Following a keto diet means paying attention to your macros so you stay in ketosis. While you can find a few online calculators for this, it’s more than possible to calculate your optimal ketogenic macronutrients without one.
This article will break down, step by step, how you can determine your own personal needs regarding calories and macros on a ketogenic diet. Here are the things we’ll calculate:
#1 Your Basal Metabolic Rate (BMR)
This is the number of calories your body needs just to support its vital functions (without taking into account extra energy needed for things like exercise). This is important because the more of you there is, the more energy (calories) you need to support daily processes.
While it’s tough to get an EXACT calculation of basal metabolic rate, we can get really close by using the Harris-Benedict equation below. (If you’re in an area that uses metric, the Mifflin-St. Jeor equation will be easiest for you.)
- BMR for men = 66 + (6.2 x Weight in pounds) + (12.7 x Height in inches) – (6.76 x Age)
- BMR for women = 655.1 + (4.35 x Weight in pounds) + (4.7 x Height in inches) – (4.7 x Age)
Let’s break each of these down a little more.
Calculating Height and Weight
Measure your weight in pounds. This step is easy.
Calculate your height in inches. Multiple the feet by 12, then add the additional inches. For example, someone 5’ 8” would be a total of 68 inches tall.
Since muscle mass gradually declines as we go past age 30, BMR decreases over time as well. That’s why age is factored into this equation.
Since body composition is typically a little different between men and women, gender factors into the equation.
So, again, use these equations to get your basal metabolic rate:
- BMR for men = 66 + (6.2 x Weight) + (12.7 x Height) – (6.76 x Age)
- BMR for women = 655.1 + (4.35 x Weight) + (4.7 x Height) – (4.7 x Age)
Now, move on to #2 below to get your total caloric expenditure.
#2 Your Total Daily Energy Expenditure (TDEE)
Along with BMR, we also have to account for daily activity you do and add that to your BMR. This will let us know your total daily energy expenditure (TDEE), which matters for calculating calories and macros.
Use these numbers as a guide:
- 1.2: Little to no exercise
- 1.375: Light exercise 1-3 days per week
- 1.55: Moderate exercise 3-5 days per week
- 1.725: Hard exercise 6-7 days per week
- 1.9: Very intense exercise
Remember: exercise can include what you do for your career, such as a job that’s very physically demanding
Using the number that best matches you, multiple that number by the BMR number you calculated above. For example, a woman with a BMR of 1500 who does moderate exercise would multiply 1500 by 1.55 to get their total daily calorie expenditure, 2,325.
#3 Your Body Fat Percentage and Lean Mass
Measuring your body fat percentage is important for calculating how much lean body mass you have and how much protein you’ll need to maintain muscles.
You can measure body fat in a few different ways:
- DEXA scan: This is the most accurate method but takes the most time and money. It’s a type of x-ray that measures your bone mineral density and can give you a good reading of your body fat percentage.
- Skinfold calipers: This is probably the most recommended method. Most gyms and doctor offices will have these, or you can purchase them yourself.
- Body measurements: This involves using a measuring tape to get the width of your neck, hips, and waist to estimate body fat composition. While not the most accurate, it can give you a good idea.
- Visual estimates: If not able to do the above methods,you can estimate body fat percentage visually. You can use a guide like this to do so.
Once you know your body fat percentage, you can also determine your lean body mass. For example, someone who weighs 150 pounds and is 25% body fat, we can figure out their body fat in pounds:
150 pounds x .25 = 37.5 pounds of body fat.
To get lean body mass, we would do this:
150 pounds – 37.5 pounds of fat = 112.5 pounds of lean body mass.
Whatever your number is, we’ll be using it below when calculating protein needs.
#4 Your Goals
If you’re not looking to change your weight, you can skip this step.
If you want to lose weight, you’ll need to be in a deficit each day. A reduction of 10-20% of calories is usually a good range to start with for weight loss. To reduce by 10%, multiple your total calorie expenditure by 0.10, then subtract that amount from your total calories. This is the max amount of calories you’ll want to want to consume each day.
If you feel like you can go lower than that, feel free to increase the percentage—but it’s not recommended to go above a deficit of 30% each day long-term.
If you want to build lean muscle, you’ll need to have a surplus of calories each day. 5-10% of total calories is a good range for putting on muscle. Start by multiplying your total calorie expenditure by 0.05, then add that number to your total calorie burn. This is your daily calorie count.
#5 Your Carb Count
On the ketogenic diet, carbohydrates usually only make up 5-10% of total calories. For most people, that’s around 20-50 grams per day.
Take your total calories from #2 (or #1 if you are maintaining your weight) and times it by 0.05 to get your 5% of calories number, then divide that by 4.
Then, take your total calories times 0.10 to see what 10% of calories is, and divide that by 4 to get grams. You’ll want to keep your carb count within that range.
So, the formula is (TDEE x % of calories) / 4 = Grams of carbs per day.
For example, someone with a total caloric intake of 2,000 per day who wants to stay within 5-10% carbs from total calories (2000 x 0.05 or 0.10) would calculate between 100-200 calories from carbs, which is 25-50 grams of carbs per day.
#6 Your Protein Count
It’s important to keep protein count moderate on the ketogenic diet, so we want to make sure you get enough to maintain muscle, but not too much to affect ketosis. The percentage of total calories is usually between 20-25%.
If you’re someone who’s sedentary, a good rule of thumb is 0.6-0.8 grams of protein per pound of lean body mass (which we calculated in #2).
If you’re moderately or lightly active, stick with 0.8-1.0 grams per pound of lean body mass
If you lift weights, you’ll probably need to be in the 1.0-1.2 grams per pound of lean body mass range.
Use these ranges to determine your protein range, and start with the lower grams number. For example, a moderately active female who weighs 150 pounds and has 112.5 pounds of lean body mass will need 90-112.5 grams of protein per day. We then multiply that by 4 to calculate 360-450 calories from protein per day.
Multiply your total calorie expenditure by 0.20 and then 0.25 to make sure you calorie amounts from protein fit within that percentage.
#7 Your Fat Count
Fat on the keto diet should make up at least 70-80% of total calories. You can take the percentage of carbs and protein you fall into above, add them, then subtract from 100 to get a percentage from fat.
And there you go! You’ve just become your own keto calculator. This is all you need to estimate your macros on the ketogenic diet (as well as get an overview of your body mass and goals).
Take Home Message
Although these formulas can be helpful, there’s no guarantee they are 100% accurate. However, what’s most important here is that you have ranges to work with and can adjust as needed over time. If you’re new to keto, you’ll start to learn as time goes on what percentages and calorie amounts work best for your body on the ketogenic diet.