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When somebody loses weight, where does the fat go?

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

#111

Post by sparkzilla »

yetihehe wrote: post #43
Filligree wrote: post #26

Earlier quoted context omitted.

A remarkable fraction of your energy consumption is spent on basic maintenance, and of the rest, far more than you'd think is spent on the brain. Your body is extremely efficient, by engineering standards, but that includes locomotion. Exercise is still a good way to drop in weight, but not simply due to burning up the fat; that could happen anyway. What seems to be happening is that the exercise improves the body's…

> Very few have the willpower to literally starve themselves. Yep, tried this recently with closed loop weight control. After about 8-10kg (from 116kg) lost it's almost impossible to keep on going, you can't control yourself enough to not eat.

I have lost the same amount from about the same weight in the past eight weeks or so, and will have no trouble continuing. The key (for me at least) is to eat a big lunch (around 1000 calories) of whatever you like (today I had burger and fries) and then have a couple of small snacks to a total of 200-300 calories in the evening (I'm eating a Muller corner yoghurt right now). The problem with most diets is that they starve you throughout the day, when the actual problem is habitual snacking. With this method, the most you have to wait is until the next day, when you can eat whatever you like again for lunch. Originally I intended to have a cheat day every 10 days, but I've barely needed them.

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

#112

Post by mikeash »

killjoywashere wrote: post #51
kgabis wrote: post #44

Earlier quoted context omitted.

Also water vapor from you breathing.

The water is the vast majority of the overnight weight loss. pCO2 of 40 mmHg is normal. Resting tidal volume is 500-600 mL, and a breathing rate of 12-14 (officially 10-20, but really, more like 12-14). I'll let someone calculate the mass of CO2 exhaled in 8 hours.

The article claims that 200 grams/day lost as carbon in CO2 is typical. (The oxygen comes from breathing in, so doesn't count for anything.) That implies that the amount lost in eight hours of sleep is somewhat less than 67 grams.

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

#113

Post by JshWright »

SketchySeaBeast wrote: post #80
yetihehe wrote: post #47

Earlier quoted context omitted.

Have you tried it? I did, it's easier only for some time. After you lose about 6-7% of your body weight it's very hard to eat less, your whole behaviour changes.

Is there statistics for this? I recently dropped 20% of my bodyweight, but didn't find that my behaviour changed at all. If anything as the routines set in it became easier.

Generally a sustained weight loss of 10% is considered to be a good target. It's the around the balance point of "real, tangible benefits" and "can actually be accomplished and maintained".

There are absolutely people who are successful at losing (and maintaining) more than that, but they are a pretty small minority.

I don't have sources in front of me, but this is based on many conversations with my sister-in-law, who is just wrapping up her dietetics internship (after completing her undergrad in nutrition). I'm sure I can get some sources from her later in the day if you would be interested.

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

#114

Post by masklinn »

deadmetheny wrote: post #89
StevePerkins wrote: post #37

Earlier quoted context omitted.

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…

For someone who is very badly overweight, cutting calories is still a very good step. My first 100 lbs lost were from doing exactly that. After you get down to merely overweight from terribly obese is when you really need to start caring more about being active and attempting to work exercise into the routine as well. At least from my experience, cutting calories is something that beginners can fairly easily wrap the…

> For someone who is very badly overweight, cutting calories is still a very good step.

It's more or less the only possible step: unless you have an absolutely freaky metabolism, exercise will not be able to mitigate an unhealthy diet until long-term (through increasing basal metabolism by building up muscle mass), and when significantly overweight it's easy to exercise "wrong" and hurt yourself.

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

#115

Post by makapuf »

revelation wrote: post #78
Filligree wrote: post #26

Earlier quoted context omitted.

A remarkable fraction of your energy consumption is spent on basic maintenance, and of the rest, far more than you'd think is spent on the brain. Your body is extremely efficient, by engineering standards, but that includes locomotion. Exercise is still a good way to drop in weight, but not simply due to burning up the fat; that could happen anyway. What seems to be happening is that the exercise improves the body's…

Locomotion is incredibly inefficient, even by engineering standards. An average human exercising is about 22% efficient, that's worse than some ICEs. An electrical engine is >80%.

Electricity is not a source of energy so you have to factor in the efficiency of its production.

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

#116

Post by ultratopo »

k__ wrote: post #27
krallja wrote: post #3

Reminds me of the question “what are trees made of?” (The answer to both questions is “mostly atmospheric CO2.”)

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…

Do you remember the name of the documentary?

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

#117

Post by kaybe »

makapuf wrote: post #107
mikeash wrote: post #63

Earlier quoted context omitted.

Supercharge your weight loss by running west.

But optimize this by not running too close to c (or is it the contrary ? My restrained relativity courses are rusty)

In your reference frame nothing will be different, so it really depends on whether you want to loose weight for yourself or for others.

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

#118

Post by scotty79 »

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.

Thunderf00t had a great take on this showing why excercise is pretty much useless for weight loss.

You exhale same percentage of CO2 no matter how active you are so to burn more fat you have to make yourself breathe faster. You can do that with excercise which, if it's intense, can triple your rate of breathing. But if you do intensly excercise for an hour each day you just burn 26 hours of fat instead 24.

Not much of a difference. You can do much more with skipping some snacks or soda you ingest daily.

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

#119

Post by gnu8 »

dugluak wrote: post #108

a kid asked me a similar question years ago - when you delete a file from the computer, where does it go?

Most computers have a fan that blows the discarded bits out of the CPU. Some of them are built fanless though so the bits just radiate away...

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

#120

Post by TallGuyShort »

badestrand wrote: post #68
adekok wrote: post #38

Earlier quoted context omitted.

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).

I can't tell you how happy it makes me that both methods for estimating weight lost in a day work out to be almost exactly the same.
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