Weight Loss Science
April 22, 2010 @ 11:33 am
I've been thinking a lot lately about calories and the basic numbers game that makes up weight loss. Essential to a weight loss effort is understanding
Basal Metabolic Rate or Resting Metabolic Rate. In a nutshell, BMR is the number of calories your body needs to burn for basic operations every day (breathing, heart, moving, walking, cellular regeneration, etc). Eat less than your BMR and you start burning your reserve energy ... your fat.
Calculating BMR is a squishy science. It's pretty tough to know exactly how many calories our bodies use, and everyone is different. The BMR for a fat 250-lb guy with 32% will be different than that of a 250-lb guy who's all muscle and 4% body fat. But still, we can get rough estimates using one of three equations.
Harris-Benedict
Harris-Benedict is the oldest equation for calculating BMR, developed in 1919, and is the most widely used. But it's also the least reliable, having the potential to overestimate by at least 5%. The discrepancy was highlighted by Mifflin & St Jeor who came up with the second equation below. But since this is a squishy science, it's better to look at all the equations for a rough estimate of where your BMR actually is.
Mifflin-St Jeor
In the 1990s, Mifflin & St Jeor came up with a new equation for calculating BMR. They found that the Harris-Benedict equation tended to overestimate by up to 5% (more for heavier people), which would mean people could think they have a higher BMR than they do, eat more than they should, and not lose the weight they would expect to lose.
Katch-McArdle
So the first two equations only take into account total body weight, BMI and age. But the reality is that muscle and fat have different energy requirements, so it's important to distinguish between them for the most accurate estimate. Unfortunately, the downside of this equation is that most people don't have a reliable method for calculating their Body Fat percentage, leading to a garbage-in-garbage-out problem with Katch-McArdle. At-home devices are not always accurate, or consistent. Nevertheless, as part of well-rounded view of your BMR, if you have a scale that measures Body Fat %, try this one too.
Handy Tools
So this is a lot of math, and it's in the metric system, which just adds more complexity for those of us in America. For me, I created a
behemoth spreadsheet system in iWork Numbers that calculates all sorts of things and predicts my weight loss journey. But I've simplified that a bit for an easy download that calculates your BMR based on all three equations. I also threw in a "Weight Loss Predictor" that mathematically predicts your weight based on your calorie intake and calories burned*
Download the LWD Basal Metabolic Rate Tool (Excel) * Note the predictor is just an estimate based on mathematical extrapolation. Individual actual results vary from person to person based on a lot of factors, so this tool does not guarantee any particular weight loss at any particular rate.
2 comments | Topics: BMR, science, weight loss tools
Journey Updates
April 13, 2010 @ 10:26 am
A number of the bloggers I follow don't weight themselves with any regularity ... or at all. The idea is that one shouldn't let their lives and weight loss efforts be ruled by a number on a scale; it emphasizes that this journey is about overall health and well being, about how clothes fit, etc. It's totally valid, and I agree with not weighing oneself daily, but I can't avoid the scale entirely.
When I avoid the scale, bad things happen. Humans tend to have a skewed perspective on themselves; we're really good at fooling ourselves that we've not eaten that much, or that we're losing weight when nothing is further from the truth. I'm the king of this - and so I need a frequent reality check to ensure my perceptions are still grounded.
The Game
Whether you use a scale or not, weight loss is a numbers game. Number of calories in, number of calories spent. Spend more than you've eaten and you start tapping your reserves, a.k.a. fat. If you tap 3,500 reserve calories you lose a pound of fat. Then repeat the process 100 times.
The key is knowing your basal metabolic rate (BMR) - this is the number of calories your body needs to fuel its daily operations. For me, it's around 2,200 - 2,300 (all equations are only estimates). That means to maintain my weight, I need to eat that many calories. If I eat less than that, I'll start burning reserve calories, which eventually whittles away at my fat stores.
You would think staying under 2,000+ calories is an easy task, that feels like a lot of food, until you start eating a lot of breads, pastas, and pints of Ben & Jerry's in a single evening. When I think about what I've been eating this week compared to what I must have been eating before, it astounds me. Especially when you consider how much exercise I was getting.
Exercise affects the numbers game by essentially giving you wiggle room. If I eat 1,500 calories a day, that's a deficit of 3,500 a week, or 1 pound. If I also exercise and burn 500 calories a day, that's a deficit of 7,000 for the week - or 2 pounds. The key is
net calories - calories eaten less calories burned. Measure that against BMR and you have your deficit (or God forbid, a surplus).
The Awesomest Weight Loss Spreadsheet Ever
All this is basic weight loss that anyone on this journey comes to understand. But it's been refreshed in my head because it's become painfully clear that unless I focus on the numbers side of weight loss - and track what I'm actually doing - I will fail. So being a business & tech nerd, the obvious tool to turn to is a spreadsheet. I may have gone overboard. Click to see a full version.
This sucker takes my daily calories eaten and daily calories burned and then automatically tracks and predicts what my weight loss will be for the week and for every week thereafter. It also keeps a running calculation of my BMR according to the three major equations, so as I lose weight, my BMR automatically drops appropriately and so does my daily and weekly Net Calories targets. And the neatest part is that if I over eat at the beginning of the week, this tool will
tell me automatically what my new daily caloric target should be for the rest of the week in order to stay on track.
It's pretty nifty if I do say so myself.
To calculate calories during the day I'm using
www.myfitnesspal.com.
Will I be tracking this closely for the rest of my journey? I don't know. But for now I need to be retraining my brain to understand just how much food I should actually be eating in order to lose weight, and that means building a mental association between food and calorie counts, so that I can better gauge how well I'm doing (or not).
14 comments | Topics: BMR, calories, food and eating, science, weight loss tools
Journey Updates
January 26, 2010 @ 01:35 pm
Since starting this journey a few years ago I've heard tell of food-logging. Many swear by the importance of writing down what they eat. I ignored them. First off, there was no easy way to do that. I don't carry a notebook with me everywhere, which means I have to remember later what I ate. That turned out to be kind of hard (a problem in and of itself). What's worse, after writing down what I ate, I had to figure out what that meant in numerical terms. Calories. Weight Watchers Points. Whatever.
I was on Weight Watchers for a while and found good success with it. I think it's a great program. I eventually unsubscribed because I just wasn't using it or being healthy at all. The fact is, I don't want to run to the computer every time I eat, log into a website, look up the points, record it, and stare at it. They didn't really have an iPhone application at the time I was actively using their program (now they do, and it's probably great). So part of the problem is that I have to find a
convenient way to record what I'm eating, and the other part of the problem is
finding the actual health quantities for what I'm eating (i.e. calories).
Right now, I'm focusing on eating healthy. I'm focusing on eating a
good balance of nutrients - protein, carbohydrate, omega-3 and other healthy fats. I actually don't care about calories right now. I just want to eat right. I want to eat whole, natural foods. I'm cutting out as much processed stuff as I can. And that solves the second part of the problem -
if I don't care about calories, I don't need to track them. Enter Twitter, Stage Right.
The easiest way for me to track what I'm eating is Twitter. I have it handy on my computer, I have it handy on my iPhone, and my iPhone is always in my pocket. I created a new Twitter account -
@LWDFoodLog - which I can easily post what I eat right when I eat it. I just whip out my phone, jot it down real quick, put phone away. Voila! Food logging!
For an extra-special level of accountability, I make my food log public. You can follow the Twitter account (though why you would want to, I don't know). I also have a little computer doodad that goes out and grabs that Twitter feed and publishes it right here on my site for all to see. And it's working.
I've been sticking with it for a couple of weeks, and I'm pretty happy with it. I'm happy with my progress. I'm happy to look back over the days and see that I've largely eaten well. Almost no High Fructose Corn Syrup, very little sugar - just healthy, natural, live foods rich in good stuffs. But there are mistakes too, there are times I binge, times I go a little crazy eating anything I can find. And that's the key to food logging - being 100% forthright with everything you eat.
I log everything that goes into my mouth that isn't water (well ...). Occasionally I screw up. I log those too. If I didn't log everything, there would be no integrity to the food log and I might as well log nothing. Because if I can't actually see what I'm eating, I'll never learn. If I don't honestly record what I eat, any doctor or nutritionist I enlist to help me down the road won't have all the facts. And practicing these levels of honesty and integrity with something so simple as food logging teach me to be honest with myself in every area of my health.
1 comment | Topics: food and eating, tips, weight loss tools
