Why does working out reduce fat? page

[dimples]

Sorry if I'm asking a dumb question, but can someone scientifically explain how working out (aerobic & anaerobic) reduces fat?

[magicmerl]

Sorry if this is a dumb answer, but your body requires energy to do work. Your fat is your bodies stored energy reserves.

[Damiana]

It doesn't reduce the number of fat cells, but shrinks them. Whether working out or eating less, the mechanism is similar. Your body uses fat as stored energy, when you use that stored energy, either through exercise or a caloric deficit, you trigger a mechanism inside the existing fat cells that release some fat inside and breaks them down, thus reducing the size of that fat cell.

[JoanieL]

If by anaerobic, you mean resistance/weight training, then it's because it builds muscle. Muscle is more metabolically active than organs, bones, and fat, so you've upped your ability to burn fat.

Aerobic is more general. It can also bump your metabolism up for some time after the actual exercise is over. But mostly it increases your endurance so that you can do harder resistance training and that leads to the above paragraph.

The reason chronic cardio came to be was because someone figured out that aerobic exercise burns a few more calories while you're actually doing it. However, since it doesn't really change your body comp much, it doesn't help you long term.

Anyway, that's my understanding in a very broad way.

[The Scientist]

If by anaerobic, you mean resistance/weight training, then it's because it builds muscle. Muscle is more metabolically active than organs, bones, and fat, so you've upped your ability to burn fat.

Aerobic is more general. It can also bump your metabolism up for some time after the actual exercise is over. But mostly it increases your endurance so that you can do harder resistance training and that leads to the above paragraph.

The reason chronic cardio came to be was because someone figured out that aerobic exercise burns a few more calories while you're actually doing it. However, since it doesn't really change your body comp much, it doesn't help you long term.

Anyway, that's my understanding in a very broad way.

A large amount of this is (very) popular myth. A few important things:

1. Steady state cardio has repeatedly been shown not to contribute to weight loss at all. Also, the increase in metabolism only occurs if people compensate by eating more. If you perform aerobic exercise and try to maintain a caloric deficit, your BMR actually drops.

2. Heavy resistance exercise does lead to meaningful fat loss, but it is not because muscle burns calories. Your body is smart enough to know what its BMR is (assuming you are not metabolically deranged). It is important to remember that adipose mass is regulated by negative feedback control, and every person has a general "set point" that their endocrine system is attempting to maintain. This means that there is something about adding muscle tissue that alters adipose homeostasis. This was shown very elegantly by Izumiya et al. (Fast/Glycolytic muscle fiber growth reduces fat mass and improves metabolic parameters in obese mice) in the 2010 Cell Metabolism paper.

[The Scientist]

Sorry if I'm asking a dumb question, but can someone scientifically explain how working out (aerobic & anaerobic) reduces fat?

To summarize an answer: exercise itself only burns fat if you exercise without compensating by eating more. You can do this for a while, but most people fail long-term because they get so hungry. To really lose weight long-term, you need to make your body accept the fat loss, and this means lower its target adipose mass level. It seems that lifting heavy things is the only type of exercise that will do this, because it is the only way to build muscle tissue. Of course eating a clean diet that keeps you insulin-sensitive is also extremely important.

[Black Timber]

A large amount of this is (very) popular myth. A few important things:

1. Steady state cardio has repeatedly been shown not to contribute to weight loss at all. Also, the increase in metabolism only occurs if people compensate by eating more. If you perform aerobic exercise and try to maintain a caloric deficit, your BMR actually drops.

2. Heavy resistance exercise does lead to meaningful fat loss, but it is not because muscle burns calories. Your body is smart enough to know what its BMR is (assuming you are not metabolically deranged). It is important to remember that adipose mass is regulated by negative feedback control, and every person has a general "set point" that their endocrine system is attempting to maintain. This means that there is something about adding muscle tissue that alters adipose homeostasis. This was shown very elegantly by Izumiya et al. (Fast/Glycolytic muscle fiber growth reduces fat mass and improves metabolic parameters in obese mice) in the 2010 Cell Metabolism paper.

Number 1. just isn't true. When I was in my thirties I was on a local cycling team. I had actually started cycling to get healthy and to lose some weight and it definitely worked. You can't get much more steady state than cycling 50-100 miles. All twenty five of us were very lean. During that time I probably dropped 30 pounds.

[The Scientist]

Number 1. just isn't true. When I was in my thirties I was on a local cycling team. I had actually started cycling to get healthy and to lose some weight and it definitely worked. You can't get much more steady state than cycling 50-100 miles. All twenty five of us were very lean. During that time I probably dropped 30 pounds.

1. Your "evidence" just isn't real data. Did you control for dietary changes that people may have made during their training?

2. I would bet that you did a decent amount of anaerobic work going up hills and probably added some substantial muscle mass to your legs. This is different to plodding along on an elliptical for 30 minutes a day.

[The Rebooted Body]

1. Your "evidence" just isn't real data. Did you control for dietary changes that people may have made during their training?

2. I would bet that you did a decent amount of anaerobic work going up hills and probably added some substantial muscle mass to your legs. This is different to plodding along on an elliptical for 30 minutes a day.

^^ This.

When anyone counters an argument with an anecdote, you can be pretty sure that's as far as their understanding on the topic goes.

[RichMahogany]

To summarize an answer: exercise itself only burns fat if you exercise without compensating by eating more. You can do this for a while, but most people fail long-term because they get so hungry. To really lose weight long-term, you need to make your body accept the fat loss, and this means lower its target adipose mass level. It seems that lifting heavy things is the only type of exercise that will do this, because it is the only way to build muscle tissue. Of course eating a clean diet that keeps you insulin-sensitive is also extremely important.

Stop crushing their CICO dogma with actual facts.