What should be my daily calorie need?

Bowl of nuts, fruits and other nutritious foods

A calorie is the unit of measurement for energy. You need calories in your daily life to perform different tasks. Even when you are not doing anything and sleeping you need calories to maintain internal body functions. When you are doing physical activities, your calorie need also increases.

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What is energy? 

Energy is needed for our bodies to function. It is the capacity to perform work. There are many forms of energy;

  • Heat energy
  • Mechanical energy
  • Chemical energy
  • Electrical energy

Energy can be stored, released, moved, or transformed from one form of energy to another.  We get our energy mainly from the food we eat. carbohydrates and fats are the main sources of energy that we get from food. Following is a list showing how much energy is provided by 1 gram of each nutrient. 

  • the carbohydrate in food provides 4kcal.
  • protein in food provides 4kcal
  • fat in food provides 7kcal
  • the alcohol we consume provided 7kcal

When the amount of energy we spent equals the amount of energy we consume from food, we can maintain our body weight. But when we consume excess energy through food, our body stores energy as fat and we become obese or overweight. You can use a calorie calculator to calculate the number of calories you need.

How much energy do we spend?

The following activities use energy in our body ;

  1. Basal and resting metabolism
  2. Physical activity
  3. Thermic effect of food
  4. Non Exercise activity thermogenesis (NEAT)

Our body spends about 60% -70% of the energy on metabolism, 15% – 30% on physical activity, and 10% on heat production in the body.

What is Basal Metabolic Rate (BMR)?

We need the energy to maintain basic psychological functions in our body. That is why we need energy when we are at rest and after 12 hours of fasting. BMR is the amount of energy we spend after 12 hours of fasting and at rest

About 2/3 of energy expenditure is for BMR. BMR is measured after 12 hours fast while the person is resting physically and mentally, and maintain in a thermoneutral, quiet environment.

What is the Resting Metabolic Rate (RMR)?

RMR is greater than BMR. We measure RMR in a non-fating state.

Thermic effect of meal

When we eat a meal it takes about 10% of calorie content to digest, metabolize, convert, and store ingested macronutrients.

Other energy expenditure

  • Growth
  • Adaptive thermogenesis- exposure to reduced temperature, fever, and other pathological conditions.
  • The thermogenic effect of foods ad beverages, (Eg: Nicotine, caffeine, capsaicin)

How many calories do we spend when doing physical activities? 

The energy needed for physical activities is greater than the basal energy need. Calories needed for physical activities depend on;

  • The type of activity
  • Duration
  • Intensity
  • Weight of the person

The amount of energy the body needs per day varies from person to person. It varies depending on the person’s weight, age, gender, height, fat mass, fat-free mass, genetic, thyroid function, and amount of physical activity. Several other factors contribute to this. These include muscle mass, body fat, fasting, body growth rate, genetic, hormonal, and neural activity, ambient temperature, infections or diseases, medications, and nutritional deficiencies.

 Energy is expressed in calories. If you want to lose weight, you need to get less energy than your body expends every day. 


Dilini Tharaka

Dilini Tharaka

BSc. (sp.) in Food Science and Nutrition, Specializing in Applied Nutrition (Founder, Editor, and an Author)
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Your well being affects your quality of life. If your body is healthy you’ll also feel good. Proper nutrition can help you to be healthier. 

Dilini Tharaka

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