

This is partly because exercise helps to boost satiety hormones (the things that make us feel fuller, for longer) for up to 24 hours, which in turn results in smaller portions and more balanced decisions regarding food. It is also due to the beneficial effect exercise has on preserving lean tissue and bone density, and the resultant increase in our Basal Metabolic Rate (BMR) up to 24 hours post exercise.

Not surprisingly, if we are “burning more energy, for longer” and feel “fuller, for longer” it becomes easier to achieve a larger deficit for weight-loss than those who alter their diet alone.

Amount & Intensity

Now, of course nothing is ever that simple, and this holds true with regard to exercise and nutrition. You see, the answer to that delicious question “should I eat back my exercise calories?” also depends on the amount, and intensity, of said exercise.

Scientific studies have demonstrated that the fuel we burn at different exercise intensities changes. When we are in low-moderate heart rate zones, we primarily rely on fat as our ideal fuel.  However, when we increase our heart rate and enter into a high (or cardiovascular) zone, our body will swap to burning carbohydrates. Because of this, the effect this has on our need to “eat back” our calories is largely determined by the duration we are in these different heart rate zones, in addition to our baseline diet.

Let us consider the following scenarios:

• Suzie is a 40 year old female who has successful lost 10kg, but is seeking to lose 20kg overall. In her journey to lose 10kg, Suzie made a commitment to reach 10,000 steps per day as many days of the week as possible. In service of this goal, she started to walk into work, to take a walk in her lunch break a couple of times a week and, to take her dog out for a play in the park on the weekend. In losing 10kg, Suzie now feels more energetic. One of her work colleagues is a seasoned triathlete. He knows that Suzie is seeking a more active lifestyle and suggests she joins him in training for a triathlon! Her training program comprises of regular runs, cross training and some body weight exercises. All of her exercise is performed early in the morning, before breakfast. Unfortunately, since starting her training, Suzie has noticed that she is feeling tired, has sore muscles and finds herself wanting to “snack” a little more. She has also noticed that her weight-loss, whilst initially bolstered, has started to slow.
• Steve is in his early 50s and has lost 25kg. He is now at his ideal weight and has been maintaining his weight for the last six months. During this time he has been engaging in regular exercise, a mixture of gym work-outs and cycling. He has started some long-distance cycles on the weekends and noticed that his weight has gradually reduced, and with that some of his performance/strength.
• Sophie is 32, doesn’t have a history of being very physically active and is at the start of her weight-loss journey. She has modified her diet to be more in line with the Australian Guide to Healthy Eating, consuming more vegetables, fruits and dairy. She has also made some changes during her working day that have allowed her to eat regularly, forgoing those long 6-7 hour stints between meals! So far, she has lost 2kg and now feels that it is time to introduce some movement into the equation. She has been to see an Exercise Physiologist and has been given advice on walking and some light body weight exercises. Since introducing her exercise, Sophie has noticed that she is feeling more energetic and no longer feels as hungry in the afternoon – which has historically been a challenging time of the day for Sophie, to say no to the biscuits on offer in the tea room at work. When walking with a friend one morning, Sophie’s diet comes into the spotlight, and she is given the advice that she should “eat more” now that she is exercising. This confuses Sophie, because she is eating well across the day and isn’t hungry. But she trusts her friend and starts eating an additional 200 calories every day, the amount of energy she has calculated that she is burning. She notices that the rate of her weight-loss slows.

We know from the literature that consuming 1.2-2g of protein per kg of body weight is adequate to achieve gains in lean tissue in individuals partaking in moderate intensity resistance training three to four times a week. So, if we are seeking weight-loss and exercising moderately, 0.8-1.0g of protein per kg or body weight (the recommended XYZ for adults aged 18-69) is more than appropriate. It is also recommended to consume ~20g protein in combination with a complex carbohydrate 60-90 minutes before or after exercising, and to spread the remainder of your protein intake evenly across the day, every 3-4 hours, with no additional energy required to achieve sustainable weight-loss.

So where does this leave Suzie, Steve and Sophie?

• Well, in Suzie’s case we would encourage her to focus on her nutrition before and after her workout. We would suggest she aim to consume something small, with easily digested carbohydrate before her workout, and then to focus on eating regular meals throughout the remainder of her day.
• For Steve, who is happily at his goal weight and seeking improved performance during his cycles on the weekend, it would be very appropriate to assess how much energy was burnt and to “eat back” these calories in an appropriate manner.
• Concerning Sophie, who is at the start of her weight-loss journey and is happily walking and performing some light resistance training without upset to her hunger / satiety, it would be inappropriate to “eat back” her those hard-earned calories. Better they are saved for a special occasion!

If you need a little extra help finding a healthy balance for you, consider seeking the help of an Accredited Practising Dietitian for tailored advice. A healthier, happier you starts with just one phone call to 1800 567 348. Alternatively you can register your interest online.