BMR Calculation
For males:
BMR=(10 × weight (lbs))+(6.25 × height (in)) − ( 5 × age) + 5
For females:
BMR=(10 × weight (lbs)) + (6.25 × height (in)) − (5 × age) − 161
This calculates your resting calorie burn.

TDEE Calculation:
The BMR is multiplied by an activity level multiplier to get your Total Daily Energy Expenditure (TDEE):
TDEE=BMR × activity multiplier
The activity multiplier is based on your level of physical activity, ranging from sedentary (1.2) to very active (1.9).

Target Calories
Based on your goal:

To lose weight: Target calories = TDEE × 0.85
To gain weight: Target calories = TDEE × 1.15
To maintain weight: Target calories = TDEE
Protein Calculation:
Protein intake is set equal to your weight in pounds (1 gram per pound of body weight):
protein (grams) = weight (lbs)

Fat Calculation:
Fat intake is 25% of your target calories, and since 1 gram of fat equals 9 calories:
fat (grams)=(target calories×0.25) / 9

Carbs Calculation:
After calculating protein and fat calories, the remaining calories go-to carbs. Since 1 gram of carbs equals 4 calories:
carbs (grams)= (target calories−(protein grams × 4 + fat grams × 9)) / 4

The activity multiplier adjusts your BMR (Basal Metabolic Rate) to account for the calories you burn through physical activity. Since BMR only reflects the calories your body needs at rest, the activity multiplier gives a more realistic picture of your total daily energy expenditure (TDEE). Here’s how the multipliers work:

Sedentary (1.2): Little to no exercise, mainly sitting or minimal movement throughout the day. This multiplier adds about 20% more calories to your BMR.
Lightly Active (1.375): Light exercise or activity 1-3 days per week. For example, you are walking or doing light household chores. This adds around 37.5% more calories.
Moderately Active (1.55): Moderate exercise or sports 3-5 days per week, including regular workouts or an active lifestyle, increases your calorie needs by 55%.
Very Active (1.725): Hard exercise or physical activity 6-7 days a week. This might be consistent gym sessions, strenuous sports, or a labor-intensive job. Adds 72.5% more calories.
Super Active (1.9): Very hard exercise, physical labor, or twice-a-day training. This category is for athletes or people with extremely high physical demands, adding 90% or more calories.
The activity multiplier scales your daily calorie needs based on your physical activity.