How Many Calories Should I Consume? Basic Nutrition Course

By Author: INFS(Institute of Nutrition and Fitness Sciences)
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How Many Calories Should I Consume Daily? A Practical Guide for Better

Nutrition and Fitness

You should aim for a daily calorie intake tailored to your body, activity level, and goal (loose, maintain or gain weight), it is not a "magic number". For most healthy adults this usually falls somewhere between about 1,600-3,000 calories per day, with women typically on the lower end depending on the activity. Whether you are looking to learn nutrition online or just starting with a basic nutrition course, understanding your calorie needs is always the first step.

What Are Calories?
A calorie is a unit of energy that your body uses to power everything from breathing and organ function to walking, thinking, and exercise. You gain calories from food and drinks, and you burn them through your basic metabolism plus all physical activity.

What are the factors that Decide Your Calorie Needs
Your daily calorie requirement is influenced mainly by:

Age (usually need fewer calories as you get older).
Sex (on average, men need more than women because of the higher lean mass).
Body size ...
... and composition (taller, heavier, more muscular bodies burn more).
Activity level (sedentary vs very active makes a big difference)
Goals (weight loss, maintenance, muscle gain, pregnancy, etc.)
Average reference values often used in public health are around 2,000 calories per day for women and 2,500 for men in many countries, but these are only broad guidelines, not personalized prescriptions. In India, ICMR reference values for adults suggest roughly 2000 calories per day for a sedentary man and 1690-1800 for a sedentary woman, with higher targets for more active groups.

Step 1: Estimate Your Basal Metabolic Rate (BMR)
Your basal metabolic rate (also called your resting metabolic rate) is the number of calories your body uses at rest for vital functions like breathing, circulation, and maintaining body temperature. A widely recommended way to estimate this is the Mifflin-St Jeor equation, which has been validated in several studies and is considered reasonably accurate for many adults.

For men: BMR= 10 X weight (kg) + 6.25 X height (cm) – 5 X age (years) + 5

For Women: BMR: 10X weight (kg) + 6.25 X height (cm) – 5 X age (years) – 161

Example: woman (30 years, 60 kgs, 160 cm): BMR ? 10 x 60 + 6.25 x 160 – 5 x 30 -162 = 1289 calories/day This is the energy her body would use if she were at complete rest all day.

Step 2: Adjust for Activity to Get Your TDEE
Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor to account for movement, exercise, and daily chores. Typical activity multipliers are:

Sedentary (mostly sitting, little exercise): multiply BMR by about 1.2.
Lightly active (light exercise 1-3 days/ week): multiply by about 1.375.
Moderately active (exercise 3-5 days/ week): multiply by about 1.55.
Very active (hard exercise 6-7 days/week): multiply by about 1.725.
Extra active (very hard exercise or physical job): multiply by about 1.9
Continuing the example- lightly BMR ? 1,289 TDEE ? 1,289 X 1.375 ? 1,770 calories/ day to maintain her current weight if she is lightly active.

Example: moderately active man (30 years, 75 kg, 175 cm): BMR ? 10 x 75 + 6.25 x 175 – 5 x 30 + 5 ? 1,718 calories/ day. TDEE ? 1,718 x 1.55 ? 2,660 calories/day to maintain his weight with moderate activity.

Step 3: Adjust for Your Goal
Once you know your TDEE, you can set a calorie target based on what you want to achieve.

To maintain weight: Aim close to your TDEE (e.g., if TDEE ? 2,000, eat around 2,000 on average).
To lose weight safely: Create a deficit of about 300-500 calories per day below TDEE for slow sustainable loss (roughly 0.25 – 0.5 kg per week for many people).
Very low intakes (e.g., under 1,200 for most women or 1,500 for most men) generally should only be used under medical supervision.
To gain weight or build muscle: Add about 250-500 calories above TDEE and combine this with resistance training to promote lean mass gain instead of only fat.
How to Apply Calorie Counting in Daily Life
To make "How much should I eat?" practical:

Calculate your BMR and TDEE using Mifflin-St Jeor equation and an activity factor.
Set a clear goal (lose, maintain, or gain) and adjust your calories by about 300-500 up or down from your TDEE.
Track for 1-2 weeks using a food diary or app and compare your actual intake to your target.
Monitor your body: if your weight and energy are changing in the desired direction, you are probably close to your requirement; if not adjust by 100-200 calories and reassess over another couple of weeks.
This approach turns daily calorie consumption into a flexible, data-driven habit rather than a rigid rule, helping you find the intake that truly works for your body and lifestyle. If you want to build this knowledge more systematically, the INFS nutrition course and other structured fitness and nutrition courses are a great place to start , covering everything from BMR and TDEE to advanced diet planning.