Calories are so much fun… said no one ever. They are necessary for life but yet add to that muffin top baking over the side of your jeans. They are in everything but can make you feel completely different depending on where they come from. And best of all, we need a different amount of the little buggers to function properly without gaining weight or losing weight. So what really is a calorie and how many of the little creatures do we really need?
A calorie is simply a unit of energy, that’s it that’s all it is. It is literally the amount of energy it requires to raise the temperature of one gram of water one degree Celsius. Or in terms of food, a Calorie (which is actually a kilocalorie but referred to as a Calorie) is the amount of energy required to raise the temperature of one kilogram of water one degree Celsius. In other words a nutritional Calorie is actually one thousand calories. Yay science!
All of that science mumbo jumbo is great but how the hell does raising the temperature of a kilogram of water have to do with your waistline? Good question. The best way to think about this is to imagine the human body as a car. A car has the ability to store energy in the form of a gas tank; plus one gallon of gas contains 31,000 nutritional Calories so it really is pretty similar to the body. So just like the car, our bodies have the ability to store energy. This is a good thing otherwise we would die pretty fast without the ability to store energy. But instead of just a gas tank, the body stores energy in the form of fat and glycogen. But just for our purposes we will just refer to the body’s “gas tank” as the fat.
When we consume food, we are consuming and extracting the energy that comes from that food. That energy that is contained in the food is the Calories that the food contains. It’s like we are filling up our bodies own gas tank. Thankfully evolution has given us the ability to store these Calories that we have consumed in the form of fat. Good for survival, but bad for our waistlines. The more energy we consume (ie. Food) the more fat we create to store the extra calories. This is an amazing evolutionary skill that allowed us to stay alive in times of food scarcity, but now that we get our food from a shelf rather than running after it with a spear, the ability to store fat is more of a side show trick to help us become obese. I mean I guess if the apocalypse ever hits, the fattest will be the ones to last the longest without food, but they will also be the easiest prey for the zombies.
With all of that said, how many calories do we actually need? Again, good question. This is really going to depend on a few factors, height, weight, age, gender, muscle, fat, daily activity, workouts, lifestyle, diet, thyroid, adrenals, androgen hormones, and sleep just to name a few. This is why it varies so much from person to person. A 6 foot tall 200lb dude that works out every day and works in a factory may need somewhere in the range of 3,500 calories per day just to maintain his weight. Or another 6 foot tall 200 pound man that works a desk job and only works out once in a blue moon will most likely be just fine with 2,000 calories. Or for the female side, a 5 foot 6 135lb athletic female that exercises daily, has two kids, tends to a garden, and works as waitress would need up to 2,500 a day just to maintain her weight; whereas a 5 foot 6 130lb female that works at a desk all day and watches movies as a hobby would only need like 1600 calories a day. So as you can see estimating calorie intakes can be very tricky if you just pick a number that you think is right.
Luckily there are ways to somewhat get a ballpark range for what you should be consuming. The first thing to consider is age. How old are you? The older you are the less calories you are going to need, it’s sad but it’s true. Gone are the days of getting away with eating anything in sight as you get older. This also has to do with the hormones, your androgen hormones naturally drop as you get older which also means that your body will tend to expend less energy. So the older you are the fewer calories you will need and the younger you are, the more Calories you will need, especially if you are still growing.
The next thing to consider is gender. Sorry ladies, it really sucks but it is just a fact that females require fewer Calories than males. I wish there was a way around it, but Mother Nature decided that males require more energy so us lucky bastards with a pair of dangleies between our legs can get away with a bit more food. This also has to do with the hormones as well. The extra testosterone a male generates ads to the muscle mass in males, which burns more calories. Every time I work with a female that wants to lose weight, it sucks having to tell them that they don’t burn as many Calories as their male counterparts, but it’s just a fact of life. On the flipside ladies, rest assure that you would last much longer in a famine than a male would. This is why on the survivor TV shows the males always lose about 45lbs in a month and the females only drop around 20lbs.
After the gender comes lifestyle. This is going to play a HUGE role in the amount of calories you need per day. By lifestyle, I am referring to two separate things; physical activity and work. Physical activity is the amount that you move your body in a day. This includes exercise, mowing the lawn, gardening, walking the dog and anything that gets you moving. All of that requires energy that comes from your body’s “gas tank” (Fat). It can be argued that some of this energy comes from glycogen and ATP phosphate but for the sake of simplicity, all of it is going to come from fat in this case. The more you move the more you burn. The other part of activity is work, this is how much moving around and activity you do at work. If you are a UPS or FedEx package deliverer you will require way more calories than a computer programmer that sits at a desk all day. Sitting at a desk requires immense brain power, but you aren’t building up any kind of sweat typing on a keyboard. There are things that can change that up a bit like a standing workstation and other energy requiring devices like that but that is a whole separate post in itself. The more you move the more you burn and the more Calories you are going to need, the less you move the less you need. A sloth needs a lot less calories than a horse.
Another thing to consider when figuring out how many Calories you need per day is your hormones. You have TONS of hormones and all of them can affect how much energy your body puts out on a given day. Thyroid is going to be a major player in this game so that will be the main one to focus on for energy output. The thyroid gland located in your neck produce a few very power full hormones known as T3 and T4 (triiodothyronine and thyroxine respectively). It also produces calcitonin, but that plays a role in the body’s calcium levels. These hormones that your thyroid produces control the amount of energy that the body expends; it controls protein synthesis, and even controls how sensitive you are to the other hormones produced in your body. This is why the thyroid is so important in the amount of energy that you expend each day. The more active that your thyroid glands are, the more energy you will expend and the more Calories you will need on a given day. On the flipside, if your thyroid glands are not functioning properly and are less active than they should be, your body will expend a lot less energy require fewer calories. The best way to test your thyroid is to go get a blood test, which will tell you where your levels are at so you know for sure. Don’t just try to guess how active your thyroid is unless you are extremely cold all of the time, have immense fatigue that is crippling and have absolutely no sex drive whatsoever. Then your thyroid glands may be sluggish, but still get them checked.
So as you can see, estimating the amount of Calories that you need can be extremely tricky. Between your age, height, weight, muscle mass, activity level, job, and hormone levels there are tons of different factors that all play into the amount that you need in a given day. You’ll need more if your extremely active, young, have a lot of muscle and work a job that requires physical labor; and you’ll need less if you are older, sedentary, and work a desk job. It would be nice to be able to give exact numbers but everyone is completely different. If you want me to give you the number of Calories that you specifically need for your body then send me an email with you height, weight, age, gender, work, and activity level. I can send you how many that you need in a day to maintain, lose, or gain weight depending on your goals. Otherwise if you know how many you need for your basal metabolic rate (the amount to just survive) then you can adjust for your own body based on the info above. Calories are a fun game of numbers but they are really just a unit of energy and can be quite fun when you know just how many you need to function at your body’s prime.