3 ms·

I think the main issue is just that "efficient" can misleading to dieters. It's not efficiency as in "do more with less," but rather, "do less with less." As y

I think the main issue is just that "efficient" can misleading to dieters. It's not efficiency as in "do more with less," but rather, "do less with less." As your body sheds fat, it no longer needs to expend energy building, preserving, and keeping your fatty tissue warm. JIT energy use instead of lossy battery storage. It doesn't further slow your metabolism beyond what you are genetically predisposed towards, but metabolism does slow (a little bit). Another way to think of this is, when you consume in excess of what you need for healthy living, your body begins consuming additional calories in order to build and support the additional long-term reserves you are creating and maintaining. We have decades of research supporting this notion (as well as common sense). There may also be an aspect of "hibernation" that kicks in when dramatic caloric restriction is suddenly introduced. That is, you are further inclined to be less active as you lose weight quickly. I'm less certain of that, though.

rawoke083600 4y ago
squinting hard enough there are some evolutionary mechanism at play, for example in times of famine(severe calorie restriction), menstruation will stop for female. Pretty sure sperm production also fall for men. So the body has definitely way to sense and adjust in some areas.
rossnordby 4y ago
"Do less with less" is a good way to put it. It can be helpful to look at the extremes- for example, people who are starving can end up with suppressed thyroid function (among other things). This appears to be adaptive; a hypothyroid state will tend to avoid building or sometimes even maintaining metabolically expensive muscle, overwhelming exhaustion will tend to suppress nonvital calorie expenditure, and even fidgeting behaviors can be suppressed. In other words, by reducing burn rate, you starve slower. This is not something you want happening in a well-nourished individual. Beyond making you more likely to die to predation or accidents from severe muscle wasting, it also just feels horrible. There's a reason why people with untreated hypothyroidism (unrelated to starvation) struggle with exercise and weight loss. I've also personally observed some people on... inadvisable extreme crash diets getting some weird bloodwork numbers. Like TSH spiking by a factor of 10- which, unlike the above starvation case which typically suppresses TSH, may imply malnutrition and inability to produce sufficient thyroid hormone. Their empirically derived caloric burn rate dropped by more than 30% over the duration of the diet, and a substantial amount of that was from dramatic muscle wasting. Not exactly ideal!

rawoke083600 4y ago

squinting hard enough there are some evolutionary mechanism at play, for example in times of famine(severe calorie restriction), menstruation will stop for female. Pretty sure sperm production also fall for men. So the body has definitely way to sense and adjust in some areas.

rossnordby 4y ago

"Do less with less" is a good way to put it. It can be helpful to look at the extremes- for example, people who are starving can end up with suppressed thyroid function (among other things). This appears to be adaptive; a hypothyroid state will tend to avoid building or sometimes even maintaining metabolically expensive muscle, overwhelming exhaustion will tend to suppress nonvital calorie expenditure, and even fidgeting behaviors can be suppressed. In other words, by reducing burn rate, you starve slower. This is not something you want happening in a well-nourished individual. Beyond making you more likely to die to predation or accidents from severe muscle wasting, it also just feels horrible. There's a reason why people with untreated hypothyroidism (unrelated to starvation) struggle with exercise and weight loss. I've also personally observed some people on... inadvisable extreme crash diets getting some weird bloodwork numbers. Like TSH spiking by a factor of 10- which, unlike the above starvation case which typically suppresses TSH, may imply malnutrition and inability to produce sufficient thyroid hormone. Their empirically derived caloric burn rate dropped by more than 30% over the duration of the diet, and a substantial amount of that was from dramatic muscle wasting. Not exactly ideal!