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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?

#81

Post by Blackthorn »

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…

Those platitudes are also, well... Wrong. My favorite example:

> "Calories in, calories out!"

Well, sure, but those calories on the label are calculated by burning the components in a machine and measuring the heat output. The human body isn't going to convert the input food at 100%. That percent is going to depend on a lot of factors!

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

#82

Post by mikeash »

maxerickson wrote: post #18
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.

How much weight does a typical person breath out in a day though? (if you figure ~2000 calories worth, it doesn't seem like the breathing weight out is so much the issue...)

According to the article, a typical person will breathe out about 200 grams of carbon per day. (The oxygen in the CO2 comes from oxygen you breathe in, so doesn't contribute to any net weight change.)

A pound of fat is about 3500 calories, and typical sedentary metabolic rate is about 2000 calories per day, so you'd expect to lose about 0.57lbs ~= 260 grams per day if you didn't eat. The article says that CO2 makes up 84% of weight lost (the rest is water), so that fits fairly closely to the 200 grams/day of CO2 breathed out.

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

#83

Post by jaredsohn »

arkh wrote: post #13
JoeAltmaier wrote: post #7

Earlier quoted context omitted.

Exercise makes more sense! Breathing hard == losing weight!

It's easier to eat less calories than exercise.

The insight that I found to be more helpful is that if you want to count calorie losses from exercise as weight loss, you at least need to make sure that you aren't consuming more extra calories than what you burned from exercise.

It can be hard to do this if you don't have awareness over what you typically eat.

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

#84

Post by bluGill »

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).

That release of energy does result in mass loss. e=mc^2 as everybody knows, without understanding. However the energy is fairly small, and c is already extremely large before you square it. Over an entire lifetime the mass loss is still insignificant.

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

#85

Post by jedrek »

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…

I think you're misreading the function of those slogans. First off, they're hardly "obvious" when you account for the overwhelming FUD around nutrition anybody who's tried to lose weight. And you get it from everybody: your Mom, magazines, movies, the news, pop sci articles, the government, etc.

But more importantly, those things are TRUE. Anybody with significant weight to lose will not be able to out-exercise a bad diet. What fat people hear a lot more often is, "oh, you gotta hit the gym". Hitting the gym is great if you're 15 lb overweight, but at 50 or 100 it's all but useless.

> exercise tends to ramp up your metabolism for hours after each exercise session.

Yep. If you spin hard for 45 minutes you get an extra 170kcal through the rest of the day. That is... 2 fun sized Snicker bars, 19 grams of butter, or 17 Pringles chips.

Caloric intake is the absolute key to weight loss. Everything else is complementary. Telling people who are more than a few pounds overweight to hit the gym as the base of their weight loss strategy is complete un-based in science and almost always self defeating.

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

#86

Post by SAI_Peregrinus »

arikrak wrote: post #58
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.

Meanwhile the reverse happens when a tree builds itself by pulling out carbon from the co2 in the air

Trees (and other plants) are almost entirely air and water. Very little soil gets incorporated, and almost all of that is trace minerals dissolved in the water.

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

#87

Post by yodon »

At the risk of crossing the streams here... “wait! HN must be listening to the Microphone on my phone because I talked with my son about this exact topic 36 hours ago and now it’s in my HN feed!”

Yes, that’s a joke, but it’s also a completely factual statement (except for the Microphone thing) and a good reminder that with enough page views even extremely low probability events will happen with great frequency and predictability to someone in your audience (you just can’t predict to whom they will happen)

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

#88

Post by DCoder »

yetihehe wrote: post #47
arkh wrote: post #13

Earlier quoted context omitted.

It's easier to eat less calories than exercise.

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.

I tried it - I lost nearly 25% my weight (down from 132 kg to 101 kg) over this year by eating less and walking on foot a lot more. Eating less is certainly having a lesser effect than it did at first, but I'm still losing weight bit by bit.

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

#89

Post by deadmetheny »

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…

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 their heads around that actually shows results (provided they are actually counting properly).

A couple years after deciding that it's time to get serious about taking care of my body and I'm very close to reaching a healthy weight, and additionally have become reasonably strong due to a weight training regimen. But I wouldn't be here if I hadn't seen the results of calorie counting and taken the next step after the benefits of that started slowing down.

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

#90

Post by rubidium »

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.

"Strong likelihood" only in cases of extreme dehydration. Many wrestlers/ boxers will drop >5 lbs in one day with no longer term impact. The majority of that being water weight they gain right back again.
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