Kung Fit Calorie and Macronutrient Calculator
For years I’ve used calorie and macronutrient calculators that didn’t use up to date science. The result was that I would have to manually edit the nutrition information they gave me to get the best targets for my needs. I finally decided it was about time I did something about it. After pooling my knowledge on nutrition and doing a few deep dives into various aspects of weight loss and muscle building, I’ve created what just might be the most scientifically backed calculator on the internet.
It’s in a spreadsheet which you can download here: Kung Fit Calorie Calculator (this is a direct download link for an Excel file. Once downloaded and opened make sure you click “enable editing” along the top to start entering your details).
Whenever you get nutrition advice, remember that we are all individuals with different needs, health conditions etc. Whilst I stand by the information in this calculator as a tool for people looking to combine nutrition and exercise to achieve their goals, you need to take your personal situation into account and use this at your own discretion. If in doubt consult with your doctor or dietitian.
Keep reading to find out how to use the calculator, and if you want to know more about nutrition in general and the information that went into the tool you can find that after the instructions.
Now despite having invested a lot of time into this, there’s always more evidence to be read and new studies coming out all the time, but at some point you have to call something done. I spent 9 years working on my PhD in my spare time, and I don’t want to do that again! Nevertheless I want this tool to be the best it can be, so if you find any good studies that you think can inform this, let me know- Contact
One thing which makes any science based tool better is plenty of good data. So if you make use of the Kung Fit Calorie Calculator, consistently log your food and track your weight and body fat %, I’d love it if you shared your data with me. I’ll keep all data anonymously and if I get enough it could end up being a really valuable study into the effects of nutrition and exercise on body composition.
How to Use the Calculator
There are two options in the calculator, a basic one and a more advanced one, depending on how involved you want to be. They operate very similarly, with just a few extra features for the latter.
Once you have downloaded (or made your own copy) under the File menu in the link above, enter your sex, age, height in centimetres, weight in kilograms and your body fat percentage. The Sex and Fat Percentage boxes are drop downs, the others are free text boxes and require numerals rather than text (e.g. 33 not thirty three). If you normally use different measurements such as feet and lbs, just do a quick conversion by typing X lbs to kg into your search engine.
Fat percentage is the most difficult part, but don’t worry about being really accurate, no need to go out and get a DEXA scan! Just use body fat scales, skin fold callipers or even google body fat % images and compare yourself to what you see. A rough ballpark is good enough for most people.
Next, select your goal from the drop down box. This is the most important part of the whole process. Do you want to build muscle, lose fat, or even just maintain a healthy weight? You can find out more about each goal below.
The final step of the calculator is to select how much exercise you do each week. This should include only things of at least a moderate intensity, such as a brisk walk and above. Don’t count a slow stroll or getting up from the desk to make a coffee!
The calculator will now have worked out your caloric and macronutrient needs. The key things to pay attention to are the Targets for your goals boxes.
These numbers are all adjusted according to your details and goals. The top line, kcal, shows how many calories you should be eating each day. The next three lines break down the three macronutrients (macros), protein, fat and carbohydrates and give a percentage of your calories that each represents. This makes it easy to add these numbers into a food tracking app like MyFitnessPal. I’ve no association with them, but I use the app everyday and it works pretty well. The free version only lets you add in a % in multiples of 5, but a few % off of what the calculator recommends is not a huge problem.
You might think that the protein is pretty high, and much more than you are used to. This will help support your progress towards your goals though, whether they be to lose weight of build muscle. Protein is necessary for building and maintaining muscle and it helps keep you feeling full, so make sure you get plenty.
Fat and Carbohydrates are on a sliding scale. You will notice that there is a minimum and maximum fat. These are based on recommended healthy limits, so avoid going outside these limits. Within that though you can chose an amount to suit your preferred diet, and energy levels. Carbs simply fill in what is left. If in doubt, remember that 1g of fat is 9 calories, and 1g of carbs is 4 calories. If you wanted 30% fat calories from 2000, you would do the following: 2000*0.3=600 calories, 600/9=66.7g of fat.
If whilst looking to lose weight you find you are low on energy, try increasing your carbs a bit, potentially adding in a little more activity to allow you to eat more, rather than sacrificing protein.
Stick to these numbers and you will be well on your way to your goal. The graphs and final two tables in the calculator give a prediction on your progress towards your goal. For weight loss, these only extend to 12 weeks. This is the maximum length of time you should look to lose weight for (if your goal is building muscle you can of course go longer than this). If you have not successfully dieted and kept the weight off before 6-9 weeks would be better. After this time you should do a maintenance phase as long as the diet was. This will help your body adjust to your new weight, and avoid your metabolism slowing. This helps to prevent the weight rushing back on. Once your diet is over, recalculate your caloric needs for maintaining your weight.
No matter what your goal you should periodically update your calculator to take account of your new weight and body composition. This will not only help to keep you progressing, but it will also help to keep the predicted progress accurate. If you lose 5kg for example, your required calories and your rate of fat loss will have changed.
Advantages and Disadvantages of Calorie Calculating
Using a food tracking app will allow you to scan barcodes for your food, or add in manually food you have made yourself. Make sure you weigh everything you eat, unless you are consuming a full packet of something. This will allow you to match your intake to your goals. Don’t just focus on the calories and macros though, try to eat minimally processed foods and plenty of fruit and veg. This will support your body and help you to feel full, don’t let the number blind you to the quality of the food you are eating.
I advise planning ahead at the start of each day, that way you can adjust as needed to make sure you are on track. It is OK if plans change, and you end up with a pizza instead every now and then, but having a plan sets you on the path to success.
Calorie counting and macronutrient tracking can be tough, but if you stick with it, even if you aren’t always on target, you’ll make progress. It will also help you to become more aware of what is in the food you are eating, which can carry over to a long term positive relationship with food that can support a healthy lifestyle.
The main thing is to not stress, do the best you can and try to have more good days than bad. A blow out birthday celebration can always be countered with a slightly more frugal week afterwards.
The Advanced Calculator
The advanced calculator operates in much the same way, but has two changes. Firstly you can select how many years you have been regularly doing resistance training. This will impact your predicted results if you are looking to build muscle.
Secondly, rather than just selecting a general activity level, you can enter your specific weekly exercise. Select the exercise from the drop down list, enter how many hours you spend doing it each week and it will estimate the calories you burn, based on your details. The weekly total will then be factored into your daily calorie allowance. So the more you work out, the more you can eat!
Not every exercise is in there, but it is a pretty good range, and of course, it even includes Kung Fu!
These numbers might not quite tally with what your fitness tracker says, but don’t worry. These are, as ever averages across a population, and for some scientific reasons you can read more about below, are deliberately slightly lower than you might expect.
Goals
There are five distinct goals for you to chose from, lose weight, maintain weight, build muscle, maintain muscle and lose fat and gain muscle and lose fat.
These might commonly be referred to as diet/cut, maintenance, bulk and body recomposition. The predictions provided are estimates, and your exact progress will depend on your adherence to the nutrition targets, your exercise, your metabolism and your genetics.
Lose Weight
If you’re looking to lose a lot of weight, or lose weight quickly, this is the goal for you. For most people I would recommend choosing maintain muscle and lose fat instead, as this goal is more likely to result in losing muscle. Muscle is not only useful for lifting heavy things, it increases your metabolism, meaning you can eat more and are more likely to keep that weight off. Sometimes more rapid weight loss is in order though.
Aim for the lower end of the scale such as losing 0.5% of body weight a week if you are relatively new to calorie counting diets. 1% should really be your maximum, and best kept for those who have successfully dieted before (stuck to the diet and kept the weight off afterwards).
Remember to recalculate if you lose more than 5kg, and to start with a 6-9 week diet, followed by the same amount of time at maintenance to allow your body to get used to the new weight, and for your metabolism to stabilise. It may seem slower, but in the long run, you will be far more successful at keeping the weight off. Again, successful dieters could go up to 12 weeks in the future, but no longer.
For the advanced calculator you can chose a specific calorie deficit instead of a specific weight loss.
Maintain Weight- No/Minimal Exercise
Does what it says on the tin. Your maintenance calories, with macronutrient distributions which allow for a more decadent diet! If you are not doing resistance exercise, you need less protein to fuel your muscles. You can still add exercise which will increase your calorie allowance, but if you’re going to do resistance exercise, pick the goal below.
Gain Muscle Lose Fat
Also maintenance calories, but with more protein to support muscle growth. This will result in a small level of fat loss if you are not particularly lean, due to the energy required to build muscle. You could use this for your maintenance phase/default nutrition.
Maintain Muscle Lose Fat
A slight caloric deficit which will allow you to lose weight. Combining higher protein intake with resistance exercise will encourage your body to maintain muscle whilst using fat for extra energy. If you are already very lean you are more likely to lose muscle with this goa.
Build Muscle
This goal puts you into a caloric surplus to maximise the chance of gaining muscle. The higher the surplus more likely it is that you will gain more muscle. Not all of this energy goes into muscle building though, and you will likely gain some fat too. The higher the surplus, the more fat you will gain.
Bonus Tips
Time for a few extra bonus tips!
1) Make sure you drink plenty. Hydration is very important in itself, but often when you think you are hungry, you are actually thirsty. A lot of people have a weak thirst reflex and find it difficult to tell the difference. If you are struggling with hunger, have a large glass of water and wait 10 minutes, If you’re still hungry, go for it.
2) Don’t drink your calories. Sugary drinks aren’t good for you for many reasons, but they also mean you can eat less, and they don’t fill you up very much. So if you want something sweet and fizzy, go for a zero sugar version instead.
3) Chew, chew and chew again. Eat your food more slowly, consciously chewing each mouthful as much as possible does two things. It helps with digestion, which will make you feel less bloated, and it gives your brain time to process signals from your stomach that it is full (for some reason this takes a while, possibly because we used to eat what we could get when we could get it). This means that you might not need to eat as much as you thought. If you’re looking to build muscle, you’re going to need to hit those numbers, but for most of us, most of the time eating too little isn’t much of a problem.
4) When tracking your progress use a combination of two tracking methods from weight, progress pictures and tape measurements. This will give you a good understanding of where you are at. If you are using weight or tape measurements, remember that what you eat and drink, how bloated you feel, how much salt you have had, whether you have been to the loo and more all have an effect on the readings. So don’t worry about each individual fluctuation. Measure each day, and then take an average for the week. Compare these averages over time to see your progress.
5) Be more active throughout the day. Exercise won’t outdo a bad diet, but keeping moving as much as you can will have a positive impact on calories burned and will reduce feelings of boredom and hunger, helping you stay on track.
Assumptions and Key Research
For those of you interested in what goes into this calculator, here are some of the assumptions and relevant scientific studies that I used in building it. Plenty more research went into this, but not every study ends up directly relevant.
Basal Metabolic Rate
This calculator uses the Mifflin-St Jeor model for calculating your BMR. This is essentially how much energy your body needs to function properly before you do any form of activity. If you slept all day and didn’t move an inch, this is approximately how many calories you would burn. The Mifflin-St Jeor model is an average based on looking at a group of people. Each individual will sit across a range that goes above and below this; we are all different. This model has been shown to be more accurate in the modern population than the older Harris Benedict equation.
For very lean people the Katch-McArdle model can be more accurate, but it requires an accurate body fat %, which can be very hard to get. In practice the numbers vary only by a small amount, giving about 6% more calories to very lean people.
Total Daily Energy Expenditure
The amount of activity we do, even just getting up to go grab food now and then, must then be added on top of the BMR to work out our TDEE. This is how much we would need to eat in order to maintain our weight. Eating less will result in weight loss, eating more will result in weight gain. The basic calculator uses standard numbers for different activity levels taken from a number of country guidelines. The advanced calculator takes into account your incidental daily activity (getting up round the house, generally living etc. sometimes known as NEAT), and adds on top any exercise that you include.
Weight Loss
Unfortunately not all weight that is lost is fat, some of it is muscle too. In order to work out how much of a calorie deficit is needed to lose a certain amount of weight a calculation can be applied. A study by Hall (2008) has shown that the calculation normally used (3500kcal per 1lb) does not accurately reflect real world data because the levels of fat vs muscle in a person will have an effect on the proportions of each which are lost when on a diet. A very lean person losing weight will have a smaller proportion of it as fat than someone who is less lean. From a biological perspective, this makes sense, our body will look to preserve the most scarce resource. This is why those last bits of fat are the hardest to lose! Also bear in mind that how much weight you lose will also depend on your metabolism, along with nutrition, exercise and specific body make up. Weight lost is therefore an estimate.
Hall’s study determined how much energy was required per kilogram of weight loss, for people losing 5kg, and starting at different fat levels. From this we can approximate what proportion of this loss is muscle vs fat from the calorific value of each. This is another reason why it is important to recalculate should you lose more than 5kg. Bear in mind this predicted fat loss is an estimate based on an estimate of weight loss.
If you are on the gain/maintain muscle lose fat goals, the assumption has been made that you have enough starting fat, are doing enough resistance exercise and are eating the recommended amount of protein to minimise the chance of muscle loss. If you are already very lean this so called “body recomposition” will be much harder.
Body Fat and Fat-Free Mass Interrelationships
What is the Required Energy Deficit per unit Weight Loss?
Protein Intake
Protein intake is normally suggested at 1-1.5g per lb of body weight (or 2.2-3.3g per kg), but due to differences is body composition, i.e. the amount of muscle, using lean body mass is a much better approach for most. A number of recommendations suggest protein intake should be 15% of calories for the general population. This calculator will not give results less than this. Such recommendations are for the average person; someone looking to maintain weight and who are not very active. A higher protein intake helps you to feel full and can help maintain and build muscle, promoting weight loss to be fat.
For those with a high body fat, looking to maintain or build muscle, protein intake is set at 2.2g per kg. For leaner individuals the protein intake is increased up to 3.1g per kg of lean body mass as studies have shown that this level of intake has an increased chance of supporting muscle growth/maintenance. Two that stand out are listed below. The studies used “athletes” or “trained” individuals, but this only means that they had been training for 6 months, so the studies should be applicable for anyone who is, or is looking to become active.
Protein, weight management, and satiety
Fat and Carb Intake
Fat vs carbohydrate intake can be a very persona thing. Some people will feel better on more fats, others on more carbs. However it is worth noting that carbohydrates are really important for fuelling your workouts, so you don’t want to cut them too low, or you will feel lethargic.
Fat meanwhile has some clearly defined boundaries. Too much fat has been shown repeatedly to be bad for you, especially saturated and trans fats, and a large fat diet will often lead to an increase in these too. Equally there is a minimum amount of fat which your body requires in order to function properly and maintain a good hormonal balance. The World Health Organisation recommends that fat constitutes no less than 20% and no more than 35% of your daily calorie intake. They have a broad range of guidance documents and studies which they have commissioned. Their most up to date general guidance can be found on their website here: https://www.who.int/news-room/fact-sheets/detail/healthy-diet
Muscle Gain
The muscle gain predictions are averages based on a range of studies looking at different periods of a resistance training programme. It assumes that you are not taking any performance enhancing substances and are doing regular intense resistance training. The studies looked at different nutrition and training regimes, however there are few long term studies. Therefore after the first few months of training expected gains are in line with industry accepted norms.
The first 20 weeks of resistance training see gains of up to 0.2% per day, afterwards the rate drops to one quarter of this. This is simplified and averaged out over your first year of resistance training. There is no variation in age or gender, and the calculator assumes that your starting muscle mass is in line with the average for men and women as a ratio to weight.
Being in a calorie surplus is not necessary for building muscle, but it helps. If you are very lean then you will need a calorie surplus; building muscle requires energy! You may gain more, you may gain less, depending on your nutrition, training and genetics. This means that you may even gain muscle whilst in a calorie deficit, for example in the maintain muscle lose fat goal. The larger the calorie surplus, the more likely it is that your body will devote energy to building muscle, but on the flip side the more likely you are to gain fat as well. This is factored in to the different bulk options. After you have been training for a few years your rate of muscle gain will likely be less than predicted here as you reach your genetic potential.
Skeletal muscle mass and distribution in 468 men and women aged 18–88 yr
Muscle size responses to strength training in young and older men and women - PubMed (nih.gov)
Calories Burned During Exercise
The number of calories burned during exercise will depend on your weight body make up and the intensity of the exercise. The advanced version of this calculator allows you to select different exercises with some options of intensities. The calories burned are taken from a range of sources, which have been cross referenced, and consider people in different weight categories; below 63kg, below 76kg, below 88kg and above 88kg. Individuals who are far below or above this range will burn fewer or more calories respectively.
Broskey et al (2021) found that the weight lost from increased activity was half of what was expected, likely due to behavioural changes caused by the increased intense activity (less incidental movement, fidgeting etc., greater body efficiency and possibly compensatory increased calorie intake.
The listed number of calories burned considers the knock on effect of exercise to non exercise activity thermogenesis (NEAT); essentially how much energy you burn from fidgeting, subconsciously moving, getting up to wander round the house etc. Increasing your exercise (and dropping your calories to a large degree) tends to reduce your body’s other movement in order to preserve extra calories.
Effect of Aerobic Exercise-induced Weight Loss on the Components of Daily Energy Expenditure
