The number of calories a person needs can vary significantly based on several factors, including age, height, activity level, and overall health. To give you a generalized estimate for a 137-pound girl, we can use the Mifflin-St Jeor equation, which is a commonly used method to calculate basal metabolic rate (BMR) and total daily energy expenditure (TDEE).
Step 1: Calculate BMR
For women, the Mifflin-St Jeor equation is:
\[ \text{BMR} = 10 \times \text{weight (kg)} + 6.25 \times \text{height (cm)} - 5 \times \text{age (years)} - 161 \]
Step 2: Convert weight to kg
137 pounds is approximately 62.1 kg.
Step 3: Estimate TDEE
Multiply the BMR by an activity factor to estimate total daily energy expenditure:
- Sedentary (little or no exercise): BMR × 1.2
- Lightly active (light exercise/sports 1-3 days a week): BMR × 1.375
- Moderately active (moderate exercise/sports 3-5 days a week): BMR × 1.55
- Very active (hard exercise/sports 6-7 days a week): BMR × 1.725
- Super active (very hard exercise, physical job, or training twice a day): BMR × 1.9
Example Calculation
Let's say the girl is 20 years old and 5'4" (163 cm) tall, and she is moderately active.
- Convert height to cm: 5'4" is about 163 cm.
- Calculate BMR:
\[ \text{BMR} = (10 \times 62.1) + (6.25 \times 163) - (5 \times 20) - 161 \] \[ \text{BMR} \approx 621 + 1018.75 - 100 - 161 \approx 1378.75 \text{ calories/day} \]
- For a moderately active lifestyle:
\[ \text{TDEE} = 1378.75 \times 1.55 \approx 2137.06 \text{ calories/day} \]
Conclusion
In this example, a 137-pound girl who is 20 years old, 5'4" tall, and moderately active would need approximately 2137 calories per day to maintain her weight. If she wants to lose weight, she might aim for a calorie deficit, and if she wants to gain weight, she would seek a caloric surplus.
Always consider consulting with a healthcare professional or a registered dietitian for personalized advice.