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> Again, it all comes back to calories in vs calories out. Which is both true and irrelevant, because the system that governs calories in and calories out is a

by ef4 13y ago

> Again, it all comes back to calories in vs calories out. Which is both true and irrelevant, because the system that governs calories in and calories out is a complex control loop. When it's working correctly, weight is effortlessly maintained within a narrow range thanks to compensating adjustments in appetite and, to a lesser extent, metabolism. When it isn't working right, people try to drive the process with their frontal cortex instead, which only a small fraction of population can actually achieve for any significant length of time. So the most interesting questions in nutrition science are all around what effects satiety and why we have an epidemic of people with broken control loops. Sugar is a very strong suspect in that investigation. And before someone says we aren't evolved for an environment of plenty, and our bodies just hoard every calorie they can get in case of famine -- that's really not it. No mammal simply hoards every calorie it can get without homeostatic feedback. Survival incentivizes balance -- hoarding a calorie means you don't spend that calorie today on something else that would aid your reproductive success. Which is why we (and most animals) have an extremely dynamic system to monitor and maintain appropriate energy stores.

jamesaguilar 13y ago
> Which is both true and irrelevant, because the system that governs calories in and calories out is a complex control loop. When it's working correctly, weight is effortlessly maintained within a narrow range thanks to compensating adjustments in appetite and, to a lesser extent, metabolism. What evidence leads you to believe this? There's no prima facie reason to believe evolution has adapted mammals to a glut of food, since for all but, generously, about the last ten thousand years, it wasn't really a problem that a significant portion of the gene pool faced. It would require some evidence to believe that the body has this capability.
- beachstartup 13y ago
  a bear is a perfect example of an mammal that uses its insulin response during glut times to store fat. 1. gain weight during the summer by eating high sugar, high starch, high calorie foods such as fruit, berries, roots, honey/insects, and as much whole fatty fish as it can get its hands on for a super high calorie kick. it HAS to gain weight in the summer, and does so easily on that diet. 2. during the winter it hibernates and burns nothing but fat, losing the weight and avoiding starving. people can do this too, believe it or not. fasted ketosis is a thing you can sustain for quite a while as long as you drink water. this doens't prove anything in humans, but is an obvious counter-example to no evidence to believe that mammals don't have food glut adaptations. but just for anecdotes' sake, what does an obese human typically eat? exactly the same diet. high sugar (soda/fruit juice), high starch (all junk food), roots (LOTS of potatoes, mostly fried), and extremely high calorie kickers like cheeseburgers and pizza to ensure a calorie surplus.
  - jamesaguilar 13y ago
    Um. Bears don't have a glut in the summer. They eat everything they can and some still die from not getting enough. A glut is when there is so much food that you can eat more than is healthy. You don't see bears passing up salmon saying, nah, I had enough.
    - beachstartup 13y ago
      define:glut in google says "an excessively abundant supply of something." i'm pretty sure if a bear can gain hundreds of pounds in a few months, there's an excessively abundant supply of food. if not, well, there isn't a glut, now is there. and there's soon going to be no more bear, either.
    - burgreblast 13y ago
      > You don't see bears passing up salmon saying, nah, I had enough. I thought it was interesting to learn from Alaskan's that when salmon are plentiful, bears will gut the salmon and just eat those tasty eggs. Who knew? My mental picture had never included them possessing much of a palate. This article suggests they also go for the brains and skin. http://grizzlybearblog.wordpress.com/2010/07/21/grizzly-bear-eating-salmon/ http://grizzlybearblog.wordpress.com/2010/07/21/grizzly-bear...
- bjterry 13y ago
  The !Kung people were a hunter-gatherer tribe in South Africa that persisted with the traditional way of life into the modern era. They had tons of food (the mongongo nut is available year-round in "truly massive quantities") and were still fit by modern standards (even thin), so it's not merely a question of the availability of food. This lends credence to the idea that it isn't merely the quantity of food availability, but its unnatural palatability that makes people overeat. http://ajcn.nutrition.org/content/71/3/665.full?ijkey=f7644b482b3a3375f7ca3c77e4cfe27640bdae83&keytype2=tf_ipsecsha http://ajcn.nutrition.org/content/71/3/665.full?ijkey=f7644b...
- ef4 13y ago
  There is lots of evidence, of several different kinds. At the biochemical level, we actually know a lot about some of the pathways that allow food and body fat composition to govern appetite. See, for example, leptin signaling. At the anthropological level, we have good examples of several different pre-agricultural societies where food was abundant and obesity was rare. At the whole-animal experimental level, researchers have demonstrated in both rats and humans that when you give an animal unlimited access to food, it doesn't gain unlimited weight. It reaches a plateau and then resists further changes up or down from there. Interestingly enough, rats fed a diet of unlimited human junk food reach a much higher plateau than rats fed a diet of unlimited standard rat chow. And finally, we all know people (perhaps even our younger selves) who never consciously worry about what they're eating yet undergo very little fluctuation in weight. Judged from the perspective of a control system designer, getting that kind of stable outcome from wildly varying inputs doesn't just happen by luck. And indeed, experimenters have shown repeatedly that "naturally lean" people experience reduced appetite in the days following a period of overeating. You can even deliberately perturb the system by force-feeding them, and they bounce right back to their long-term weight thanks to reduced appetite and increased metabolism.

by ef4 13y ago

jamesaguilar 13y ago

> Which is both true and irrelevant, because the system that governs calories in and calories out is a complex control loop. When it's working correctly, weight is effortlessly maintained within a narrow range thanks to compensating adjustments in appetite and, to a lesser extent, metabolism. What evidence leads you to believe this? There's no prima facie reason to believe evolution has adapted mammals to a glut of food, since for all but, generously, about the last ten thousand years, it wasn't really a problem that a significant portion of the gene pool faced. It would require some evidence to believe that the body has this capability.

beachstartup 13y ago
a bear is a perfect example of an mammal that uses its insulin response during glut times to store fat. 1. gain weight during the summer by eating high sugar, high starch, high calorie foods such as fruit, berries, roots, honey/insects, and as much whole fatty fish as it can get its hands on for a super high calorie kick. it HAS to gain weight in the summer, and does so easily on that diet. 2. during the winter it hibernates and burns nothing but fat, losing the weight and avoiding starving. people can do this too, believe it or not. fasted ketosis is a thing you can sustain for quite a while as long as you drink water. this doens't prove anything in humans, but is an obvious counter-example to no evidence to believe that mammals don't have food glut adaptations. but just for anecdotes' sake, what does an obese human typically eat? exactly the same diet. high sugar (soda/fruit juice), high starch (all junk food), roots (LOTS of potatoes, mostly fried), and extremely high calorie kickers like cheeseburgers and pizza to ensure a calorie surplus.
- jamesaguilar 13y ago
  Um. Bears don't have a glut in the summer. They eat everything they can and some still die from not getting enough. A glut is when there is so much food that you can eat more than is healthy. You don't see bears passing up salmon saying, nah, I had enough.
  - beachstartup 13y ago
    define:glut in google says "an excessively abundant supply of something." i'm pretty sure if a bear can gain hundreds of pounds in a few months, there's an excessively abundant supply of food. if not, well, there isn't a glut, now is there. and there's soon going to be no more bear, either.
  - burgreblast 13y ago
    > You don't see bears passing up salmon saying, nah, I had enough. I thought it was interesting to learn from Alaskan's that when salmon are plentiful, bears will gut the salmon and just eat those tasty eggs. Who knew? My mental picture had never included them possessing much of a palate. This article suggests they also go for the brains and skin. http://grizzlybearblog.wordpress.com/2010/07/21/grizzly-bear-eating-salmon/ http://grizzlybearblog.wordpress.com/2010/07/21/grizzly-bear...
bjterry 13y ago
The !Kung people were a hunter-gatherer tribe in South Africa that persisted with the traditional way of life into the modern era. They had tons of food (the mongongo nut is available year-round in "truly massive quantities") and were still fit by modern standards (even thin), so it's not merely a question of the availability of food. This lends credence to the idea that it isn't merely the quantity of food availability, but its unnatural palatability that makes people overeat. http://ajcn.nutrition.org/content/71/3/665.full?ijkey=f7644b482b3a3375f7ca3c77e4cfe27640bdae83&keytype2=tf_ipsecsha http://ajcn.nutrition.org/content/71/3/665.full?ijkey=f7644b...
ef4 13y ago
There is lots of evidence, of several different kinds. At the biochemical level, we actually know a lot about some of the pathways that allow food and body fat composition to govern appetite. See, for example, leptin signaling. At the anthropological level, we have good examples of several different pre-agricultural societies where food was abundant and obesity was rare. At the whole-animal experimental level, researchers have demonstrated in both rats and humans that when you give an animal unlimited access to food, it doesn't gain unlimited weight. It reaches a plateau and then resists further changes up or down from there. Interestingly enough, rats fed a diet of unlimited human junk food reach a much higher plateau than rats fed a diet of unlimited standard rat chow. And finally, we all know people (perhaps even our younger selves) who never consciously worry about what they're eating yet undergo very little fluctuation in weight. Judged from the perspective of a control system designer, getting that kind of stable outcome from wildly varying inputs doesn't just happen by luck. And indeed, experimenters have shown repeatedly that "naturally lean" people experience reduced appetite in the days following a period of overeating. You can even deliberately perturb the system by force-feeding them, and they bounce right back to their long-term weight thanks to reduced appetite and increased metabolism.