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  1. #51
    Senior Member tony_merlino's Avatar
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    There is nothing magical about this. Each of us is an individual, and our bodies transform food to energy with different efficiencies based on genetics, activity level, hormonal/endocrine changes, etc. We don't need to know the internals. You can treat the body as a black box, the internals of which are unknowable. However, you can measure certain characteristics: Input, in terms of how many calories you take in. State, in terms of measuring your weight accurately and frequently (daily). And, with less precision, a rough guess as to the amount of exercise. The last isn't even strictly necessary.

    If you track your calories and weight for a month, keeping your activity level fairly consistent during that time, you can develop a sense for your own body's "transfer function". Once you know that, you're good to apply control to the process. It's true that the black box isn't time invarying, but over a reasonable observation interval, it's close enough. You can recalibrate this process as you go along.

    Your body can't get or store energy from food it doesn't take in. If you're not losing, you need to either reduce the amount you're eating (no matter how uncomfortable that is), or increase your activity - without increasing the amount of food you eat to sustain it. Or both. There is no other way.
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  2. #52
    attacking the streets!
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    Quote Originally Posted by goldfinch View Post
    I remembered this thread today when I was reading an article about a study that looked at metabolic differences between people who had lost weight and were maintaining for at least a year and those that did not lose weight. The researchers were working on puzzling out some of the reasons so many people regain weight.

    They discovered that there is in fact a decrease in metabolism, resulting in about a 150 calorie a day difference. But the real big difference is that people are less active and thus burn less calories. They become too efficient:

    This doesn’t mean we exercise less, either, as exercise is a conscious choice. It means we unconsciously reduce our NEAT [non-exercise activity thermogenesis] and spontaneous activity. It also means we become more efficient in the activity we do; we expend less calories for the same movement. In fact, 35% of the decrease in activity energy expenditure can be attributed to an increase in efficiency. Overall, we move around less, and we become more efficient at the movements we perform. Combined with a decrease in resting metabolic rate, we end up burning over 400 calories per day less than you would expect for someone of our same height, weight, gender, and body composition. This is not only why weight loss eventually plateaus, but also why weight is so easily regained.



    The solution is activity. Maybe, as Jethro suggest, to adopt a somewhat inefficient lifestyle.

    The article goes on to state:

    Remember that physical activity doesn’t have to include formal exercise. NEAT makes up the majority of your activity energy expenditure, and thus has the greatest ability to impact it. In fact, walking at only 1 mile per hour will double your energy expenditure over sitting. Thus, anything that you can do to accumulate physical activity throughout the day will dramatically improve your chances of maintaining weight loss over the long haul. Even small things, like parking a car further away from a destination, or taking stairs rather than an elevator, can add up if accumulated throughout the day. But because activity can decrease on an almost unconscious level, you need to make a deliberate conscious effort to get as much activity as possible in throughout your day, every day


    http://weightology.net/weightologyweekly/?page_id=415
    that's really interesting.

    since i started losing weight, i have been increasing my level of movement throughout the day, i figured i'd treat exercise like snacking. so far it has been working for me.

    i also vary my exercises regularly, both in weight lifting and cardo.

  3. #53
    Climbers Apprentice vesteroid's Avatar
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    I don't know what it is that makes us all different but we are. I have a buddy who I have known since we were 14. This guy can eat and drink anything, anytime, and never gain an ounce. Has the body of a Greek god. Me on the other hand, I look at a French fry and gain weight.

    I don't know what you call it, low metabolism or whatever but it exist in my opinion.

  4. #54
    Senior Member bassjones's Avatar
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    There are some medical conditions that can cause a person's metabolism to be very slow. Low testosterone in men, hypothyroid in both men and women (though more common in women) are two fairly common such conditions. Low T is particularly troublesome because it contributes heavily to weight gain, and the weight gain then lowers the testosterone even more, creating a nasty cyclical effect.
    Last edited by bassjones; 04-30-12 at 04:57 PM.

  5. #55
    attacking the streets!
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    Quote Originally Posted by bassjones View Post
    There are some medical conditions that can cause a person's metabolism to be very slow. Low testosterone in men, hypothyroid in both men and women (though more common in women) are two fairly common such conditions. Low T is particularly troublesome because it contributes heavily to weight gain, and the weight gain then lowers the testosterone even more, creating a nasty cyclical effect.
    there are legitimate medical situations that can put a person at a disadvantage to losing weight, but i'm willing to bet this is not the case for most overweight people. being lazy, inactive, eating junk food and/or over eating is.

  6. #56
    Senior Member goldfinch's Avatar
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    People overeat due to a complex mix of reasons, including physcial, psychological (which overlap) and enviromental. Calling overweight people lazy is a moral judgment, and circular--people are fat, they must be lazy. Losing weight and keeping it off does take significant motivation but motivation may not be enough given that the majority gain their weight back over time. I will never call an overweight person lazy. I do not walk in their shoes.

    Going back to my post about metabolic changes after losing weight, it is helpful to know things to watch out for once you lose weight and one is the possibility that you actually may be conserving energy by being less active in your non-exercise times. I am trying to be aware of that and be a bit less efficient in my day to day activity outside of exercise.

  7. #57
    rugged individualist wphamilton's Avatar
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    I think "efficiency" may be a misnomer here, the other side of the coin from "lazy". The peripatetic person is sometimes more active simply because he sets more tasks for himself, rather than performing them with an inefficient excess of movement.

  8. #58
    Senior Member goldfinch's Avatar
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    Quote Originally Posted by wphamilton View Post
    I think "efficiency" may be a misnomer here, the other side of the coin from "lazy". The peripatetic person is sometimes more active simply because he sets more tasks for himself, rather than performing them with an inefficient excess of movement.
    Not really. There are three things going on. One, your metabolic rate actually is lower. But that isn't a huge number. Two, you become less active outside of exercise. Three, you become more efficient in the activity you do. From the article:

    It means we unconsciously reduce our NEAT and spontaneous activity. It also means we become more efficient in the activity we do; we expend less calories for the same movement. In fact, 35% of the decrease in activity energy expenditure can be attributed to an increase in efficiency. Overall, we move around less, and we become more efficient at the movements we perform. Combined with a decrease in resting metabolic rate, we end up burning over 400 calories per day less than you would expect for someone of our same height, weight, gender, and body composition. This is not only why weight loss eventually plateaus, but also why weight is so easily regained.

  9. #59
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by Chaco View Post
    It always amusing to me how people can look at car engines and realize that the way car engines "metabolize" gasoline is not a simple equation. The mileage you get depends on the age of the car, the timing of the valves, the octane content of the gasoline, and dozens of other factors.

    Yet when it comes to the human body, which is thousands of times more complex than a car engine, metabolism is reduced to the simplistic equation of "calories in, calories out".
    Quote Originally Posted by achoo View Post
    No matter how amusing you may think it is, your straw man violates the laws of conservation of energy.

    If you ingest more calories than you burn, you gain weight. Period. It flat out doesn't matter what's inside - if the energy in is more than the energy out, it MUST go somewhere.

    All the wishful thinking in the universe can't change that.
    While the laws of thermodynamics applies to us, we aren't the same as a car engine. If a car is running efficiently, all of the heat energy that is in a molecule of gasoline is converted and the molecule of gasoline is completely oxidized to carbon dioxide and water. Food...and the human body...doesn't operate that way. We utilized some of the energy of the food and some of it gets passed out of the system. Cars do a little of this in that they shed heat energy they can't use but, for the most part, all of the gasoline that is burned in a internal combustion engine is utilized.

    Cars also don't have mechanisms for storing any excess energy. We have complicated internal mechanisms to convert and store some of the food energy for later use. Since we are individuals from different backgrounds with different genetic histories, some of us are better at converting and storing food energy than others. Follow the link below to a very interesting article on the subject.

    Quote Originally Posted by kevin_stevens View Post
    Yes, it is always the simple equation of calories in/calories out. Physics demands it. The problem is that people are really poor at measuring both. And as the OP points out, different people can do things at different degrees of efficiency.

    But people who want to deny the essential connection between what they put in and what they put out are simply deluding themselves.

    KeS
    It's not that simple. Here's what the American Heart Association has to say

    American Heart Association and the American College of Sports Medicine published joint guidelines for physical activity and health. They suggested that 30 minutes of moderate physical activity five days a week is necessary to “promote and maintain health.” What they didn’t say, though, was that more physical activity will lead us to lose weight. Indeed, the best they could say about the relationship between fat and exercise was this: “It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling.”
    My on experience bears this out. A couple of years ago my company participated in a contest to track minutes of exercise (one point per minute) over a 10 week period. Part of my 10 weeks included a 400 mile bicycle tour. I ended the 10 week period with 10000 points of which 3000 was due to my tour. The next nearest competitor in my group had 7000 points, is skinny as a rail but not a real regular exerciser - she bumped it up for the contest. I lost no weight over the 10 week period but, with the exception of the tour, this is also my normal level of exercise. Add in my tour and I spanked my co-workers. But they continue to be a 'normal' weight while I continue to be overweight.

    The rest of the above article also points out that we aren't black boxes, thermodynamically. We are a complex system that isn't easily boiled down to an energy in/energy out equation.
    Stuart Black
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  10. #60
    Senior Member WonderMonkey's Avatar
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    Quote Originally Posted by Rhodabike View Post
    I have skinny co-workers who don't do any sort of physical activity and can eat whatever they want. (I work in an office.) So clearly it isn't always just the simple equation of calories in/calories out that we've always been told.
    If I ate the way my cubicle mate eats, I'd weigh 300 pounds.
    "Calories out" is whatever you burn doing what you do, to include doing nothing. So the "Calories In / Calories Out" is still a general guideline, it is just that, a general guide. I'd say it handles most of the equation but there are other things to factor in.

  11. #61
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by jimnolimit View Post
    there are legitimate medical situations that can put a person at a disadvantage to losing weight, but i'm willing to bet this is not the case for most overweight people. being lazy, inactive, eating junk food and/or over eating is.
    While that may be the case for some people, those are stereotypes and loaded with much hurtful meaning. As a person who has struggled with weight issues since I was 5 years old, I wasn't particularly inactive as a child and I am far more active as an adult...and have been for 30+ years. Nor have I eaten, nor be able to eat, large quantities of junk food. This old fat man is far more active...and eats more responsibly... than any of his co-workers, family or friends. I have never taken a vacation where I go and lie on a beach. My vacations usually involve weeks of carrying my own gear and moving my own self down the road. Most people would look at me and say that there goes a lazy ******* but none of them will even consider my kind of vacations.
    Stuart Black
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  12. #62
    Senior Member tony_merlino's Avatar
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    We are black boxes, with a relatively deterministic relationship between input, output and state. However, the "transfer function" of that black box, the equation that maps calories input, calories output and grams of fat stored or mobilized is (1) individual, and (2) time varying (albeit slowly).

    If you believe that you get 3500 Kcal of energy from a pound of fat, you're probably wrong. If you believe that riding a bike with a certain cadence for an hour burns exactly X calories, you're probably wrong. But what you CAN know is what those relationships are FOR YOU.

    Talk of fast or slow metabolisms, efficiency, etc is interesting but not useful for losing weight or maintaining weight loss. Learning your own body's transfer function, and then structuring your diet and exercise program around that knowledge, using careful measurements and feedback, regardless of how you feel, is much more useful.
    L'asino di Buridano...

  13. #63
    rugged individualist wphamilton's Avatar
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    Quote Originally Posted by goldfinch View Post
    Not really. There are three things going on. One, your metabolic rate actually is lower. But that isn't a huge number. Two, you become less active outside of exercise. Three, you become more efficient in the activity you do. From the article:

    It means we unconsciously reduce our NEAT and spontaneous activity. It also means we become more efficient in the activity we do; we expend less calories for the same movement. In fact, 35% of the decrease in activity energy expenditure can be attributed to an increase in efficiency. Overall, we move around less, and we become more efficient at the movements we perform. Combined with a decrease in resting metabolic rate, we end up burning over 400 calories per day less than you would expect for someone of our same height, weight, gender, and body composition. This is not only why weight loss eventually plateaus, but also why weight is so easily regained.

    This is the part that was missing for me:
    At reduced weight, muscle work efficiency was increased in both cycle ergometry
    In practical terms would mean that efficiency is increased after a weight loss rather than before a weight loss, and due to physiological factors rather than economy of movement, which is how the thread was reading to me.

    Physiological factors would presumably include moving less mass around.

  14. #64
    Senior Member chandltp's Avatar
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    Quote Originally Posted by cyccommute View Post
    The rest of the above article also points out that we aren't black boxes, thermodynamically. We are a complex system that isn't easily boiled down to an energy in/energy out equation.
    I watched a study on youtube where the slim participants were locked away for 2 weeks and had to eat twice their normal daily intake (around 5000 calories, as I recall). Most of them didn't gain as much body fat as expected, and all of them returned to their pre-study weight easily.

    There's something that goes on in their body that doesn't go on in mine (or others that have a lifetime struggle with weight). I don't know what causes these differences. Is it something from my early childhoood, genetics, something else? I don't know. I can keep weight off after I lose it, but it's always a struggle. If I ate what I wanted, my weight would constantly increase. My hunger doesn't regulate the way it should.

    It's called "Why are Thin People not Fat".

    Watching "The Skinny on Obesity" really seems to describe how my body seems to work to me.

    Low carb eating makes it better, but my body still doesn't regulate well.
    There are 10 types of people, those that understand binary and those that don't.

  15. #65
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by tony_merlino View Post
    We are black boxes, with a relatively deterministic relationship between input, output and state. However, the "transfer function" of that black box, the equation that maps calories input, calories output and grams of fat stored or mobilized is (1) individual, and (2) time varying (albeit slowly).

    If you believe that you get 3500 Kcal of energy from a pound of fat, you're probably wrong. If you believe that riding a bike with a certain cadence for an hour burns exactly X calories, you're probably wrong. But what you CAN know is what those relationships are FOR YOU.

    Talk of fast or slow metabolisms, efficiency, etc is interesting but not useful for losing weight or maintaining weight loss. Learning your own body's transfer function, and then structuring your diet and exercise program around that knowledge, using careful measurements and feedback, regardless of how you feel, is much more useful.
    I agree. What biological units aren't is a heat engine...at least not like mechanical heat engines. You can, relatively easily, calculate and predict what kind of work you can get from putting a measured amount of energy into a mechanical heat engine. You can't necessarily calculate and predict what kind of work you can get from putting a measured amount of energy into a biological unit like a human. Cars don't store energy that they use for later, we humans do. Put an excess of energy into a car and you'll just get a hot car. Put an excess of energy into a human and you may get a human that gains weight. But you may not.

    Planning and structuring your diet and exercise around knowing your body's own energy usage is all well and good but the system varies too much for any predictive ability. Look at the quote from the American Heart Association I posted..."It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling.” What that says to me is that boiling down the problem to am energy in/energy out equation is too simplistic.
    Stuart Black
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  16. #66
    Senior Member tony_merlino's Avatar
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    Quote Originally Posted by cyccommute View Post
    I agree. What biological units aren't is a heat engine...at least not like mechanical heat engines. You can, relatively easily, calculate and predict what kind of work you can get from putting a measured amount of energy into a mechanical heat engine. You can't necessarily calculate and predict what kind of work you can get from putting a measured amount of energy into a biological unit like a human. Cars don't store energy that they use for later, we humans do. Put an excess of energy into a car and you'll just get a hot car. Put an excess of energy into a human and you may get a human that gains weight. But you may not.

    Planning and structuring your diet and exercise around knowing your body's own energy usage is all well and good but the system varies too much for any predictive ability. Look at the quote from the American Heart Association I posted..."It is reasonable to assume that persons with relatively high daily energy expenditures would be less likely to gain weight over time, compared with those who have low energy expenditures. So far, data to support this hypothesis are not particularly compelling.” What that says to me is that boiling down the problem to am energy in/energy out equation is too simplistic.
    I disagree on several points. One (not the major point, but interesting to look at because there are parallels with the way humans work) has to do with the car analogy: Just as we don't input energy to humans directly, we don't input energy directly to the car; we feed it a substance (fuel) that it converts, via a chemical reaction, into energy that it uses to do work, where work is measured by miles driven, load hauled, etc. The car doesn't get bigger if we give it more fuel than it needs to do what we're asking it to do at the moment, but it has a gas tank that can store its "food" until needed for conversion. We do the same.

    And each car converts a gallon of fuel into miles driven (simplifying here) with a different transfer function that relates miles driven per gallon of gasoline input. We're given EPA estimates based on analysis and perhaps some testing on a sample of cars, but we can only know the transfer function of a particular car by measuring the fuel consumed and the miles driven.

    Humans are similar in that respect. You can measure your input pretty exactly. You can measure your weight pretty exactly. And you can estimate your level of activity - not as accurately - but well enough. It's then easy enough to generate a simple relation between calories input and weight, with the general estimate of activity level as a parameter. You get a family of curves, each relating food calories consumed to weight over time, parameterized based on activity level.

    I disagree that the system isn't predictable. I've been tracking calories and measuring weight now for four months. By holding the calories input steady, i.e. not cheating on the diet, and maintaining the same exercise regime, I've been able to predict my (smoothed) weight 30 days into the future with a mean squared error of less than .25 lbs. And predicting the direction of a trend, i.e. up or down, is 100% accurate. Given that daily variations due to water, "solids", etc are larger than my prediction error, I'd say (1) the methodology works pretty well, and (2) the system is pretty predictable.

    The mistake would be to leave out the calibration part, instead using the analog of the EPA estimates for the relations between calories ingested, weight and activity.

    The system does vary over time. But it does this slowly enough that we can adapt our estimate of this "transfer function" pretty well, so that it remains useful.

    Are people who were always thin more active, inefficient, nervous, twitchy, whatever than people like me? I don't know. It doesn't matter. Are people like me, who have always either been losing weight by dieting or gaining weight by eating the way we wanted to eat, different from people who always ate whatever their bodies/minds/emotions told them to eat and never got fat? I don't know - that doesn't matter, either. That won't work for me; I'll never be like that.

    But I do know that my own system, at least from the black box point of view, is knowable enough to allow me to gauge how much I can eat in order to lose weight.
    L'asino di Buridano...

  17. #67
    Senior Member goldfinch's Avatar
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    Tony, when I was losing weight I could also predict my weight going forward pretty dang accurately for about six months. Then I hit a plateau for about a month. At that point I was actually exercising a lot. On the advice of others I upped my calories, kept the exercise level the same, and started losing again. And I started plugging along again, fairly accurately predicting going forward how much I would weigh. This worked until this January, when I had reached my weight loss goal. I upped my calories but was continuing to lose weight and was also losing energy. It has been very tough figuring out with any accuracy how many calories I need. It has been four months now of experimenting. I have quit losing weight and do feel more energetic but I struggle with getting the right number of calories in and have had to vary it over this time period. For the past month I felt like I was starving. During the month I cut down my riding a lot due to travel, weather and an injury. However, I upped my efforts on weight lifting and actually gained a lot of strength in the past month, more than I had over the prior several months. I trended up on weight by .1 pound a week, or 50 calorie excess a day, which may be statistically irrelevant, averaging about 1800 calories a day. That is a huge number for a person who weighs 103 pounds and is more than the calculators tell me to eat. And these calculators estimate my resting metabolic rate at less than 1000 a day. Sometimes I wonder if the worry of over-counting calories leads me to under-count.

    I might continue to allow the trending up of weight if I think that I am building muscle and provided that my waist, bust and hip size does not increase.

  18. #68
    Mad bike riding scientist cyccommute's Avatar
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    Quote Originally Posted by tony_merlino View Post
    I disagree on several points. One (not the major point, but interesting to look at because there are parallels with the way humans work) has to do with the car analogy: Just as we don't input energy to humans directly, we don't input energy directly to the car; we feed it a substance (fuel) that it converts, via a chemical reaction, into energy that it uses to do work, where work is measured by miles driven, load hauled, etc. The car doesn't get bigger if we give it more fuel than it needs to do what we're asking it to do at the moment, but it has a gas tank that can store its "food" until needed for conversion. We do the same.
    Your "food" analogy for a car is too simplistic...as are most car/human energy analogies. The fuel in a car converts chemical energy into heat energy as you said. However, that's the only thing it does. When you power down the car, it doesn't use, nor need, any of that energy to exist. There may be reserve energy in the tank but it's not needed for anything other than powering the unit for future use.

    Humans, and all biological organism, have a constant need for energy and have elaborate mechanisms to take in energy, store it and then release it when needed. However we can't predict when that future use is or how much is needed so that organism puts away more than it will need. Bacterium do this, algae does this, bears do it, and humans do it too. All biological units just happen to carry the reserves within the organism. To get the proper car analogy, you would have to make the car bigger each time you filled the tank because there would be the immediate need and then there would be reserves carried for future use. In fact you could think of a filling station, a fuel storage tank and a refinery as the 'obese' side of your automobile. Without that ability to store and access fuel at some future date, you car would be useless.


    Quote Originally Posted by tony_merlino View Post
    And each car converts a gallon of fuel into miles driven (simplifying here) with a different transfer function that relates miles driven per gallon of gasoline input. We're given EPA estimates based on analysis and perhaps some testing on a sample of cars, but we can only know the transfer function of a particular car by measuring the fuel consumed and the miles driven.

    Humans are similar in that respect. You can measure your input pretty exactly. You can measure your weight pretty exactly. And you can estimate your level of activity - not as accurately - but well enough. It's then easy enough to generate a simple relation between calories input and weight, with the general estimate of activity level as a parameter. You get a family of curves, each relating food calories consumed to weight over time, parameterized based on activity level.
    The level of activity is the rub. We say that we are running on empty when we are tired or at the end of physical activity, however we really aren't running on empty because we are still functioning. Death is the ultimate empty tank.

    The other problem with simplifying the system too much is that you don't take into account the various feedback loops within biological systems. Once you've reached a certain weight level, the systems are going to do whatever they can to maintain that weight. A recent study...I can't find it right now...says that weight loss is difficult to maintain because the body will utilize all of it's mechanisms to get back to the previous equilibrium even years later. In other words, you'll have to maintain a lower caloric input than a person who didn't gain weight just to maintain the weight loss.


    Quote Originally Posted by tony_merlino View Post
    I disagree that the system isn't predictable. I've been tracking calories and measuring weight now for four months. By holding the calories input steady, i.e. not cheating on the diet, and maintaining the same exercise regime, I've been able to predict my (smoothed) weight 30 days into the future with a mean squared error of less than .25 lbs. And predicting the direction of a trend, i.e. up or down, is 100% accurate. Given that daily variations due to water, "solids", etc are larger than my prediction error, I'd say (1) the methodology works pretty well, and (2) the system is pretty predictable.
    Four months isn't much time in terms of weight loss. Your predictions of weight loss will deviate more from your curves with more time. Again, we aren't like cars. I can predict what my gas mileage will be today, tomorrow and probably 20 years into the future. But try to predict what your weight will be 20 years into the future. If you pick something close to the weight you had before you started losing weight, you'll probably be closer than if you pick your lowest weight.
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    Goldfinch, forget the calorie calculators - they assume things about how we convert food into fat and energy, and how much energy exercise expends, based on theory and averages. Feedback is the only way to know how these things happen for you. Some points:

    1) The system is time varying, albeit slowly. When your predictions don't work, it's time to recalibrate. When you hit a plateau, it means that your transfer function has changed. At that point, you need to vary the inputs to be able to derive the new transfer function. Whether this change has been caused by some metabolic adaptation or by some subtle change in "efficiency of motion" in your non-exercise time is really not important. We could come up with all sorts of plausible explanations for your plateau that was ended by eating more (even that you then had enough energy to be less efficient in your non-exercise time). But what good does that kind of speculation do?

    2) You can (and should) measure input (calories consumed) and state (weight) as accurately as possible, and do this often enough (every day) to smooth out the noise of daily fluctuations. You can roughly estimate your overall activity level, but this estimate is only a starting point for calibration - as you've pointed out in earlier posts, there are all sorts of things operating, e.g. efficiency and quantity of motion in non-exercise time, the work of schlepping (or not) an obese body around...

    When we roughly estimate our activity level, we're really estimating more than that - we're estimating the combined effects of metabolic adjustments, efficiency, exercise, etc. That's why schemes that try to assign exact values to calories expended by activity fail so badly - they don't take into account the other stuff. And they can't - those things are not observable by any reasonable means.

    But you don't have to take those things into account, if you're doing a good job measuring the things you can measure (calories in and weight). Even without any sort of model, you can pretty much tell whether your overall lifestyle has changed within the last 30 days. (I sort of assume that we don't vary that so much over that period of time, so the last 30 days have excellent predictive value for the next 30 days.) A linear predictive scheme, using the last 30 days as the observation window, is both sensitive and robust enough to measure the direction of the trend and to give a meaningful prediction for the next 30.

    Calorie deficit/excess is a little trickier to estimate. For that, I use a model based on the Active Metabolic Rate formula that you can find all over online, but adjusted to minimize the mean squared error between weights predicted by the model and my measured weights, based on an assumption of an "activity profile". (I use a model in between "light exercise" and "moderate exercise", just because it fit best as a starting point.) I then apply a calibration factor to fit my weights to the curve. For me, right now, the calibration factor is right around 1.2, that is, my body loses weight at a rate 1.2 times that predicted by the 3500 Calories = 1 lb rule of thumb. But that calibration factor will probably have to change as my system changes.

    If you're interested, I could send you formulas. Right now, my spreadsheets are hard-coded to use the AMR formulas for men. (The linear prediction estimates are gender neutral.) If you'd like, I could hack up a version for women and send that to you. (It won't happen in the next few days, though - really busy at work...)

    Bottom line: Our bodies/minds are complex, mostly unobservable things, and we can't know them directly. The only thing we can do is try to determine our individual, time varying mapping between inputs and state, with the effects of activity/metabolism/etc used as a parameter that is adapted in response to the observed input/state relation, and to use what we observe as feedback to vary the inputs so that the state stays in a desired range.
    Last edited by tony_merlino; 05-02-12 at 08:46 AM.
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    Note for cyccocommute: I'm not trying to predict 20 years or even 6 months in advance (although the prediction error out a few months is very low.) It's sufficient to gauge the trend 30 days in advance, which I'd guess you'd agree is very doable. The success of any scheme is to (1) measure input and state as well as you can, and (2) use those measurements in a feedback loop to control the system. If you stop doing that, obviously, the system is no longer under control and all bets are off.
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    Quote Originally Posted by tony_merlino View Post
    If you're interested, I could send you formulas. Right now, my spreadsheets are hard-coded to use the AMR formulas for men. (The linear prediction estimates are gender neutral.) If you'd like, I could hack up a version for women and send that to you. (It won't happen in the next few days, though - really busy at work...)
    Yes, I am interested. I know that you are time crunched so whenever you can it would be great. Your feedback has been helpful to me. I have been doing daily weight and calorie tracking for a couple of months now.

    I got calorie guesstimates from using "moderate exercise" models and got estimated calories of 1480 (based on resting metabolic rate) and (1720 based on basal metabolic rate). My 1800 seems high but given my strength building maybe it isn't out of line. As you say, the calories out estimate is the hardest to make. The best tools seem to be daily weight and calorie recording and watching trends.

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    Quote Originally Posted by cyccommute View Post
    . A recent study...I can't find it right now...says that weight loss is difficult to maintain because the body will utilize all of it's mechanisms to get back to the previous equilibrium even years later. In other words, you'll have to maintain a lower caloric input than a person who didn't gain weight just to maintain the weight loss.
    Yes, I have read the studies too. I sometimes use the example of a friend of mine who is about my size but never has gained weight. She has always worn the same size clothes as she did when we were in college together in the early 70s. Late last fall we went to a restaurant together and had the same meal. She was stuffed and said she felt bloated after the meal. I said I could have eaten the same meal twice. I did not feel full and certainly not bloated.

    Because I am countering biology I think using tools like Tony discusses very helpful. Daily weighing and calorie counting and watching trends to catch myself before I am lost. What I am struggling with right now is building strength. I do not like to see the scale go up but I might have to allow a bit of that to increase my lean body mass. I am sure that I still have too high a fat to muscle ratio. It has been harder than I thought it would be to judge how much to eat when there is no real good way to measure body lean vs. fat mass beyond taking body measurements and judging strength. Is the scale trending up slightly because I am getting fat? Or because I am getting more muscle mass? That will be the issue.

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    It's not a myth, some people have different basal metabolic rates.

    You can change yours, for example, by adding muscle. A pound of muscle burns more calories than a pound of fat. The more muscle you have, the more calories you burn-even at rest.

    Other things can negatively impact your metabolism. If your diet does not have enough iodine in it, you can develop hypothyroidism. This is related to the T3 and T4 thyroid hormones, which may themselves affect the metabolism with or without iodine.

    A low testosterone level may also affect your energy level, although I don't know if it affects the metabolism directly. I began HRT after being diagnosed with low testosterone, and my energy level and fat-burning ability skyrocketed.

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    Quote Originally Posted by MadCityCyclist View Post
    It's not a myth, some people have different basal metabolic rates.

    You can change yours, for example, by adding muscle. A pound of muscle burns more calories than a pound of fat. The more muscle you have, the more calories you burn-even at rest.

    Other things can negatively impact your metabolism. If your diet does not have enough iodine in it, you can develop hypothyroidism. This is related to the T3 and T4 thyroid hormones, which may themselves affect the metabolism with or without iodine.

    A low testosterone level may also affect your energy level, although I don't know if it affects the metabolism directly. I began HRT after being diagnosed with low testosterone, and my energy level and fat-burning ability skyrocketed.
    This all may be true. The way that you know what's true for you is by measuring and applying feedback. Otherwise, it's just theory.

    Goldfinch: The muscle vs. fat thing is pretty complicated, but not as mysterious as people make it out to be. The best way to measure body fat percentage is by the immersion method (comparing dry weight to weight while immersed in water). But you can get a rough idea using a calculator that looks at your weight, waist size, and for a woman, wrist, hips and forearm. I don't believe it's 100% accurate or even close, but it's probably good enough.

    But that's all an aside. If you're out to REPLACE fat with muscle, then the difference you'll see is very slight until you get to mega-athlete status. Consider this:

    If you're a woman at a pretty healthy weight, you're probably running between 25% - 30% body fat percentage. Let's say you want to get that down to somewhere around 21%, which is considered on the border between "fitness" and "athlete" according to the American council on Exercise Guidelines.

    At 115 lbs, if you currently have a body fat percentage of 25%, you'd be looking at reducing the fat that currently weighs 28.75 lbs to 23 lbs, for a loss of 5.25 lbs. You'd want to replace this with muscle tissue that weighs 18% more than the fat it's replacing, so your net increase in weight would be about one pound. Almost nothing.

    If your current body fat percentage is 30%, (which is highly unlikely given all the weight you lost - 30% is considered borderline obese for women), and you still want to get to 20%, it becomes a difference of about 2 lbs. Remember, this happens slowly - building muscle doesn't happen overnight. And all of this is still assuming that you're replacing fat with muscle, liter per liter.

    Bottom line: I'd neither look for nor accept major changes on the scale as a result of this muscle-building exercise if I were in your shoes.
    Last edited by tony_merlino; 05-02-12 at 12:22 PM.
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    Thanks Tony. I wasn't thinking so much about the muscle being more dense as much as thinking about how to fuel muscle gain. I erred when losing weight by doing only cardio until late last fall when I started working some with weights. I was really weak. Even though I lost weight slowly I believe my muscle mass suffered during my weight loss. Using one measurement method (neck, waist, hips, wrist and forearm) I think that my body fat is roughly 27% (!!!) and I weigh 104. That means 28 pounds of fat and all of 76 pounds of lean mass. But I wonder whether it is possible to lose that fat and gain muscle on a nearly one to one ratio. To build muscle you need a calorie surplus. To burn fat you need to need a calorie deficit. How much of that fat can be used for calories and still build muscle? I guess I'll find out.

    Just thinking out loud. I should read up on this. I do know that there are studies that show resistance training while losing weight preserves muscle mass (I should have read that a year ago!). What I don't know is how much you can increase muscle mass and lose fat at the same time.
    Last edited by goldfinch; 05-02-12 at 08:36 PM.

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