6 ms·

There seems to be a pervasive unwillingness to understand the nature of positive feedback cycles, and instead we're just continually hearing "fat because of int

by Udo 12y ago

There seems to be a pervasive unwillingness to understand the nature of positive feedback cycles, and instead we're just continually hearing "fat because of intake" and "intake because of fat" arguments that try to fall on an extreme interpretation of simplified causality. This article belongs to the very few that actually do a job of describing a feedback cycle, but then it falls short and does the popular simplification thing. Fat cells emit hormones that cause hunger, and they actually do require energy for upkeep. The body prioritizes not losing any of its substance, so most "healthy" adults will always at least eat the amount they need to not lose weight. On top of that come fatal breakages in the messaging system the body uses to control the flow of energy. Fat people are prone to insulin resistance, physical extension of their digestive system that leads to the urge for more throughput, and other mechanisms - all of which cause an almost insurmountable desire to eat a lot. It's an addiction that subverts two of our most powerful mental priorities: the reward/pleasure system and the survival instinct. In most people there is not a lot that can be done to overcome what these two systems tell you. That's why diets fail: my body is lying to me. It's like getting two popup alert boxes every minute, one saying "you are DYING! eat something" and the other goes "you're unhappy, eat something, you deserve some happiness".

SatoshiPacioli 12y ago
There's a wealth of information on ketogenic (low to no carb) diets: http://www.reddit.com/r/keto http://www.reddit.com/r/keto Everyone serious about this understands that carbs are the problem.
- ajcarpy2005 12y ago
  Or for underweight people, part of the solution.
- steeve 12y ago
  I came here to post this. I wish people knew more about keto.
- mistermann 12y ago
  Also, most people have no idea the type and variety of foods you can continue to eat while on an extreme low carb diet: http://www.reddit.com/r/ketorecipes/top/ http://www.reddit.com/r/ketorecipes/top/
- jasallen 12y ago
  ultra-low to no carb on a daily basis has severe issues with it as well. Things like carb-cycling, or low (but not ultra-low) attempt to address those issues. The main points being (1) brain needs glucose, can't fuel any other way (2) glucose is needed for maximum muscle response so if you are fit/athletic in any way you can be short-changing your performance if you have no glycogen stores to tap for "burst fuel"
  - hollerith 12y ago
    >brain needs glucose, can't fuel any other way Not so: the brain can be fueled by ketone bodies, which the liver can create from fat. P.S. I agree with your larger point that avoiding all carbs for many days at a time should only be done by people who have informed themselves of the risks (acidosis and kidney stones).
    - mixmastamyk 12y ago
      What did humans do before large numbers of carbs were widely available? Die of kidney stones? Or perhaps this is because modern people have become accustomed to them being available?
      - merrua 12y ago
        There is carbs in vegetables. Beans too. Just not as much in most of them as grains.
  - sgt101 12y ago
    If you are "tapping for burst fuel" why are you worrying about your diet (apart from the sensible am I having good things enough worry...) Surely these diets are aimed at people who need to loose >10% of body weight ?
- stinos 12y ago
  Care to also post links to scientific evidence next to the reddit? Sure it has information, but from a quick glance it's information without much science/proof to back it up, from people who are already convinced. I think way more is needed to convince the rather critical spirits on HN :)
  - desigooner 12y ago
    Lyle McDonald's e-book on Ketogenic Diet is probably the best thing I've ever read. It's well referenced and pretty comprehensive. http://www.bodyrecomposition.com/the-ketogenic-diet http://www.bodyrecomposition.com/the-ketogenic-diet
  - Nimi 12y ago
    AFAIK, there are several experimental results supporting low carb diets, but all are refutable, as in someone can always come up with a counter-argument. Robert Lustig and his "Sugar: The Bitter Truth" lecture (available on youtube) is probably currently the best-supported argument. There's an initiative called the "Nutrition Science Initiative" (nusi.org) that apparently attempts to put an end to the debate with irrefutable research, which will finally convince everyone one way or the other. They seem to be still in the early stages.
NIL8 12y ago
Very well said. The consequences would be immense if we could override even one of these triggers.
robert_tweed 12y ago
I'm not sure I agree that this article falls short and does the popular simplification thing. It's the first widely accessible article I've seen that clearly refutes (with data and a citation) the oft-repeated assertion that "a calorie is a calorie". Because the science is still incomplete, the article unsurprisingly ends on a "more research is needed" note, but I completely agree with that! While your point about fat cells, ghrelin and leptin has some factual basis, precisely how these hormones affect eating patterns and are themselves affected by bodyfat, carbohydrate intake and insulin resistance, are among the things that need more carefully controlled studies. I'd also like to see more science into the effects of intermittent fasting. There is IIRC only one actual study on this, far from enough to back up all the various protocols and broscience articles on how "fasting is good for you". Anecdotally, it seems to be very effective for some people but I don't think we yet have a very good understanding of why that is, or indeed whether it is even true under controlled conditions. I personally suspect that carb restriction and intermittent fasting both have very similar effects on this group of 3 hormones, while sugar has basically the opposite effect. What's lacking however is clear scientific evidence of this.
jasallen 12y ago
I really did enjoy this article. I don't think there is anything new here, but it's presented in a very "mass media friendly" way, which is important for finally defeating the "just eat less" mentality. Of course, it is still calorie in, calorie out, but we need to understand what effects metabolic changes in our body if we want to understand what calories are going out. Furthermore, quality of life generally indicates most people don't want to shut their metabolism down even if it did mean weight loss -- we want to be energy using machines that are motivated to "get up and do stuff", so just blindly reducing calories is not the path to that. Calorie counting is an important part, but knowing what macro-nutrients ratio is just as important. More protein, more fat, more fiber, less carbs will help that a lot. Why is calorie tracking still so important? because fat takes forever to metabolize and is denser than carbs, so (a) You will need to break the psychological programming of expecting food to provide instant fuel, fat will take an hour(ish) to energize you; if you just are "still hungry" and eat more in 30 minutes you're losing the battle. (b) Most of us are used to eating a volume of food that equates to the calories we want from carbs. Eating that much in fat will obviously not help weight loss goals, so when eating fat dense foods we must eat much smaller portions. There are really two separate feedback loops we use to feel sated. Fat is good
- danbruc 12y ago
  [...] psychological programming of expecting food to provide instant fuel [...] Is this a real thing? Eating makes me less hungry but not more energetic no matter what I eat.
  - jasallen 12y ago
    I think maybe I wasn't clear. Normally when you eat, you expect to not feel hungry any more. In particular, if you are targeting a calorie deficit or weight loss you look forward to that "joy of food" sensation, a big part of which is the glucose that absorbs almost instantly and raises your blood sugar, and more of which absorbs over time beginning immediately. If you are on a low carb meal you will miss that feeling entirely. You won't feel from fat (though you will if you have plenty of protein and fibe) and you won't have the blood pressure spike that most of us associate with "food good" (note I don't mean the extreme spike you would get from eating pure sugar necessarily, just any higher than baseline peaking). So the psychological programming is getting used to not expecting that spike (and possibly that 'full' feeling), and still feeling you sated your self.
msandford 12y ago
Our bodies have what the engineer in me might call a "control system" for blood sugar. When you're talking about control systems in engineering you look at the step response and that's what tells you everything you need to know. You have a "plant" which is the thing you're controlling and you have the "control system" which is the thing that provides negative feedback and thus controls the "plant". If the control system responds faster than the plant you've got a decent shot at keeping things under control and your system is said to be critically damped or overdamped. Both of these are pretty acceptable solutions for process control. If your system doesn't respond fast enough, it's said to be underdamped and shit is real bad. We're talking the kind of runaway shit that you see in the Tacoma Narrows bridge video. Here's a nice picture of various control systems: http://en.wikipedia.org/wiki/File:Second_order_transfer_function.svg http://en.wikipedia.org/wiki/File:Second_order_transfer_func... Our bodies have a control system for hunger, I'm sure of that. But we don't get to choose how fast that control system reacts; that's fixed. For a lot of foods, our control system responds faster than our blood sugar and things are fine. But some foods can cause our blood sugar to go up faster than we can store it or otherwise react to it. Then eventually enough insulin gets dumped into the blood stream that blood sugar starts to crash. So then you get really hungry and start eating again. The more you eat large amounts of easily digestible sugars, the further you go from the critical damping of (zeta = 1) to horrifically underdamped (zeta = 0). I wonder when the engineers and the scientists are going to get together and hammer this stuff out formally.

by Udo 12y ago

SatoshiPacioli 12y ago

There's a wealth of information on ketogenic (low to no carb) diets: http://www.reddit.com/r/keto http://www.reddit.com/r/keto Everyone serious about this understands that carbs are the problem.

ajcarpy2005 12y ago
Or for underweight people, part of the solution.
steeve 12y ago
I came here to post this. I wish people knew more about keto.
mistermann 12y ago
Also, most people have no idea the type and variety of foods you can continue to eat while on an extreme low carb diet: http://www.reddit.com/r/ketorecipes/top/ http://www.reddit.com/r/ketorecipes/top/
jasallen 12y ago
ultra-low to no carb on a daily basis has severe issues with it as well. Things like carb-cycling, or low (but not ultra-low) attempt to address those issues. The main points being (1) brain needs glucose, can't fuel any other way (2) glucose is needed for maximum muscle response so if you are fit/athletic in any way you can be short-changing your performance if you have no glycogen stores to tap for "burst fuel"
- hollerith 12y ago
  >brain needs glucose, can't fuel any other way Not so: the brain can be fueled by ketone bodies, which the liver can create from fat. P.S. I agree with your larger point that avoiding all carbs for many days at a time should only be done by people who have informed themselves of the risks (acidosis and kidney stones).
  - mixmastamyk 12y ago
    What did humans do before large numbers of carbs were widely available? Die of kidney stones? Or perhaps this is because modern people have become accustomed to them being available?
    - merrua 12y ago
      There is carbs in vegetables. Beans too. Just not as much in most of them as grains.
- sgt101 12y ago
  If you are "tapping for burst fuel" why are you worrying about your diet (apart from the sensible am I having good things enough worry...) Surely these diets are aimed at people who need to loose >10% of body weight ?
stinos 12y ago
Care to also post links to scientific evidence next to the reddit? Sure it has information, but from a quick glance it's information without much science/proof to back it up, from people who are already convinced. I think way more is needed to convince the rather critical spirits on HN :)
- desigooner 12y ago
  Lyle McDonald's e-book on Ketogenic Diet is probably the best thing I've ever read. It's well referenced and pretty comprehensive. http://www.bodyrecomposition.com/the-ketogenic-diet http://www.bodyrecomposition.com/the-ketogenic-diet
- Nimi 12y ago
  AFAIK, there are several experimental results supporting low carb diets, but all are refutable, as in someone can always come up with a counter-argument. Robert Lustig and his "Sugar: The Bitter Truth" lecture (available on youtube) is probably currently the best-supported argument. There's an initiative called the "Nutrition Science Initiative" (nusi.org) that apparently attempts to put an end to the debate with irrefutable research, which will finally convince everyone one way or the other. They seem to be still in the early stages.

NIL8 12y ago

Very well said. The consequences would be immense if we could override even one of these triggers.

robert_tweed 12y ago

I'm not sure I agree that this article falls short and does the popular simplification thing. It's the first widely accessible article I've seen that clearly refutes (with data and a citation) the oft-repeated assertion that "a calorie is a calorie". Because the science is still incomplete, the article unsurprisingly ends on a "more research is needed" note, but I completely agree with that! While your point about fat cells, ghrelin and leptin has some factual basis, precisely how these hormones affect eating patterns and are themselves affected by bodyfat, carbohydrate intake and insulin resistance, are among the things that need more carefully controlled studies. I'd also like to see more science into the effects of intermittent fasting. There is IIRC only one actual study on this, far from enough to back up all the various protocols and broscience articles on how "fasting is good for you". Anecdotally, it seems to be very effective for some people but I don't think we yet have a very good understanding of why that is, or indeed whether it is even true under controlled conditions. I personally suspect that carb restriction and intermittent fasting both have very similar effects on this group of 3 hormones, while sugar has basically the opposite effect. What's lacking however is clear scientific evidence of this.

jasallen 12y ago

I really did enjoy this article. I don't think there is anything new here, but it's presented in a very "mass media friendly" way, which is important for finally defeating the "just eat less" mentality. Of course, it is still calorie in, calorie out, but we need to understand what effects metabolic changes in our body if we want to understand what calories are going out. Furthermore, quality of life generally indicates most people don't want to shut their metabolism down even if it did mean weight loss -- we want to be energy using machines that are motivated to "get up and do stuff", so just blindly reducing calories is not the path to that. Calorie counting is an important part, but knowing what macro-nutrients ratio is just as important. More protein, more fat, more fiber, less carbs will help that a lot. Why is calorie tracking still so important? because fat takes forever to metabolize and is denser than carbs, so (a) You will need to break the psychological programming of expecting food to provide instant fuel, fat will take an hour(ish) to energize you; if you just are "still hungry" and eat more in 30 minutes you're losing the battle. (b) Most of us are used to eating a volume of food that equates to the calories we want from carbs. Eating that much in fat will obviously not help weight loss goals, so when eating fat dense foods we must eat much smaller portions. There are really two separate feedback loops we use to feel sated. Fat is good

danbruc 12y ago
[...] psychological programming of expecting food to provide instant fuel [...] Is this a real thing? Eating makes me less hungry but not more energetic no matter what I eat.
- jasallen 12y ago
  I think maybe I wasn't clear. Normally when you eat, you expect to not feel hungry any more. In particular, if you are targeting a calorie deficit or weight loss you look forward to that "joy of food" sensation, a big part of which is the glucose that absorbs almost instantly and raises your blood sugar, and more of which absorbs over time beginning immediately. If you are on a low carb meal you will miss that feeling entirely. You won't feel from fat (though you will if you have plenty of protein and fibe) and you won't have the blood pressure spike that most of us associate with "food good" (note I don't mean the extreme spike you would get from eating pure sugar necessarily, just any higher than baseline peaking). So the psychological programming is getting used to not expecting that spike (and possibly that 'full' feeling), and still feeling you sated your self.

msandford 12y ago

Our bodies have what the engineer in me might call a "control system" for blood sugar. When you're talking about control systems in engineering you look at the step response and that's what tells you everything you need to know. You have a "plant" which is the thing you're controlling and you have the "control system" which is the thing that provides negative feedback and thus controls the "plant". If the control system responds faster than the plant you've got a decent shot at keeping things under control and your system is said to be critically damped or overdamped. Both of these are pretty acceptable solutions for process control. If your system doesn't respond fast enough, it's said to be underdamped and shit is real bad. We're talking the kind of runaway shit that you see in the Tacoma Narrows bridge video. Here's a nice picture of various control systems: http://en.wikipedia.org/wiki/File:Second_order_transfer_function.svg http://en.wikipedia.org/wiki/File:Second_order_transfer_func... Our bodies have a control system for hunger, I'm sure of that. But we don't get to choose how fast that control system reacts; that's fixed. For a lot of foods, our control system responds faster than our blood sugar and things are fine. But some foods can cause our blood sugar to go up faster than we can store it or otherwise react to it. Then eventually enough insulin gets dumped into the blood stream that blood sugar starts to crash. So then you get really hungry and start eating again. The more you eat large amounts of easily digestible sugars, the further you go from the critical damping of (zeta = 1) to horrifically underdamped (zeta = 0). I wonder when the engineers and the scientists are going to get together and hammer this stuff out formally.