Food Tracking And The Basic Maths Of Losing Weight

Food Tracking And The Basic Maths Of Losing Weight

A few weeks ago I set myself the challenge to shape up a little for summer. Nothing crazy, just positive changes in a healthy direction. The below tips are some of the basic principles I’ve used as direction.

Running image courtesy Shutterstock

The Simple Maths Of Losing Weight

Regardless of what you are or aren’t eating, there’s a fundamental formula at the heart of weight loss: you need to burn more energy than you consume. Calorie deficit. Conversely, if we take in more calories than our bodies use, the spare energy is stored as fat.

Next equation: A 7500 calorie deficit in a week equals 1kg weight loss. If you’re under about 100kg, it’s generally considered that 0.5kg per week is a healthy target for weight loss (1kg should really be your maximum). I can’t stress enough that it depends on your individual situation and health. If you’re unsure, check with your doctor or nutritionist.

Personally, I want to lose a couple of kilos over summer; maybe get down to 80kg. I need a deficit of 3750 calories per week, or about 535 calories a day.

The good news is that we burn calories just by getting up, brushing our teeth and going to work each day. How much is determined by our basal metabolic rate (BMR), and it depends on individual factors like your weight, height, age, gender and general level of activity.

I’m 35, 185cm, 83kg and exercise moderately. According to the NSW Government Health’s calculator at, I could eat about 2500 to 3000 calories a day and hold my current weight (with my current level of exercise also maintained). But to lose half a kilo each week, recommends I consume about 2000 to 2600 calories a day.

More: The Science Of Losing Belly Fat

Note: The calculator reports figures in kilojoules. So divide your results by 4.2 to get calories as 1 calorie = 4.2 kilojoules.

Thankfully, modern trackers like the Fitbit handle all these sorts of calculations for you — and provide more personalised estimates for what you need to achieve to reach your goals, including how long it’ll take to reach them.

Food Tracking And The Basic Maths Of Losing Weight

Tracking Your Food

While a paper notepad will get the job done, an electronic fitness tracker will help to streamline the process. They also come with a host of additional features. I’m currently using a Fitbit, which includes the option to start a food plan. Tracking intake helps keep you mindful of not only what types of food you’re eating, but also how much and when. And for me, portion control is what I’ve often struggled with.

Food Tracking And The Basic Maths Of Losing Weight

I’ve also long been a big fan of MyFitnessPal, a dedicated calorie-counting app/website that has a crowed-sourced database with many Australian foods. MyFitnessPal syncs well with many fitness trackers on the market, which opens up further options. Once the integration is set up with a few clicks on the site, just exclusively log all food and activity through MyFitnessPal to avoid duplicate tracking.

Meanwhile, the Australian government has lots of great refresher information on dietary guidelines, and most of us are across the basics of healthy eating anyway, even if we tend to conveniently ignore/forget sometimes.

The 80/20 Rule


No, I’m not talking about the 40/20 start from Rugby League, or the ‘Pareto Principle’ where, in broad terms, 80 per cent of effects stem from 20 per cent of causes.

In a healthy eating sense, 80:20 refers to the philosophy that as long as you eat healthy 80 per cent of the time, you can indulge in your favourite treats 20 per cent of the time. In other words, cut yourself some slack and seek positive long-term eating adjustments, not crash diets. When losing weight, you need to eat a balanced diet to fuel your body, kick start your metabolism and minimise muscle loss.

Bonus round: You may also heard that losing weight is 80 per cent diet and 20 per cent exercise. The exact ratio is up for debate, but there is some essential truth there.

Fitness Tests


As your fitness progresses and your confidence grows, you’ll hopefully be looking for a few new challenges to keep you motivated. That’s where new classes, sport and all sorts of fun stuff comes in. You might even create a friend network on Fitbit and challenge each other for most steps to earn badges.

One new area I’ve been looking at lately: fitness tests. Sites like and TopEndSports are fantastic resources to learn about everything from beep tests for cardio (download an app and head down the park!) to your maximum weight reps to your v02 max aerobic capabilities.

You’ll even find the AFL reaction time test. Now that’s a challenge!

So what happens to all the fat once you lose it? Apparently most of it goes into thin air

This story originally appeared on Gizmodo.


  • A lot of people always claim you should do more exercise rather than diet, which is, in part, true. However, exercise itself will never burn that many extra calories over sitting still. Of course, the extra muscle will assist your calorie burn, but still, it’s only giving you that extra edge, rather than a solution itself.

    Eat to adjust your weight, exercise to adjust your composition.

    • Er, yes. Exercise burns a LOT more calories than sitting still…

      When I do half-marathon distance runs (around an 1h 30 mins on a good day) at 82kgs, I burn anywhere from 2700 – 2800 calories.

      Sit still for an hour and a half and I would be quite surprised if you burn 2700 – 2800 calories. If we did, there wouldn’t be any obesity epidemic…

      • As an 82kg male your BRM is at least 2500 kcal. Assuming you do 1 half marathon a week (unless you’re an elite athlete), that’s about 17500 kcal a week in and 2750 out, or roughly 15% – like most people, I’m sure you eat a bit more on race day, pushing you closer to 10%. A good diet starts around 20% calorie restriction, so who wins?

        • you need to add the half marathon and his BMR x7 together to work out his weekly “out” calories. BMR = basal metabolic rate = how many calories you burn a day doing nothing but continuing to live. so it will be 17500 from BMR/staying alive and 2750 from the marathon.

          i lost weight eating KFC for dinner basically every weeknight night (other delicious food for dinner on the weekends) for a month by getting scientific with my calories in/out. i’m confident that if i didn’t play a really active sport 2x a week during this period i wouldn’t have generated the calorie deficit to achieve this.

        • Wasn’t debating the maths of losing weight…

          Only the maths of the difference in calories burnt between sitting still and getting up and exercising…

          The difference is enormous…

          For the record, I rarely run a half marathon distance only once per week, in fact I haven’t run that far since August, but your calorie burning ramps up when you do 35-40kays per week spread across 3-4 runs.

          Suffice to say I am lucky in that I am relatively able to eat as I wish from a calorie POV because of it.

          • That’s kinda my point.

            I’m not saying you should sit still – you’ve gotta be active, but regular exercise is not going to beat a good diet. Especially when people have a reward mindset and eat a fat piece of cake because they went to the gym in the morning – BOOM! calories burnt are back on.

      • For those of us who aren’t doing half marathons though…

        I burn approx 220 calories going for an hours walk, 100 calories from half an hour of weight lifting, and a little over 300 calories from half an hours swimming or boxing.

        Now, there’s 100 calories in a Tim Tam, about 115 calories in 30g of cheese, and about 150 calories in two slices of bread.

        Given that my TDEE is less than 1550 cals per day, it’s a LOT easier for me to just forgo the TIm Tams, and swap out a sandwich for a salad, than it is to walk for an hour and lift weights for 30 minutes.


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