Thursday, March 17, 2011
There are a couple ways to measure how many calories you burn every day. The first way to do this is by counting how many calories you consume over the course of a week, then dividing that amount by 7. For example, If I ate 20,000 calories last week, I can divide that number by 7 to estimate my average daily energy expenditure of 2857 calories:
20,000 kcal (weekly calorie intake) ÷ 7 (days in a week) = 2857 kcal daily
Of course, this only works if your weight isn't changing. It also takes a lot of discipline to write down everything (and I mean everything) you eat on a daily basis. However, there is an easier way.
To get a more immediate estimation, it is possible to estimate your average daily energy expenditure by making a few calculations based on your age, gender, weight, and activity level. First, you have to calculate you're resting energy expenditure. This is the amount of calories that you burn every day from bodily functions not related to physical activity, like breathing, food metabolism, and keeping your blood pumping. In order to do that, use one of the following six formulas:
Male, 18-30 years - (15.3*weight in kg) + 679
Male, 30-60 years - (11.6*weight in kg) + 879
Male, >60 years - (13.5*weight in kg) + 487
Female, 18-30 years - (14.7*weight in kg) + 496
Female, 30-60 years - (8.7*weight in kg) + 829
Female, >60 years - (10.5*weight in kg) + 596
(adapted from National Research Council 1989)
After you've estimated you're resting energy expenditure, you need to use an activity multiplier to account for you're activity level:
very light (almost completely sedentary) - 1.3*REE
light - 1.5 - 1.6*REE
moderate (average active person) - 1.6 - 1.7*REE
heavy - 1.9 - 2.1*REE
exceptional (lumberjack, roughneck on an oilrig) - 2.2-2.4*REE
(adapted from National Research Council 1989)
So lets give this a shot. I'm a 25 year old male and I weigh 168 lbs. there are 2.2 lbs in a kg, so 168/2.2=72.37 kg. Next, I have to calculate my resting energy expenditure:
(15.3*72.37) + 679 = 1786 kcal
Now that I have my REE, I have to use one of the activity multipliers to account for my activity level. Right now I'm a student, so I don't get too much physical activity when I'm not exercising (I account for exercise separately). Since I have a light activity level, I'll multiply my REE by 1.6:
1.6*1786 = 2858 kcal
This is my estimated average daily energy expenditure. It's the amount of calories that I'd have to consume every day if I wanted to maintain my current weight. If I wanted to gain weight, I'd have to eat more, and if I wanted to lose weight, I'd have to eat less. These formulas only give a rough estimate of average daily energy expenditure, so it might take a few weeks to hone in on a more accurate estimation.
Lets say I wanted to lose 8 pounds in 8 weeks. How many calories do I need to consume every day? One pound equals 3500 calories, so if I wanted to lose one pound every week, I'd have to create a 3500 calorie deficit ever week. That means I'd have to create a deficit of 500 calories every day.
2858 (estimated daily expenditure) - 500 = 2358 kcal needed to lose approximately one pound every week.
If I wanted to gain weight, I'd just do the opposite by adding 500 calories.
Counting calories works, but just trust me when I say that it is really really hard. If you ask me, counting calories is no way to live. It will help you in the short term, but the only thing that will keep the weight off is to make a few simple lifestyle changes. Just one little change can make a huge difference in your weight, and more importantly your health. For example, you could cut pop out of your diet or start biking to work instead of driving.
Another thing to keep in mind is that not all calories are created equal. Calories come in three different forms: carbohydrates, proteins, and fats. I'd like to take a break from nutrition for a while, but in a couple weeks I'd like to break down the subjects of carbohydrates, proteins, and fats individually. I've been thinking about how and when I'm going to post blogs. I'll try to post a new blog every Saturday morning. Stay tuned!!
Monday, March 14, 2011
Physical fitness is the foundation for a healthy and happy lifestyle. There are several reasons to become more physically fit. Exercise, sleep, and proper nutrition are all effective in fighting depression. Some research even shows that exercise can be just as effective as medication in cases of clinical depression. People who are physically fit usually look better and feel more confident than people who are not fit. Physical fitness is also positively linked to academic performance. Last but not least, fit people have more fun!!
Think of fitness as a stool with three legs - nutrition, exercise, and sleep. If one of these legs is weak, it could cause the whole stool to crash to the ground... with you on it!!! For example, a lack of sleep can cause you to be more hungry by playing games with your hormones, specifically leptin and ghrelin. Sleep is also the time when your body heals itself after exercise. That's why athletes like professional cyclists get as much sleep as possible.
So what's the most important? Nutrition, exercise, or sleep? Well, according to the three legged stool principal, it depends! It depends because they are all relative to one another. The trick is knowing your weaknesses. Working on your weaknesses will help you with your strengths.
In this blog, I'd like to help people to recognize their strengths and weaknesses in order to become more physically fit. In next week's post, I'll give a brief 101 on how to lose (or gain) weight the right way.
WebMD: Exercise and Depression
Healingwell.com: Depression and Nutrition
Sleepfoundation.org: Depression and Sleep
WebMD: How Sleep Affects Your Weight
Does Physical Activity Influence Academic Performance?