I wanted to write a simplified, step-by-step guide to calculating calories and macros. Now, our bodies are a lot more complex than this, and this guide is definitely over-simplified. However, I hope it can serve as a starting point. If you follow the guide, then you will hopefully have diet you can follow for a few weeks which will likely work to some extent, and then after 2-3 weeks you can change it to make it more effective to suit your needs.
Table of Contents
- Step 0 – Weighing yourself and useful tools to measure progress
- Step 1 – Calculating Calories
- Step 2 – Calculating Protein intake
- Step 3 – Calculating Fat and Carb intake
- Step 4 – Fibre and Micronutrient intake
- Step 5 – Water intake
- Step 6 – Supplements (optional)
- Step 7 – Cheat days (optional)
- Step 8 – Make adjustments
- Instruction Summary
- Final Thoughts
0 – Weighing yourself and useful tools to measure progress
For calculating calories and macros you are going to need your bodyweight.
Your calories and macros will also be determined using rough estimates, meaning that you are very likely going to have to change your diet if it isn’t working, or to make it work better. This is more important – and therefore you are going to need to measure your bodyweight regularly in the same way each time – this means weighing yourself with your scales in the same place each time (recommended to be on a hard floor – not carpet!) at the same time each day whilst naked. First thing in the morning works best for most people. Weigh yourself to get your bodyweight to set up your diet, and then continue weighing yourself everyday in this same way.
You may also want to measure progress of muscle gain or fat loss. You can do this easily enough by taking a photo of yourself every 2-4 weeks and comparing them, or by measuring different body-parts each week. You will need 4-6 weeks of data to start results though – we are all about getting stronger slowly after all!
Summary: Weigh yourself naked with the scales on a hard surface to get your bodyweight. Then weigh yourself this same way at the same time every day (or every other day).
1 – Calculating Calories
Your calories will be the total amount of food you need to eat each day. First of all, you need to work out how many you need to eat to stay the same bodyweight.
This is done in two stages:
Stage 1 – Take your bodyweight in lb, and multiply it by 10.
Stage 2 – Take this new number, and multiply it by the activity modifier below:
| Activity Level | Activity Modifier |
| Inactive Job/Lifestyle | 1.4 |
| Slightly Active Job/Lifestyle | 1.6 |
| Active Job/Lifestyle | 1.8 |
| Very Active Job/Lifestyle | 2.0 |
Example: Athlete weighs 180lbs, and works in a desk job.
Stage 1 – 180lb x 10 = 1800.
Stage 2 – 1800 x 1.4 (Inactive Job/Lifestyle modifier from above) = 2520 calories per day
This figure is the amount of calories you will need to maintain your bodyweight whilst strength training several times per week. If your intention is to maintain weight, then move on to Step 2. If you want to gain weight or cut weight, then read on.
Gaining or Losing Weight
If you want to gain or lose weight, your going to have to increase or decrease the amount of calories you are eating. To bulk up and gain muscle (and also some fat along the way – unavoidable sadly), you will need to increase your calories. To lose weight and fat (you may also lose muscle – but not always) you will need to decrease your calories.
If you increase or decrease your calories by 500 per day (roughly 3,500 per week) then this will cause you to gain or lose 1lb of bodyweight a week. Generally, its best to recommend you gain or lose 0.5%-1% of your bodyweight per week, so you can do the math to figure out how many calories to add. Alternatively, the old school approach is to just add or subtract 300-500 calories per day from your daily calorie total. Both options work well.
To bulk or to cut?
This is where your personal preference comes in to it, but there are some good rules of thumb to follow:
Waist size
Your waist should be less than 37″ for men, and 31.5″ for women. Occasionally you may choose to exceed this towards the end of a bulk, but you are best to stay below this. To measure your waist size, measure your stomach at around the halfway point between the base of your ribs and the tip of your hips, and breathe out before measuring.
These recommendations are made by the NHS here: https://www.nhs.uk/live-well/healthy-weight/bmi-calculator/ – don’t both with the BMI calculator, just read the waist size section, the BMI calculator won’t work for people with a good amount of muscle on them.
Novice Athletes
Novice athletes can get a lot of strength fairly fast. Unless you need to cut due to a risk in health (see waist size), then I’d suggest maintaining weight or bulking if you are new to strength training, at least for the first 3-6 months.
Skinny-fat
If you have low amounts of muscle but also have a good amount of bodyfat, you are usually best of just maintaining for a while, and then reassessing later on to see if you want to bulk or cut. Changing your body-shape if you are skinny-fat is always going to be painful initially. You can bulk to get more muscle whilst getting fatter, or you can cut to lose fat but you’ll look even skinnier then. Maintaining is best generally, but you may still need to do a short bulk or cut afterwards which may not be too pleasant, but it will get better!
Summary: Bodyweight x 10 x activity multiplier = Maintenance Calorie amount. Add or subtract 300-500 calories from this to gain or lose weight.
2 – Calculating Protein Intake
This is the easiest part of calculating calories and macros.
For every 1lb of bodyweight, eat 1g of protein per day.
Example: 180lb athlete will eat 180g protein per day
If you’ve never been on a high-protein diet before this will seem like a lot, but protein is key to muscle gain and retention, and is why we are calculating it separately.
Why 1g per lb of bodyweight? To keep it simple. You’ll see different recommendations everywhere – some will say 0.6g per lb, others 0.8g per lb, others will use lean body mass as a reference, old-school bodybuilding “bro-science” used to dictate 1g per lb of body. Realistically my recommendation is likely overestimating your protein intake, but eating more protein than you need (as long as its not an excessive amount) is completely fine, and overshooting is better than undershooting.
Summary: 1g protein per lb of bodyweight per day.
3 – Calculating Fat and Carb Intake
To calculate your fat and carb intake, you need to figure out how many calories you have to dedicate to them. To do this, you need to figure out how many calories were taken up by protein.
1g Protein = 4 Calories
1g Carb = 4 Calories
1g Fat = 9 Calories
Take you protein intake and multiply it by 4. This is the amount of calories dedicated to protein. Subtract this from your total amount of calories, and you’ll know how many calories you can dedicate to fat and carb.
Example: Athlete needs to eat 3000 calories per day. They are eating 220g of protein per day.
220 x 4 = 880 Calories from protein.
3000 Calories per day – 880 Calories from protein = 2120 Calories left for Carbs and Fat.
Now you have two options to calculate your Carb and Fat intake.
Option 1 – Common Sense Option
This is the option which is easiest to go for, and is certainly a viable option. This option involves simply eating what you like to fill up the remaining calories, making sure you stick to your calorie quota. The split will just be determined by what you want to eat. Some of these calories will potentially go into additional protein, but as long as its not excessive amounts then going over your protein won’t make a difference.
This is the common sense option, because you just use your common sense to determine what you are eating to make sure it is appropriate, and for most people this is perfectly acceptable.
Option 2 – Predefined Split
The second option is to work out how much fat and carbs you should have and base your diet around this. Word of advice: don’t focus hugely on this split, if you go over your carbs or over on your fat, that is fine, as long as your calorie intake is correct and your protein intake isn’t lower than it needs to be. There is a lot of leeway available.
I recommend taking the remaining calories (Total Calories – Protein Calories) and setting aside 25% of them for fat intake. So take the remaining calories and divide it by 4. This is the number of calories you have for fat. There are 9 calories in 1g of fat, so take this number of calories and divide it by 9 to get the grams of fat each day.
Example: Athlete has 2120 calories to split between Carbs and Fat.
2120 ÷ 4 = 530 Calories for fat
530 Calories ÷ 9 = 59g fat per day.
Now, the remaining amount of calories will go on carbs. To work out how many grams of carbs this will be, divide the remaining calories by 4.
Example: Athlete has 2120 calories to split between Carbs and Fat. Fat is 530 Calories.
2120 – 530 = 1590 Calories for Carbs
1590 Calories ÷ 4 = 398g Carb per day.
Adjusting Carb and Fat split
The split I recommended of 25% of the remaining calories going towards fat should be fine for most people. However, you can try to increase this to 30% of the remaining calories towards fat if you like, maybe even try going up to 40% for fat. Simply try it for 3-4 weeks and see how it feels, and see how it affects your weight and body composition.
Step 4 – Fibre and Micronutrient Intake
Getting a good amount of fibre from food means you are probably eating a lot of healthy food options. Likewise, getting a good amount of Micronutrients means you are eating a lot of fruit and veg. Both of these will mean you have a healthy diet.
A good ballpark figure for fibre intake is 38g for the average man, and 25g for the average woman. I’d suggest aiming for this amount each day, but not being concerned if you go over.
For Micronutrients, the easiest recommendation is to try to eat a good amount of fruit and veg. I’d suggest 3 servings of fruit, and 3 servings of veg everyday. Again, if you go over, this is fine. Try to aim for 6 total servings, but if you only get 4-5 don’t worry too much. To know what is classed as a serving or what counts towards this goal, I suggest you check out the NHS website here: https://www.nhs.uk/live-well/eat-well/5-a-day/5-a-day-what-counts/
Step 5 – Water Intake
To calculate your water intake, there are two formulas you can use:
Half your bodyweight in lb in Fluid Ounce.
Example: Athlete weighs 200lb. Half their bodyweight is 100lb. Therefore they will drink 100 fluid ounces of water per day.
Bodyweight in kg x 33 = water intake in ml
Example: Athlete weighs 100kg. 100kg x 33 = 3300ml per day.
Step 6 – Supplements
If your diet is up to scratch, you will rarely need additional supplements. Therefore, this recommendation is very simple:
Take 5g of Creatine per day. Best option is Creatine Monohydrate. Don’t worry about when you take it, once its in your system after a few weeks, the timing is irrelevant.
Step 7 – Cheat Days
If you want a cheat day (which is optional) then you have two options. You can simply increase the number of calories you are allowed one day per week, ideally to maintenance levels. You may not lose quite as much weight as usual, but the difference will be small.
The other option, is to increase one day per week to your maintenance calories, and then reduce the other days accordingly. An example of how to do this:
Calories to maintain weight: 3000. Calories to lose weight: 2500.
One day a week per week will be 3000 calories. The additional 500 calories you eat will be split between the remaining 6 days per week.
500 calories ÷ 6 days = 83 calories per day.
Normal daily allowance = 2500 calories – 83 = 2417 Calories per day.
Therefore, the cheat day will be 3000 calories, the remaining days will be 2417 calories per day.
This is optional, but some people find it useful to maintain compliance.
Step 8 – Make Adjustments
You’ve set up your diet. Now you need to stick with it for at least two weeks. During this time, I suggest you track your bodyweight numerous times per week, and track your daily calories, protein, carb and fat intake.
To do this, as before you need to weigh yourself at the same time each day, with the scales on a hard flat floor while your wearing no clothes. You can track your calories manually, or you can use an app. I recommend MyFitnessPal. It has recently added some features behind a paywall, but it still seems like the best option out there.
Now, after two weeks you won’t see any difference, but you can take an average of your weight for week 1, and an average weight for week 2 to see if you are achieving your goals. If you aren’t then add or subtract 300 calories from your daily calorie intake, making the appropriate adjustments to your fat and carb intake and then retest after another week.
Instruction Summary
Here’s a quick summary of calculating your diet for future reference:
- Take your bodyweight in lb, multiply it by the activity multiplier in Step 1 to get your maintenance calories.
- If you want to gain weight, add 300-500 calories to your maintenance calories. To lose weight, subtract 300-500 calories. This is your daily calorie goal. Try to keep your waist size below 37″ for men, and 31.5″ for women.
- Eat 1g of protein for every 1lb of bodyweight you weigh.
- Multiply protein intake (in grams) by 4 to get calories from protein.
- Subtract calories from protein from your daily calorie goal.
- Take 25% of the remaining calories. These are your calories for fat. Divide it this by 9 to get the amount of fat in grams.
- Take all the remaining calories and divide it by 4. This is your amount of carbs in grams.
- Each day eat 38g fibre for men, 25g for women.
- Eat 3 servings of fruit and 3 servings of veg per day.
- Take half your bodyweight (in lb) and that is how many fluid ounces of water you should aim to drink per day.
- Take 5g Creatine Monohydrate each day.
- If you want a cheat day, make one day your maintenance calories.
Calculating Calories and Macros: Final Thoughts
This was a simplified guide to calculating calories and macros. A lot in the guide was oversimplified, however realistically it really doesn’t need to be much more complicated. You can go deep down the rabbit hole when looking at the amount of calories to eat, how much to cut by, carb and flat splits etc., but even then this will be inaccurate when you first start. That is where step 8 – make adjustments comes in. Whatever you work out will need some altering, but after the first 2-3 weeks on your diet you should know how much to eat.
The most important thing you can do, is figure out how many calories you need to eat, eat enough protein, and eat a good amount of fruit and veg per day. The rest will fall in place for most people. Try not to overthink your diet.
If you do want to learn more about planning nutrition, or if you want to look at specifics like peaking for competitions etc., then I suggest you check out the Muscle and Strength Pyramid: Nutrition, which you can see an in-depth review for here.