When somebody loses weight, where does the fat go? • Hacker News Board

Re: When somebody loses weight, where does the fat go?

#61

Post by mikeash » Mon, Nov 27, 2017, 5:32 PM UTC

sillysaurus3 wrote: post #36

mikeash wrote: post #4

For anyone coming straight to the comments looking for an answer to the question: it turns into CO2 (and a bit of water) and you breathe it out. When you realize that you have to breathe out all the weight you lose, I think it gives you a bigger appreciation for how difficult weight loss can be.

It's better for HN to let the reader dig for information. It attracts the curious. https://hn.algolia.com/?query=by:dang%20%22work%20a%20little...

I respectfully disagree. The only reason I didn't use the word "clickbait" is because it's apparently the actual title of a scholarly paper. A lot of the titles that turn up in your search are what I'd call clickbait.

Re: When somebody loses weight, where does the fat go?

#62

Post by tawayway » Mon, Nov 27, 2017, 5:33 PM UTC

IpV8 wrote: post #54

leshow wrote: post #48

Earlier quoted context omitted.

I'd suspect the more exercise you do the more that number moves up, you'd be breathing harder. I'd hesitate to try and put a 'hard limit' on anything like this.

Also take daylight savings into account, you could get an extra hour one day a year. Thats a lot more breaths.

Not sure about you but I keep breathing 24 hours a day.

Re: When somebody loses weight, where does the fat go?

#63

Post by mikeash » Mon, Nov 27, 2017, 5:33 PM UTC

IpV8 wrote: post #54

leshow wrote: post #48

Earlier quoted context omitted.

I'd suspect the more exercise you do the more that number moves up, you'd be breathing harder. I'd hesitate to try and put a 'hard limit' on anything like this.

Also take daylight savings into account, you could get an extra hour one day a year. Thats a lot more breaths.

Supercharge your weight loss by running west.

Re: When somebody loses weight, where does the fat go?

#64

Post by arikrak » Mon, Nov 27, 2017, 5:33 PM UTC

adekok wrote: post #38

mikeash wrote: post #4

For anyone coming straight to the comments looking for an answer to the question: it turns into CO2 (and a bit of water) and you breathe it out. When you realize that you have to breathe out all the weight you lose, I think it gives you a bigger appreciation for how difficult weight loss can be.

2 pounds a day. That's how much CO2 you breath out, and the hard limit for weight loss. You can lose more than that, (see boxers before a weigh-in), but that's all water loss, and is temporary. And, with a strong likelihood of death.

But you also breathe in co2 with every breath so would need to subtract that..

Re: When somebody loses weight, where does the fat go?

#65

Post by k__ » Mon, Nov 27, 2017, 5:33 PM UTC

Cd00d wrote: post #41

k__ wrote: post #27

Earlier quoted context omitted.

Hehe, true. I once saw a documentary about "big animals" in the past. Like, why did we have giant spiders and insects while they have a rather simple respiratory system that doesn't scale very well. Because: trees! Somehow plants managed to create wood, which bound the C from CO2, but the rest of the biosphere didn't know what to make of the wood. So there were more and more trees and more and more C got removed from…

I thought ants were what made short work of the wood. Something about formic acid? Do you know more - I need to reset my ignorance.

No sorry.

Maybe it was both? The documentary just told about the fungi.

Re: When somebody loses weight, where does the fat go?

#66

Post by jasamer » Mon, Nov 27, 2017, 5:34 PM UTC

corpMaverick wrote: post #33

I am confused by this... > We suspect this misconception is caused by the “energy in/energy out” mantra and the focus on energy production in university biochemistry courses. I understand from the article that chemistry (Which I can't understand) tells you that it is converted on CO2. But still. Clearly I can move because I have energy that I acquire from food. How is this wrong ?

It is not wrong. It just doesn't tell you anything about where the mass goes.

Re: When somebody loses weight, where does the fat go?

#67

Post by SomeStupidPoint » Mon, Nov 27, 2017, 5:34 PM UTC

StevePerkins wrote: post #37

Zanta wrote: post #12

Earlier quoted context omitted.

From the paper "Replacing one hour of rest with exercise that raises the metabolic rate to seven times that of resting by, for example, jogging, removes an additional 39 g of carbon from the body, raising the total by about 20% to 240 g. For comparison, a single 100 g muffin represents about 20% of an average person’s total daily energy requirement. Physical activity as a weight loss strategy is, therefore, easily fo…

I can't help but groan at some of the "obvious" health and weight loss platitudes that get smugly thrown around. " Calories in, calories out! " " You can't outrun a bad diet! " " Weight is lost in the kitchen! " Sure, things ultimately boil down to intake-vs-expenditure. However, it IS more complicated than that in practice . As software developers, we complain when management makes decisions based on inadequate or p…

The most important role of exercise in weightloss is hormone regulation, not the calories burned. (As you correctly point out.)

Being less stressed and routinely expending large amounts of energy simply causes your body to run differently (because of the hormones produced and burned off), which in turn changes how it processes food and fat stores, what it craves, etc.

I think proper hormone regulation is far more sustainable than the calorie restrictions necessary to offset out-of-whack hormones.

Re: When somebody loses weight, where does the fat go?

#68

Post by badestrand » Mon, Nov 27, 2017, 5:35 PM UTC

adekok wrote: post #38

mikeash wrote: post #4

For anyone coming straight to the comments looking for an answer to the question: it turns into CO2 (and a bit of water) and you breathe it out. When you realize that you have to breathe out all the weight you lose, I think it gives you a bigger appreciation for how difficult weight loss can be.

2 pounds a day. That's how much CO2 you breath out, and the hard limit for weight loss. You can lose more than that, (see boxers before a weigh-in), but that's all water loss, and is temporary. And, with a strong likelihood of death.

Well, but you also breath in the O2 first, I think the C just binds to that. C and O weigh similar amounts so it is just 1/3 of the 2 pounds. But you have to count the water loss as well, it is part of fat cells.

How many calories can you max burn per day, around 8000? That would be ~1.1kg of fat loss at 7 kcal per g fat. At a normal day of not eating it is ~300g afaik (2100 kcal at 7kcal/g).

Re: When somebody loses weight, where does the fat go?

#69

Post by naravara » Mon, Nov 27, 2017, 5:35 PM UTC

StevePerkins wrote: post #37

Zanta wrote: post #12

Earlier quoted context omitted.

From the paper "Replacing one hour of rest with exercise that raises the metabolic rate to seven times that of resting by, for example, jogging, removes an additional 39 g of carbon from the body, raising the total by about 20% to 240 g. For comparison, a single 100 g muffin represents about 20% of an average person’s total daily energy requirement. Physical activity as a weight loss strategy is, therefore, easily fo…

I can't help but groan at some of the "obvious" health and weight loss platitudes that get smugly thrown around. " Calories in, calories out! " " You can't outrun a bad diet! " " Weight is lost in the kitchen! " Sure, things ultimately boil down to intake-vs-expenditure. However, it IS more complicated than that in practice . As software developers, we complain when management makes decisions based on inadequate or p…

>During times when I've been 100% sedentary for long periods, I experience overwhelming cravings for sugar and crappy foods.

This is very much a YMMV deal. I am like you in that when I train a lot my appetites for food become healthier leading me to crave more fiber and protein.

My wife, however, is the exact opposite. When she's sedentary she's fine eating whatever. When she's active and training she starts craving junk food and snacks which she has learned to use as a coping mechanism for stress.

I suspect this depends a lot about how you're socialized around eating. She grew up on processed food and her family used sweets and junk food as a rewards when she did well at things. In contrast, my mother regularly cooked from scratch and we only ever ate those "dopamine-hit" foods and snacks on special occasions so in my mind, those are more tied to times of year and social context rather than personal reward or fulfillment.

Re: When somebody loses weight, where does the fat go?

#70

Post by gwright » Mon, Nov 27, 2017, 5:35 PM UTC

wyufro wrote: post #46

corpMaverick wrote: post #33

I am confused by this... > We suspect this misconception is caused by the “energy in/energy out” mantra and the focus on energy production in university biochemistry courses. I understand from the article that chemistry (Which I can't understand) tells you that it is converted on CO2. But still. Clearly I can move because I have energy that I acquire from food. How is this wrong ?

Their point, which I agree is fairly unclear, is that the fat is not converted to energy, it's converted to CO₂ and water. That conversion releases energy, which you then use to move, but the total mass of the process is constant (conserved).

Just to add a bit of clarification, the excess energy part of the equation is coming from the energy stored in the chemical bonds of the original molecules.

The chemical energy of the original molecules is more than the chemical energy of the resulting molecules leaving some energy to do work and to generate heat.