Your Basal Metabolic Rate is: 1342 Calories. You did not mention your level of weekly activities so I assume you like to hit the gym twice a week for about 1 hour.
This means your daily energy expediture is: 1845 calories, so if you eat 1845 calories a day you should be able to maintain your weight!
In addition I highly suggest you consume 38g of protein (recommend: 0.8g of protein/kg of body weight) to maintain a good body composition. If you are curious on how I calculated your daily energy expenditure please read on below, I highly recommended it.
Calculations: Extra Stuff Below
It’s pretty simple math to figure out how much to eat to maintain a constant weight if you know your stuff. You obviously know that “Energy In” needs to match “Energy Out” to maintain your weight. The hard part is figuring out what is your Energy Out, that’s where I come in to help.
Energy Out depends on three things:
1) Basal Metabolic Rate – Is how much energy your body expends for regular daily functions.
2) Physical Activity – Is how much energy you spend doing your daily chores such as walking, exercising and even thinking (when you do homework seeing you are a student).
3) Dietary Induced Thermogenesis (DIT) – This is the energy you spend when you digest the food you eat. This is the most insignificant amount of energy expenditure and you don’t need to worry about it. But for you interest research has found that protein causes the highest effect of DIT.
Now let’s consider your:
1) Basal Metabolic Rate (BMR): based on your information provided: Female; 105 lbs; 5’8”, 19 years old. Your approximate BMR is about: 1342 Calories.
*You can use a simple BMR calculator online: http://www.bmi-calculator.net/bmr-calculator/
2) Physical Activity: You did not specify how active you are but you can estimate your total daily calorie needs by using the “Harris Benedict Formula”
You can multiply your Basal Metabolic Rate with the activity factor that matches your lifestyle:
- If you are sedentary (little or no exercise) : BMR x 1.2
- If you are lightly active (light exercise/sports 1-3 days/week) : BMR x 1.375
- If you are moderately active (moderate exercise/sports 3-5 days/week) : BMR x 1.55
- If you are very active (hard exercise/sports 6-7 days a week) : BMR x 1.725
- If you are extra active (very hard exercise/sports & physical job) : BMR x 1.9
Putting it all together:
I already told you your BMR: 1342 Calories, if we assume you are lightly active (you hit the gym twice a week for an hour). Your approximate daily energy expenditure will be about: 1342 x 1.375 = 1845
So that means if you eat 1845 Calories each day you will maintain a constant weight of ~105lbs!
Now I do feel compelled to inform you that eating 1845 Calories a day will help maintain your body weight but it won’t maintain your “body composition”. To ensure you maintain a good body composition, try to get 20?f your total calories from protein, 30?rom fat, and 50?rom carbohydrates.
Getting enough protein is the most important in body composition! MAKE SURE you consume at least 38g of protein (recommend: 0.8g of protein/kg of body weight).
Also I know I’m rambling now, and I am in no place to tell you to gain weight but JUST for your interest your Body Mass Index (BMI) is 16, which is underweight. The lowest recommended weight for your height, age, and gender is 120 lbs.
*You can use the BMI calculator here: http://www.exrx.net/Calculators/BMI.html