Let’s look at a quick primer about how body weight and calories works. This information can be hard to understand, but as a parent, it’s important you do understand how calories and weight work in order to understand why portion sizes, food types and exercise are also important. Really, this is also important information for you and the adults you care about, not just your kids.
What’s a calorie?
In technical terms, a calorie is the energy it takes to raise the temperature of 1 gram of water 1 degree Celsius. However, that’s not very helpful is it? For purposes related to exercise and healthy eating, calories can simply be considered energy. Everything you or your child does requires energy. Calories in food equal energy that allow you to function.
A calorie is a calorie is a calorie
3,500 calories equal one pound of body weight. There are about 125 calories in a typical bowl of non-sugary cereal. There are about 271 calories in one small serving of fast food french fries. If you eat 3,500 calories worth of either (28 bowls of cereal or 12 containers of fries) that’s one pound. Beyond some very rare foods, most food calories don’t discriminate between ‘healthy’ or ‘not healthy’ foods or calories. If you eat excess calories, no matter the food type, those calories equal excess pounds.
How body weight works
Weight, while admittedly a complex issue, can actually be summed up pretty easily so far as scientific research goes. The CDC, among others, notes that obesity or excess weight ONLY normally occurs because a child eats more calories than he or she uses – meaning, your child eats a lot, but doesn’t offset the food intake with exercise.
Calories in, calories out is how weight happens (or doesn’t happen).
To simple this up, we all have a resting calorie requirement (often called basal metabolic rate, or BMR) that varies by person.
Let’s use a 110 pound, 5 foot, 12 year old girl as an example. Calculators for BMR vary but in general, a teen girl who is 5 feet tall and weighs 110 pounds needs about 1,194-1,359 calories per day to support basic body function like breathing and digestion, before any activities take place. Meaning, if your 12 year old is just laying in bed all day long, not moving, she’s still burning those 1,194-1,359 calories each day because although she’s not active, she is still breathing and her body is burning calories while managing its systems.
What happens to excess calories?
Excess calories are calories your body doesn’t need to survive or in other words, calories you don’t need to maintain your current weight. Any calories you take in above and beyond the basics you actually need to survive, are excess calories and those calories in turn become excess body fat.
BMR is not totally cut and dry though. Your metabolism, gender, age and even your body weight all play a part in how many calories you need to sustain your current weight, not to mention other variables. That said, if you eat too many calories over your BMR and fail to offset those calories with exercise, it’s almost a sure bet that you will, at some point, gain excess weight.
As an example, the Nemours Foundation says that most school-age kids need 1,600 to 2,500 calories per day to maintain and survive. If your child needs 2000 calories but eats 3000 calories a day, that’s 21,000 excess calories per week or 6 extra pounds.
Adding activity to your BMR
When considering calories, you can’t just think about food. You also need to consider calories burned. The most common equation used to calculate necessary calories for an individual is the Harris Benedict equation (HBE). The HBE works as follows…
- If you are sedentary (little or no exercise) : calculate your BMR x 1.2
- If you are lightly active (light exercise 1-3 days/week) calculate your BMR x 1.375
- If you are moderately active (moderate exercise 3-5 days/week) calculate your BMR x 1.55
- If you are very active (hard exercise 6-7 days a week) calculate your BMR x 1.725
- If you are extra active (very hard exercise/sports & physical job or 2x training) calculate your BMR x 1.9
So if your child needs 2000 calories to maintain her weight, but she also exercises moderately, she’ll need to take in 3,100 calories per day to maintain her weight. If she eats more she’ll gain weight, in spite of the exercise and if she eats less, she’ll lose weight. The key is balance – your child should be taking in and burning calories in a balanced manner.
Keep in mind, that the HBE is considered fairly accurate in normally nourished individuals, however, this calculation has been shown to be unreliable in malnourished folks.
To see how many calories typical activities burn, visit Health Status. It’s not perfect, because remember, your body type does dictate calories burned, (for example if weigh 200 pounds and you run for an hour, you’ll usually burn more calories than a 150 pound person who runs for that same hour) but it’s one of the better calculators out there.
Accuracy is a problem
As noted above, weight isn’t something that can be easily regulated to a large group of people. Most BMR and other calorie counters you’ll find online are only semi-useful. Most of these calculators are designed for an average person, when in reality, there’s no such thing. While these calculators can be useful general tools. The best way to find out how many calories your child should be eating per day is to speak with your child’s pediatrician.
If you do want to try a calorie calculator, stick to health minded websites like:
- The Mayo Clinic Calorie Counter
- CDC BMI calculators for kids and adults
- Baylor College of Medicine healthy eating calculator for kids or adult calorie needs
If you’re looking for a way to track calories in common food items, check out the following:
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