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How to calculate your maintenance calories


person tracking their food intake on their phone

Whether you're a seasoned fitness enthusiast or you're just starting on your fitness journey, understanding the fundamental concept of maintenance calories is crucial for achieving your goals.


Maintenance calories is the average amount of energy (measured in calories) that a person needs to consume (through food) to maintain their weight. With energy balance being the driver of body weight gain or loss, we can then infer the following:

  • If your weight remains stable over time, you are eating at your maintenance calories

  • If you're gradually gaining weight over time, you've been eating, on average, in a caloric surplus. More than your maintenance.

  • If you're losing weight, you've been eating in a caloric deficit.

I can hear you saying - but what about exercise's impact on body weight? Indeed exercise may play into the energy balance equation, aside from, or in addition to, food intake. But as you'll see in a moment, we factor in exercise to the calculation of maintenance calories, and generally speaking, exercise tends to contribute to energy output much less than we think, or would like.


Why Maintenance Calories Matters

Maintenance calories serves as the foundation upon which your entire diet plan is built.

Whether your goal is to bulk up with muscle or trim down with fat loss, managing your net energy balance is the cornerstone of your dietary strategy.


Bulking up requires a net calorie surplus of approximately 200-300 calories per day. Any more may be beyond what's required for muscle growth, and will then be added as additional body fat. Having a baseline to then calculate your target daily calorie intake is necessary.


Conversely losing body fat requires a net calorie deficit of approximately 500 calories per day (more wiggle room depending on the person). Too large a deficit may not only lead to body fat loss, but muscle loss too. Again a good reason to have a baseline to then establish target calories.


How to calculate your maintenance calories

There are 2 methods, which i'll discuss from easiest but with flaws, to more effort with greater accuracy.


Method #1 - Calorie Calculators

I use these calculators myself for clients, if Method #2 just isn't feasible, so it is a very good option. Essentially online calculators use popular formulas like the Katch McArdle and Harris Benedict which crunches the numbers based on your age, sex, height, body weight, and estimated physical activity level. The Flaws of online calculators

  • Body Fat Percentage Variability: One significant factor that impacts your resting metabolic rate is your body fat percentage. The more lean muscle you have, the more calories you burn. The Katch McArdle formula factors body fat percentage into the calculation, which is good for those who have established this figure, but unfortunately, calculating body fat percentage can be a challenge, and often not as accurate as we might hope.

  • Lifestyle and Activity Levels: Your daily activity level, which includes both your job and daily exercise, can significantly affect your total daily energy expenditure. The physical activity level (PAL) multipliers used by these calculators are often rough estimates and can be highly subjective and broad. For example, an option to select is "moderate exercise 2 to 3 times per week". One person's moderate may be another person's light. Not to mention that 2 days per week is 33% less than 3 days per week.

Circumvent the flaws

When using an online calorie calculator, after putting in the objective data (age, height etc), lean in the direction of your goal when selecting your physical activity level. For example if building muscle is your goal, and you think "moderate exercise 2-3 times per week" sounds like you, select the next one up, "hard exercise 4-5 times per week", for a higher "maintenance" to be provided. On the flip side, if your goal is fat loss and "moderate exercise 2 -3 times per week" sounds like you, select the next one down, "light exercise 1-2 times per week". This way a nutrition plan based on your "maintenance" calories, even if inaccurate, sways in the favour of your fat loss goal.


Auto-adjusting and refining

Let's be honest, you're only calculating your maintenance calories because you plan to follow a nutrition plan based off of these numbers. You may find a plan online or have a coach build one for you. Once you start following your nutrition plan you will need to track your weight to see if changes occur.


If your goal is fat loss, and weight is trending down, the estimated deficit is accurate. If weight loss is too fast (>1% body weight per week), the deficit is too deep, and adjustment should be made.


If your goal is muscle building, the change in weight should be expected to be slow. It likely shouldn't be detected in the first week, but over 2-3 weeks, weight should trend up slowly (1-2kg per month). If weight goes down, or doesn't budge you are in a deficit, or at your maintenance calories. You'd need to increase your calorie intake accordingly. If weight goes up quickly (>.5-1kg per week), you're likely over doing the surplus.



Method #2 - Tracking food intake

Now, let's explore a simpler and potentially more accurate method for calculating maintenance calories. This approach involves using your real-life data rather than relying on a calculator.


Assuming your body weight has been relatively stable over the past week or two (with no significant increase or decrease) and your activity level hasn't changed drastically, you can calculate your maintenance calories by following these steps:

  1. Keep a Food Diary: Log your daily food intake meticulously for about a week. Eat as you normally would, and make sure to include every food item, snack, beverage, oils and dressings that you consume. You can use MyFitness pal , EasyDietDiary, or any other tracking app.

  2. Calculate the Average: Once you have a week's worth of data, calculate the daily average calorie intake from your food diary.

  3. Use as Your Estimated Maintenance: This daily average represents your estimated calorie maintenance level. It's the number of calories you need to maintain your current weight.

  4. Track your weight (optional): Often, even when trying to eat normally while tracking, we can tend to eat in the direction of our goals. We'll subconsciously eat less or more, if our goal is fat loss or bulking, respectively. In conjunction with your food diary, weigh yourself each morning throughout the test week, and for another week beyond (I suggest you make daily weighing a habit anyway, for best long term results). After 2 weeks of weighing, average the 2nd week and subtract it from the average of the 1st week. If they're about the same, you are eating at maintenance. If it's positive, you're in a surplus, if it's negative, you're in a deficit.


A big benefit of Method #2, the tracking route, is that once you establish your maintenance calories, you can simply adjust quantities of your current diet, or make some simple food swaps that result in caloric intake changes. For example, for fat loss, if your usual breakfast is 200g full-fat yoghurt with oats and berries, you may reduce it to 150g and/or swap it out for low fat yoghurt. For bulking, if you usually eat 5 weetbix with 250ml of soy milk, you can adjust to 6 weetbix and 300ml of soy milk. This will adjust the intake by a margin, & you could then review your other meals to see what other tweaks can be made.


Summing up

Calculating maintenance calories is a fundamental step in achieving your fitness goals. While calorie calculators can be helpful, they have limitations that may lead to inaccuracies. The alternative method of using your real food intake data, provided your body weight is stable, offers a practical and potentially more accurate approach. Always remember that any calorie calculation method should serve as an estimated starting point. Continuously monitor your body weight and make adjustments as needed to stay on track with your fitness goals.


If you'd like to take the guess work out of your fat loss or muscle building plan, work with me to have customised training and nutrition plans built, that suit your lifestyle. Head on over to the coaching page for more info.

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