The formula to calculate the minimum calories per day is:
\[ \text{Calories per day} = BMR \times A - 1000 \]
Where:
Let's say the basal metabolic rate (BMR) is 1500 calories and the activity factor (A) is 1.2. Using the formula:
\[ \text{Calories per day} = 1500 \times 1.2 - 1000 \]
We get:
\[ \text{Calories per day} = 1800 - 1000 = 800\, \text{calories} \]
So, the minimum calories per day is 800 calories.