BMI and calorie calculator
Calculate the daily calorie intake to reach your Ideal BMI and Fat-Muscle profile. Learn how to get there efficiently.
The calorie intake calculator tool will tell you how many calories you need to eat per day to reach your ideal BMI.
This has become a hot topic in the diet world.
An accurate answer to this question is quite complex.
Proper calorie intake calculation requires measuring your O2 expenditure or CO2 release from breath and skin transpiration over a period of time.
But science has come up with formulas for calorie intake calculation, and while not as accurate, they are simpler.
The calorie intake calculation tool you have above is the state-of-the-art of what science can offer without a clinical exam.
It considers: gender, age, height, weight, body fat percentage and body type or constitution.
It also considers your overall level of physical activity.
The tool has two additional features.
It will calculate ideal bmi.
It will tell you what you need to do the reach your ideal body fat percentage.
For the science fans the article below explains in detail how these calculations are done.
Before we start, we offer 2 disclaimers:
1) You’ll get average results.
The calorie intake calculator will predict your Total Daily Energy Expenditure (TDEE) based on your average physical activity.
For accurate day to day calorie intake calculation we would also need to know the amount of exercise you do on a given day and the exercise you’ve done in the previous two days to account for the afterburn effect.
2) Calorie consumption is not a very good predictor of health neither counting calories a good way to lose weight.
A healthy life is not 80% nutrition and 20% exercise.
There are other very important ingredients such as sleep, being outdoors, and mitigating stress levels apart from nutrition and physical activity.
But even if we only focus on nutrition, calories don’t matter that much.
Recent studies show that the metabolic and hormonal effects that food has on our body are very important to our health.
A healthy diet is one where you eat what you need while maintaining a balanced nutrient intake.
A good diet is satisfying, diverse, rich in nutrients, contains no anti-nutrients and allows the body to regulate itself.
The Ketogenic Diet works extremely well in helping regulate your weight and energy level without paying attention to how many calories are consumed.
Avoid consuming nutrients that we’re not adapted to like sugar, alcohol and refined grains like flour.
They activate the hedonic reward system making us hungry even if we are full.
We firmly believe in the (scientifically backed) benefits of intermittent fasting, as well as hunger control mechanism for their own health benefits.   
If you are interested in learning more about what makes a diet healthy and how to reach your ideal weight in a sustainable way please read our guide for healthy living.
And now back to the science of calorie intake calculation:
The calorie intake calculation formula
CALCULATING CALORIES BURNED
The most widespread calculation of calories consumed in a day (TDEE) is based on this formula:
TDEE = (BMR + TEF + NEAT) + Ex + EPOC
- BMR is the basic metabolic rate (or what we burn if we lay in a bed and don’t move at all).
- TEF is the thermogenic effect of eating.
- NEAT is the energy expended in daily activity without any training.
- Ex is the energy spent during a training session.
- EPOC is the energy that continues to be spent after training sessions due to increased metabolism.
You can see that we have separated BMR, TEF and NEAT with a parenthesis.
This is because this part of the equation is simply the energy expended on a rest day.
Ex and EPOC is the energy expended because of training.
We will now discuss how we calculate each of these values and how we can know your ideal BMI.
BMR (Basic metabolic rate)
The best way to calculate your basal metabolism is by measuring the amount of oxygen consumed (or carbon dioxide generated). There are plenty of formulas that help us estimate this.
The calorie intake calculation tool above uses the two most accurate ones:
For people who are not very active we use the Mifflin-St Jeor equation :
Men: BMR = 9.99 x WEIGHT + 6.25 x HEIGHT – 4.92 x AGE + 5
Women: BMR = 9.99 x WEIGHT + 6.25 x HEIGHT – 4.92 x AGE – 161
- (Weight in kg, height in cm, age in years)
This equation appears to be 5% more accurate than the Harris-Benedict classic.
For highly trained athletes, it is more accurate to use the lean mass to calculate the basal metabolism.
In this case, we use the Katch-McArdle formula.
BMR = 370 + (21.6 x LBM)
Where LBM is the lean body mass:
LBM = WEIGHT x (1 – BODY FAT %)
How do we choose between these formulas?
We opted to use a combination of body fat %, BMI and activity level to determine this.
We consider someone an athlete if they are physically active, have a body fat percentage <= 10% in men and <= 15% in women and a higher than average BMI.
In this case, we use the Katch-McArdle formula to calculate your lean mass BMR.
TDEE AT REST (DAILY CALORIC EXPENDITURE IN A DAY WITHOUT TRAINING)
Most scientists use tables to calculate (BMR + TEF + NEAT) defined by the activity level of a person . This table measures an activity index based on the lifestyle of the person on a rest day:
|Activity level||Description||Activity Index|
|Sedentary||Person with a profession that involves sitting all day with very little walking.||1.2|
|Slightly Active||Person with a profession that involves sitting all day. He moves on foot (or bicycle) and do moderate physical activity not related to training. (1 hour per day of walking or moderate physical activity)||1.37|
|Active||Person with an active job and also travels on foot or do physical activity (not training) between 1:30 and 2 hours a day.||1.55|
|Very active||People with very active professions (construction, heavy industry) with a physical activity equivalent to running 15-20 km daily.||1.73|
|Professional athelete||Extremely active professions (woodcutter, miners, etc.) or professional athletes who train once or twice a day. Equivalent of running 22-35 km a day.||1.9|
As you can see in these tables, the biggest difference in index is in between sedentary and active lifestyles.
You should also be aware that this only includes the calorie consumption at rest.
To make things simple the calorie intake calculation tool only gives the first 3 levels assuming most of us are not that active.
With these calculations, we know how many calories a person consumes at rest (TDEE).
BMI (Body Mass Index) is calculated:
BMI = WEIGHT / HEIGHT^2
- WEIGHT in Kg
- HEIGHT in meters.
BMI is the measure nutritionist use to asses if someone is overweight or not as it considers the height of the person.
We can all agree that there is a difference between someone 5ft tall who weighs 200lbs and one 6ft tall with the same weight.
There are tables that tell you what is your ideal BMI based on gender.
However , BMI on its own is still a very limited measure. It does not account for higher or lower than average muscle/lean body weight.
People have different body types and this affects their ideal BMI.
Our calorie intake calculator tool corrects ideal BMI based on body type.
We measure wrist circumference to finger length ratio as a predictor of body type.
Based on clinic measurements we consider your ideal BMI:
- Average difference between man and woman worldiwide: 1.6
However ideal BMI is still not very accurate as a measure of how healthy you are as it does not differentiate between muscle mass and fat mass.
This is why we need to look at body fat percentage.
Ideal body fat percentage
Even with all these calculations a proper Calorie Intake Calculation tool would be useless if it did not contemplate what we care most about: body fat percentage.
You can know your body fat with three methods:
· Taking measures of skin folds at different parts of your body (most accurate, but not very precise).
· Using an impedance scale (not very accurate, but more precise)
· Comparing your body shape to standard pictures (not accurate or precise but really easy).
In our Calorie Intake Calculator tool we offer the later method because it’s accessible, but if you have a better measurement please enter it instead.
Knowing your BMI and body fat percentage we can calculate your lean weight and fat weight:
CURRENT FAT WEIGHT = CURRENT WEIGHT * CURRENT BODY FAT PERCENTAGE
CURRENT LEAN WEIGHT = CURRENT WEIGHT – CURRENT FAT WEIGHT
With your ideal BMI and desired body fat we can calculate your ideal fat and lean weight.
IDEAL WEIGHT = IDEAL BMI * HEIGHT2
IDEAL FAT WEIGHT = IDEAL WEIGHT * IDEAL BODY FAT PERCENTAGE
IDEAL LEAN WEIGHT = IDEAL WEIGHT – IDEAL FAT WEIGHT
From here we infer how much fat you need to lose and how much muscle you need to gain.
FAT TO LOSE/GAIN = CURRENT FAT – IDEAL FAT
MUSCLE TO GAIN = MAX(IDEAL LEAN WEIGHT – CURRENT LEAN WEIGHT, 0)
See that the formulas can tell you to gain fat (if you are too thin) but never to lose muscle.
We consider that there is a minimum muscle you need to be healthy but more is good within reasonable levels.
How long it will take to reach your ideal BMI?
Now that we know your ideal BMI, fat to lose and muscle to gain we want to give you an estimation of how long it will take to reach your goals.
If you want to lose weight, you’ll need to create a calorie deficit.
That does not mean starving!
Following a true calorie restriction diet is torture, and we don’t want you to suffer.
It would also create stress for your body, which would react by activating all the mechanisms to recover the lost weight by lowering your metabolic rate.
Your body might even try to increase its reserves!
Our body understands sudden weight loss as a result of an the environment that doesn’t have enough food, so it triggers an “energy saving” program and will try to gain as much fat as possible putting you further from your ideal BMI than before.
We set our caloric deficit to not less than 80% of TDEE.
In case you decide to use Mammoth Hunters App we will organize your daily meal plan with a macronutrient composition to encourage fat burning.
We understand that if you choose to stay healthy you feel good about your body and you consider you are already in your ideal BMI. We thus don’t recommend any weight loss or gain.
Recommended calories will be just TDEE.
This does not mean that you don’t need a body composition restructuring.
If you follow the Mammoth Hunters training and nutrition program (PRO), we’ll adjust the macronutrients you eat to trigger a metabolic transformation.
The proportion of muscle and fat in your body will change gradually to reach its optimal level.
You will also gain or lose weight to reach your ideal weight, but gradually and without any physiological stress.
If you want to gain strength, you need to consume excess energy that consists of protein and carbohydrates to gain muscle.
In this case, we assign 20% more calories to your diet so you can start generating muscle mass that you are looking for.
Remember that this will only work if you do enough exercise. Otherwise this excess will be used to create more fat reserves.
The Mammoth Hunters App offers the right training program to succeed with a muscle gain diet.
Beyond the calorie intake calculation tool
The calorie intake calculation tool has a notable and important limitation.
It takes a static picture of you and only gives you average results without considering the exercise you do day by day.
The Mammoth Hunters App can better predict your calorie intake with daily monitoring.
This allows for a more accurate prediction that includes exercise and the afterburn effect, and that constantly adjusts the level of your exercise intensity to keep your body challenged and improving.
To calculate how much energy you spend doing exercise we use standard metabolic equivalent measurements (METS).
METS = Calories consumed per Kg of bodyweight per unit of time
See below a the table used to calculate calories for some common metabolic exercises below.
|Speed (min/km)||METs (Kcal/min/kg)|
|Speed (min/km)||METs (Kcal/min/kg)|
|Speed (min/km)||METs (Kcal/min/kg)|
|Speed (min/km)||METs (Kcal/min/kg)|
You can find a more exhaustive table of all sports here (link).
Afterburn effect/ EPOC (Excess Post-exercise Oxygen Consumption)
Afterburn effect is caused by an increased metabolism after training.
It’s very important, especially in high intensity sessions.
In fact, scientific literature says that this value is proportional to the intensity of a session. The session length is another factor to consider although it is not as important.
The afterburn effect explains why short, high intensity sessions help burn fat more efficiently than long runs at medium or low intensity  . We wrote more about the subject in this article.
After reviewing the literature, we have defined the afterburn effect for different intensity workouts:
The graph shows the increase in energy consumption after training as a percentage of BMR that decays with time
The values of this equation are:
PERCENTAGE INCREASE in BMR (at Hour n) = Initial EPOC – 0.85% EPOC x n
The Calorie Intake Calculation tool you have in your hands is the best science can offer.
This tool will give you a very good approximation of your ideal BMI and the calorie intake you need to reach it, and exercise you should undertake to support reaching your goal.
Keep in mind its limitations (static picture, no consideration of your macronutrient composition, no consideration of training efforts and afterburn effect).
If you want to get a personalized training and nutrition program check out our App. It’s free to start!
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