On the bottom of every nutritional facts label there is a foot note. The footnote tells us that diets based on 2000 & 2500 Calories should have "x" amount of Total Fat, Saturated Fat, Cholesterol, Sodium, Total Carbohydrates and Fiber respectively. That's great, but how do you know which one you should abide by?
How many Calories do you need in a day?
Three things influence how many calories you need in order to maintain your weight.
- Your Metabolism (aka: Basal Metabolic Rate – BMR)
- The amount of activity that you get on a daily basis (aka: Thermic Effect of Activity – TEA)
- How many Calories your body uses to process the foods that you eat (aka: Thermic Effect of Food – TEF)
Your metabolism is responsible for using the bulk of your calories in a day – roughly 75%. A few things contribute to your metabolism:
- Genetics
- Age
- Weight
- Lean Mass
Starting with Genetics, We all know people who can eat all day and not gain a pound; then we
also know people who can just look at a piece of cake & gain a
pound. How efficient we are at using our calories is determined by our parents.
On the bad side, our metabolisms start slowing down after the age of 30 – but some of that has to do with loss of lean mass due to the fact that we aren't as active as we were when we were younger (think about running around outside as kids, or dancing until the wee hours of the morning as teens and young adults).
Weight is also a major contributor to how many calories we burn on a daily basis; but here's where it gets interesting, and here's where we have a bit of control over our metabolisms.
What's more important than weight, is body composition. Weight is divided into two distinct types of tissue: fat, and lean mass. Lean Mass is comprised of your bones, organs, and muscle. Muscle is "metabolically active tissue"; meaning that muscle consumes calories. Fat doesn't consume any additional calories other than that of your body having to work harder to carry additional pounds around on a daily basis – kinda like your body having to lug around a few extra 5# dumbbells.
1 lb of fat will consume an additional 5 Calories per day where 1 lb of muscle will consume an additional 45 Calories. So the lesson learned here is to strength train. Build more muscle and your muscle will help you stay lean.
But how do you know? How do I know how much muscle I have?
First, get your body composition checked. Estimates for BMR is 10 Calories per lb of lean mass. For example; a person with 125 lbs of lean mass would have a basal metabolic rate of roughly 1250. Depending on your daily activity, there are formulas to calculate your TEA – the additional calories that you use in a day.
So, how do I know if I have a slow or fast metabolism?
There's this cool device that will measure the amount of oxygen that your body consumes at rest. It's called a BodyGem by Microlife USA. It's pretty accurate & allows you to see exactly how many calories your body uses at rest. It's a simple test given first thing in the morning after not eating for 12 hours (water is okay, but anything with caffeine or calories is not) or exercising for 24. With a nose plug on (ensuring that all breathing happens through your mouth), you breathe into a device for about 10 minutes. It immediately gives out a reading for your BMR.
To find someone in your area to perform this test click here.