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This is not a "misunderstanding" on my end. I know quite a bit about nutrition science and exercise physiology. There are a large number of people who honestly

This is not a "misunderstanding" on my end. I know quite a bit about nutrition science and exercise physiology. There are a large number of people who honestly believe that the laws of thermodynamics can be trumped by human biology, excluding any and all externalities. The OP made a statement that may place him in that category. If you want to talk about satiety, diet patterns, behavior remapping, nutrient partitioning, fat/muscle ratios, glycogen stores, or other advanced topics, feel free. But the idea that thermodynamics do not govern 85% (being very generous here) of the effectiveness of a weight loss program is willful self-delusion.

jvrossb 12y ago
I think the idea is that 10 grams of sugar for example may get broken down by person A in such a way as to generate 40 calories whereas person B might only generate 30. No violation of the laws of thermodynamics there.
- scotty79 12y ago
  Just violation of basic biochemistry, I suppose.
  - logfromblammo 12y ago
    Absorption of food energy from food is affected by several factors, including the proportions of different species of microbes inside the intestines. Sucrose sugar will be more uniformly absorbed, as the enzymes required to break it down into fructose and glucose are nearly universal. Glucose metabolism is fundamental to animal physiology. Fructose metabolism is about the same for all humans. For something like the lactose in cow's milk, the relative metabolic impact for different humans can vary greatly. Some people can metabolize it directly. In others, gut bacteria must digest it into a usable form first. For those people, the composition of their gut flora will determine how efficiently the food energy from lactose is absorbed by their bodies. That is how the energy calculated by complete combustion in a bomb calorimeter might differ significantly from the energy added to a biological organism. That calorimeter value is essentially the upper limit for "calories in". Using that value means that you still have an unknown value for digestion and metabolism inefficiency in the "calories out" column. This is why counting "calories in" and "calories out" does not work as expected. The former can be determined easily with the aforementioned calorimeter. But the latter is a complex function that includes "calories in" as an input parameter. You would literally have to wear measurement devices on your body 24 hours a day in a controlled environment, and use special toilets to ever know exactly what your "calories out" numbers are. You would have to calculate thermal losses, water balance, and gas exchange. This is simply not practical for anyone. Recommending it is madness. It is far more useful to experimentally determine, on a per-person basis, the actions and activities that result in changes in body composition, do the ones that cause adverse changes less, and the ones that cause desired changes more. There are very few recommendations that work the same way for everyone. But for people that want to reduce their body fat percentage, some stand out. Consume fewer monosaccharides, disaccharides, and trisaccharides. Do strength exercises regularly. Do cardio exercises regularly. Following those three recommendations often achieve the desired results without the need to count calories. But other ways are possible, some of which are not universally applicable to all humans. In the absence of sophisticated measurement equipment, it is more practical to simply experiment, using plausible hypotheses, until the desired results are achieved. Do what works. Avoid what does not work. Your results will vary from other animals with different biochemical responses, including other humans that may be closely related to you genetically.
    - scotty79 12y ago
      I guess I got misunderstood. I was commenting on the claim that 10 grams of sugar may give different amount of calories when broken down by different persons. I've made some assumptions perhaps to hastily that he meant table sugar and by broken down he meant going in full, through the whole route in which body processes sucrose. If at some stage some part of sucrose is not broken down then you can't count it towards 10 gram. It seems like cheating but assuming the opposite would be like claiming that you can affect breaking down of sucrose by taking it with healthy amount of laxative or dropping some from your mouth as you are munching it. Besides you said yourself that sucrose, glucose and fructose are pretty much processed by all humans at about the same rate. Considering all that, claiming that you can get significantly different amounts of energy from (table) sugar would be claiming that basic biochemistry is different for different people (and it's not). I'm not entirely sure about what you said, that measuring calories spent is so hard. Energy is mostly turned to heat eventually, which is expelled with air you breathe out and the sweat. You could probably estimate the rate of sweating, rate of breathing out, temperature differences, how much sweat evaporated to calculate a lower bound on how much energy a person spent. It's nice that you can measure upper bound on calories absorbed and lower bound on calories spent. You just match the two and observe if person is dying of starvation or not. If not, then you have got a diet. Write a book and make few persons happy and very many unhappy and some thinner.
      - logfromblammo 12y ago
        You can't stop with sucrose in the intestines. Once that sucrose is split into fructose, which goes to the liver for additional processing, and glucose, which goes into the bloodstream, you have to deal with the individual's hormonal responses. You have insulin, leptin, ghrelin, and a host of other signaling chemicals, and they all interact with each other and with specific areas of the nervous system. Give 10g sucrose to one person, and they may bounce off the walls for a few minutes (increasing caloric expenditure). Give 10g to someone else, and they may feel an urge to eat more (increasing caloric intake). Try it on a third person, and they may want to take a nap (decreasing caloric expenditure). The chemicals in foods can act upon the body's biochemistry in as drastic a manner as pharmaceutical drugs, together with side effects. People that just consumed large amounts of ethanol have different eating and activity patterns than those who have not. The drunkenness is obvious, but the Buffalo wing consumption still varies. Sugar intake influences metabolism, just like drugs such as caffeine, nicotine, ethanol, or epinephrine, though those are active at far lower doses. Thus, the thermodynamic equation of "energy_in - energy_out = delta energy_stored" is certainly valid at a technical level, but it has no practical utility for weight loss. Both energy in and energy out are black box functions that vary by individual, and include types and quantities of foods eaten and current fat stores as input parameters. The black boxes are not currently well understood. The genome has already been sequenced, but that only led to epigenetics and proteomics. As research in those areas proceeds, we might see a magic pill for fat people that reprograms their black boxes to be more like athletic people. Until then, their effort to lose weight will be a conscious struggle against the natural inclinations of their own body. And they will continue to be judged as deficient by people who do not need to consciously oppose the biochemical signals of their own bodies, and are therefore ignorant of what that may entail. This is why weight loss is a touchy subject for some people. If you can't be unambiguously supportive and encouraging to someone trying to get fit, it is usually better to just maintain your distance and pretend to not have an opinion. A person who has lost 100 kg will have a far greater understanding of what is involved than someone who has never even tipped the scales past 100 kg in total. And even that person may not understand all that another 200 kg person has to overcome to lose half their body weight. So here's what you say: "Good for you! You're already a winner! I know you have the ability to reach your goals!" You don't suggest that they could do better by buying more accurate or more precise scales. They aren't fat because they were lax in their data collection protocols. The stoichiometry of inhaled oxygen and exhaled carbon dioxide won't help. Taking body temperature and recording urine and sweat volume won't help. Anecdotes about how you lost your weight won't help. If you aren't currently activating genes or folding proteins as part of your regular job or primary hobby, you're better off simply providing the psychological support to just keep trying, without getting into specifics.
danielbarla 12y ago
Honest question - how good a fit / approximation is the concept of a calorie (as in, we burn the material in question, and measure energy given off as heat) in approximating the energy extracted from the material through digestion? Obviously the laws of thermodynamics hold, but I find the above equality to be slightly presumptuous - an obvious exception is that "fiber" can be burnt, but not digested (by humans, at least). What other caveats are there to this system, and are they employed to adjust calorie numbers for foodstuffs? I'm genuinely curious to know more about this, are there any good, concise sources?
- nkuttler 12y ago
  You may want to start with http://en.wikipedia.org/wiki/Thermic_effect_of_food http://en.wikipedia.org/wiki/Thermic_effect_of_food. Thermodynamics are mostly useless when you look at nutrition, even if they are true. The same amount of calories from different sources get metabolized differently, have different effects on satiety, insulin, and a whole host of other factors. Nutrition is biochemistry, not physics. Sure, you will lose weight if you reduce calories. But that information is about as useful as general relativity when you want to throw a ball to another player.
beagle3 12y ago
> But the idea that thermodynamics do not govern 85% It does govern 100%, in a technically useless sense. If it was just thermodynamics, you'd be able to drink hydrocarbons (e.g. gasoline) for food. In a bomb calorimeter, it's as good as carbs or fat, only denser. Or you'd just eat wood or paper. Cellulose is, after all, a carbohydrate! But it's not that simple. - See e.g. this article: http://www.princeton.edu/main/news/archive/S26/91/22K07/index.xml?section=topstories http://www.princeton.edu/main/news/archive/S26/91/22K07/inde... - It does not mention control for "calories out", but assuming rats just do what rats do - it indicates that food composition goes much deeper than calorie intake. - some cells some time use fermentation instead of oxidation, which gets much less energy from food (about 1/6 if I recall correctly). Mostly in tumors, but not only in them. - Some people can apparently get ~2kcal/gr from fiber carbs, where others cannot. People of Japanese origin, in particular, http://www.nature.com/news/2010/100407/full/news.2010.169.html http://www.nature.com/news/2010/100407/full/news.2010.169.ht... - but this is just the most studied example, not the only one. - Atwater factors, which everyone uses to estimate intake often based on 100 year old tables, are horribly inaccurate, e.g. http://www.ncbi.nlm.nih.gov/pubmed/18065582 http://www.ncbi.nlm.nih.gov/pubmed/18065582 (4%-11% error) http://www.ncbi.nlm.nih.gov/pubmed/22760558 http://www.ncbi.nlm.nih.gov/pubmed/22760558 (32% error) - Actual digestion processes depend on enzyme availability, the supply of which lags demand by up to 3 weeks (and tails by up to 6 months), and apparently depends nontrivially on olfactory clues whereas most models assume everything about nutrition and digestion is static. e.g, if you start daily drinking of a gallon of fat you haven't had in the last 6 months, you're going to put most of it out in the bathroom until your body ramps up production of some relevant enzymes, which can take a few days and up to 3 weeks. - Simple stated, "a calorie is a calorie" violates the second law of thermodynamics. See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC506782/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC506782/ ; It's not from Richard P. Feynman - it's from a Richard D Feinman, btw. So, yes, thermodynamics reigns supreme but your ability to estimate your actual calorie intake is very crude. Similarly for your expenditure. The result being, two people can basically eat the same food and do the same kind of activity, and still have significantly different energy balance.
- JoeAltmaier 12y ago
  Assuming all that. It is still 100% true that any subject who consumes less food than they did before, will intake fewer calories and lose weight.

jvrossb 12y ago

I think the idea is that 10 grams of sugar for example may get broken down by person A in such a way as to generate 40 calories whereas person B might only generate 30. No violation of the laws of thermodynamics there.

scotty79 12y ago
Just violation of basic biochemistry, I suppose.
- logfromblammo 12y ago
  Absorption of food energy from food is affected by several factors, including the proportions of different species of microbes inside the intestines. Sucrose sugar will be more uniformly absorbed, as the enzymes required to break it down into fructose and glucose are nearly universal. Glucose metabolism is fundamental to animal physiology. Fructose metabolism is about the same for all humans. For something like the lactose in cow's milk, the relative metabolic impact for different humans can vary greatly. Some people can metabolize it directly. In others, gut bacteria must digest it into a usable form first. For those people, the composition of their gut flora will determine how efficiently the food energy from lactose is absorbed by their bodies. That is how the energy calculated by complete combustion in a bomb calorimeter might differ significantly from the energy added to a biological organism. That calorimeter value is essentially the upper limit for "calories in". Using that value means that you still have an unknown value for digestion and metabolism inefficiency in the "calories out" column. This is why counting "calories in" and "calories out" does not work as expected. The former can be determined easily with the aforementioned calorimeter. But the latter is a complex function that includes "calories in" as an input parameter. You would literally have to wear measurement devices on your body 24 hours a day in a controlled environment, and use special toilets to ever know exactly what your "calories out" numbers are. You would have to calculate thermal losses, water balance, and gas exchange. This is simply not practical for anyone. Recommending it is madness. It is far more useful to experimentally determine, on a per-person basis, the actions and activities that result in changes in body composition, do the ones that cause adverse changes less, and the ones that cause desired changes more. There are very few recommendations that work the same way for everyone. But for people that want to reduce their body fat percentage, some stand out. Consume fewer monosaccharides, disaccharides, and trisaccharides. Do strength exercises regularly. Do cardio exercises regularly. Following those three recommendations often achieve the desired results without the need to count calories. But other ways are possible, some of which are not universally applicable to all humans. In the absence of sophisticated measurement equipment, it is more practical to simply experiment, using plausible hypotheses, until the desired results are achieved. Do what works. Avoid what does not work. Your results will vary from other animals with different biochemical responses, including other humans that may be closely related to you genetically.
  - scotty79 12y ago
    I guess I got misunderstood. I was commenting on the claim that 10 grams of sugar may give different amount of calories when broken down by different persons. I've made some assumptions perhaps to hastily that he meant table sugar and by broken down he meant going in full, through the whole route in which body processes sucrose. If at some stage some part of sucrose is not broken down then you can't count it towards 10 gram. It seems like cheating but assuming the opposite would be like claiming that you can affect breaking down of sucrose by taking it with healthy amount of laxative or dropping some from your mouth as you are munching it. Besides you said yourself that sucrose, glucose and fructose are pretty much processed by all humans at about the same rate. Considering all that, claiming that you can get significantly different amounts of energy from (table) sugar would be claiming that basic biochemistry is different for different people (and it's not). I'm not entirely sure about what you said, that measuring calories spent is so hard. Energy is mostly turned to heat eventually, which is expelled with air you breathe out and the sweat. You could probably estimate the rate of sweating, rate of breathing out, temperature differences, how much sweat evaporated to calculate a lower bound on how much energy a person spent. It's nice that you can measure upper bound on calories absorbed and lower bound on calories spent. You just match the two and observe if person is dying of starvation or not. If not, then you have got a diet. Write a book and make few persons happy and very many unhappy and some thinner.
    - logfromblammo 12y ago
      You can't stop with sucrose in the intestines. Once that sucrose is split into fructose, which goes to the liver for additional processing, and glucose, which goes into the bloodstream, you have to deal with the individual's hormonal responses. You have insulin, leptin, ghrelin, and a host of other signaling chemicals, and they all interact with each other and with specific areas of the nervous system. Give 10g sucrose to one person, and they may bounce off the walls for a few minutes (increasing caloric expenditure). Give 10g to someone else, and they may feel an urge to eat more (increasing caloric intake). Try it on a third person, and they may want to take a nap (decreasing caloric expenditure). The chemicals in foods can act upon the body's biochemistry in as drastic a manner as pharmaceutical drugs, together with side effects. People that just consumed large amounts of ethanol have different eating and activity patterns than those who have not. The drunkenness is obvious, but the Buffalo wing consumption still varies. Sugar intake influences metabolism, just like drugs such as caffeine, nicotine, ethanol, or epinephrine, though those are active at far lower doses. Thus, the thermodynamic equation of "energy_in - energy_out = delta energy_stored" is certainly valid at a technical level, but it has no practical utility for weight loss. Both energy in and energy out are black box functions that vary by individual, and include types and quantities of foods eaten and current fat stores as input parameters. The black boxes are not currently well understood. The genome has already been sequenced, but that only led to epigenetics and proteomics. As research in those areas proceeds, we might see a magic pill for fat people that reprograms their black boxes to be more like athletic people. Until then, their effort to lose weight will be a conscious struggle against the natural inclinations of their own body. And they will continue to be judged as deficient by people who do not need to consciously oppose the biochemical signals of their own bodies, and are therefore ignorant of what that may entail. This is why weight loss is a touchy subject for some people. If you can't be unambiguously supportive and encouraging to someone trying to get fit, it is usually better to just maintain your distance and pretend to not have an opinion. A person who has lost 100 kg will have a far greater understanding of what is involved than someone who has never even tipped the scales past 100 kg in total. And even that person may not understand all that another 200 kg person has to overcome to lose half their body weight. So here's what you say: "Good for you! You're already a winner! I know you have the ability to reach your goals!" You don't suggest that they could do better by buying more accurate or more precise scales. They aren't fat because they were lax in their data collection protocols. The stoichiometry of inhaled oxygen and exhaled carbon dioxide won't help. Taking body temperature and recording urine and sweat volume won't help. Anecdotes about how you lost your weight won't help. If you aren't currently activating genes or folding proteins as part of your regular job or primary hobby, you're better off simply providing the psychological support to just keep trying, without getting into specifics.

danielbarla 12y ago

Honest question - how good a fit / approximation is the concept of a calorie (as in, we burn the material in question, and measure energy given off as heat) in approximating the energy extracted from the material through digestion? Obviously the laws of thermodynamics hold, but I find the above equality to be slightly presumptuous - an obvious exception is that "fiber" can be burnt, but not digested (by humans, at least). What other caveats are there to this system, and are they employed to adjust calorie numbers for foodstuffs? I'm genuinely curious to know more about this, are there any good, concise sources?

nkuttler 12y ago
You may want to start with http://en.wikipedia.org/wiki/Thermic_effect_of_food http://en.wikipedia.org/wiki/Thermic_effect_of_food. Thermodynamics are mostly useless when you look at nutrition, even if they are true. The same amount of calories from different sources get metabolized differently, have different effects on satiety, insulin, and a whole host of other factors. Nutrition is biochemistry, not physics. Sure, you will lose weight if you reduce calories. But that information is about as useful as general relativity when you want to throw a ball to another player.

beagle3 12y ago

> But the idea that thermodynamics do not govern 85% It does govern 100%, in a technically useless sense. If it was just thermodynamics, you'd be able to drink hydrocarbons (e.g. gasoline) for food. In a bomb calorimeter, it's as good as carbs or fat, only denser. Or you'd just eat wood or paper. Cellulose is, after all, a carbohydrate! But it's not that simple. - See e.g. this article: http://www.princeton.edu/main/news/archive/S26/91/22K07/index.xml?section=topstories http://www.princeton.edu/main/news/archive/S26/91/22K07/inde... - It does not mention control for "calories out", but assuming rats just do what rats do - it indicates that food composition goes much deeper than calorie intake. - some cells some time use fermentation instead of oxidation, which gets much less energy from food (about 1/6 if I recall correctly). Mostly in tumors, but not only in them. - Some people can apparently get ~2kcal/gr from fiber carbs, where others cannot. People of Japanese origin, in particular, http://www.nature.com/news/2010/100407/full/news.2010.169.html http://www.nature.com/news/2010/100407/full/news.2010.169.ht... - but this is just the most studied example, not the only one. - Atwater factors, which everyone uses to estimate intake often based on 100 year old tables, are horribly inaccurate, e.g. http://www.ncbi.nlm.nih.gov/pubmed/18065582 http://www.ncbi.nlm.nih.gov/pubmed/18065582 (4%-11% error) http://www.ncbi.nlm.nih.gov/pubmed/22760558 http://www.ncbi.nlm.nih.gov/pubmed/22760558 (32% error) - Actual digestion processes depend on enzyme availability, the supply of which lags demand by up to 3 weeks (and tails by up to 6 months), and apparently depends nontrivially on olfactory clues whereas most models assume everything about nutrition and digestion is static. e.g, if you start daily drinking of a gallon of fat you haven't had in the last 6 months, you're going to put most of it out in the bathroom until your body ramps up production of some relevant enzymes, which can take a few days and up to 3 weeks. - Simple stated, "a calorie is a calorie" violates the second law of thermodynamics. See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC506782/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC506782/ ; It's not from Richard P. Feynman - it's from a Richard D Feinman, btw. So, yes, thermodynamics reigns supreme but your ability to estimate your actual calorie intake is very crude. Similarly for your expenditure. The result being, two people can basically eat the same food and do the same kind of activity, and still have significantly different energy balance.

JoeAltmaier 12y ago
Assuming all that. It is still 100% true that any subject who consumes less food than they did before, will intake fewer calories and lose weight.