Mifflin – St. Jeor Calorie Calculator

How many calories do I need?

An acceptable macronutrient distribution range for carbohydrates (45-65% of energy), protein (10-35% of energy), and fat (20-35% of energy; limit saturated and trans fats). These recommendations are broad and meant to cover the needs of many different people with different dietary situations. This is a much-discussed and debated issue, and the current understanding is that there is no one-size-fits-all recommendation. How many calories you consume and what percent of your calories come from each macronutrient can be manipulated to meet your individual needs and goals. However, consuming adequate protein at or above the recommended amount is necessary to maintain lean body mass.

About

The Mifflin-St Jeor equation is a widely used tool to determine the resting metabolic rate [RMR], which is defined as the number of calories burned while the body is in complete rest. RMR is also known as resting energy expenditure [REE]. The equation was developed by MD Mifflin and ST St Jeor and first introduced in a paper published in 1990. We are using this calorie calculator at our Bhavishya Clinic+

There are several equations for measuring RMR, including the most popular Harris-Benedict equation which was developed in 1919 and revised for accuracy in 1984. A comparative study of four predictive equations found that the Mifflin-St Jeor equation is more likely than the other equations to predict RMR to within 10% of that measured.

Formula

Females: (10*weight [kg]) + (6.25*height [cm]) – (5*age [years]) – 161
Males: (10*weight [kg]) + (6.25*height [cm]) – (5*age [years]) + 5

Multiply by scale factor for activity level:
Sedentary *1.2
Lightly active *1.375
Moderately active *1.55
Active *1.725
Very active *1.9

Basal metabolic rate is the amount of energy needed for your body’s physiological functions at rest, such as your breathing, your heart beating, and your brain activity.

This amount of energy required is measured in kilocalories, or often just denoted as calories. Therefore, BMR is your body’s calorie needs at rest with no extra activity.

In order to measure your exact BMR, you need to be in a lab setting and use indirect calorimetry. This measurement is taken under tightly controlled conditions and not easily accessible to most people.

Caloric expenditure measured by indirect calorimetry can then be added to physical activity energy expenditure to calculate total daily energy expenditure.

What is resting metabolic rate (RMR)?

Resting metabolic rate is the total number of calories burned when your body is completely at rest. RMR supports breathing, circulating blood, organ functions, and basic neurological functions. It is proportional to lean body mass and decreases approximately 0.01 kcal/min for each 1% increase in body fatness.

Hunger Vs Appetite

Lastly, take the time to understand some basic differences between hunger and appetite which are outlined below:

Hunger

It is considered a biological response to replenish the body’s energy reserves.

• Protects us from starvation.
• Usually triggered by an event occurring below the neckline:
  • Low blood sugar.
  • Empty (growling) stomach.
  • Hormone fluctuations.
  • Need to warm body (hypothermia).
• Gradual onset, appearing after several hours without food and typically diminishes after eating.
• It is generally satisfied by almost any food that provides energy (calories).

Appetite

It is considered a desire or interest to eat a specific food.

• Usually triggered by an event occurring above the neckline consciously or subconsciously:
  • Thoughts, emotions and moods.
  • Social (e.g., happy hour)
  • Cultural (e.g., family)
  • Environmental (e.g., walking into a bakery).
• More rapid onset and often independent of hunger.
• Not time-dependent and may persist after eating.
• Usually only satisfied by a specific food (e.g., sweet, salty) which may then evoke emotions and thoughts afterwards (e.g., pleasure, guilt, shame).

While RMR is an important component of TDEE, an accurate measurement remains elusive for many. Subsequently, we resort to mathematical formulas, but considering their potential errors, the values determined should always be considered a general estimate rather than an accurate value. Given this, there may also be value in including other methods as a guide to avoiding starvation. 

Lastly, while we need to acknowledge the fact that RMR is not entirely controllable, there are some influencing factors we can manipulate and should leverage every opportunity to exploit them.