[fasteo]

Muscle mass is a metabolic master regulator:

- It allows fast glucose clearance from blood via both insulin and non-insulin glucose transport.

- It drives bone density by pure mechanical tension. More muscle = stronger bones/tendons to support them. The usual hip fracture/high mortality we see in elderly people follows the loss of muscle mass->loss of bone strength->bone breaks->fall pathway, not the more intuitive fall->bone break.

- It serves as "organ reserve". In case of injury or disease, your muscle mass will literally keep you alive. There are some interesting studies about muscle mass on admission to the ICU and mortality/morbidity. This is the extreme case, but you get the picture.

- Not per-se, but the neurological effort you put in your weight training sessions drive the secretion of Brain-derived neurotrophic factor (BDNF). BDNF improves existing neurons signaling and promotes the creation of new ones. As a side note, I have seen a huge improvement in my - properly diagnosed - ADHD child after putting him in a functional "lift heavy shit" exercise program.

[xiaoma]

Hmm. I don't find this terribly convincing.

Running is well documented in its role in improving bone density: http://healthfully.org/highinterestmedical/id33.html

Unlike weight-lifting there are actual studies showing running promoting neurogenesis (the increase of brain cells) and improving performance: https://www.google.com/webhp?sourceid=chrome-instant&ion=1&e...

Finally, muscle mass is far from enough to be an effective metabolic regulator. While I have yet to meet anyone who runs 100 miles a week and is overweight, it's not uncommon to find that someone who benches 500lbs still carries a gut. I myself have gained a great deal of both fat and muscle since my school years when I was a runner.

I think weight-lifting does some great things depending on one's aesthetic goals, and it's probably the most time efficient way to increase bone density. It's hardly the optimal exercise for general health, though. There are many aspects of health, ranging from neurogenesis to heart health to immune system function to maintaining telomere length that cardio most helps.

[fasteo]

You are implying something that I didn´t mean.

This is not about weight lifting vs running. Anand is already running and I suggested him to add some weight training to gain some lean mass, as his BF level (19%) is a little high, possibly due to the lack of muscle mass.

For the record, I run - or bike - at least twice per week.

[xiaoma]

That doesn't make much sense. As a competitive runner in school, I was under a 5% body fat percentage without really lifting. Now I do lift and I'm at about a 23% body fat percentage (and nearly 3x the arm strength I once had). Runners tend to have a significant lower body fat percentage than lifters, even at a professional level.

More likely is that the OP just isn't doing enough. Running 25 miles a week is enough to bring about significant benefits in health and fitness along with moderate weight control benefits. 25 miles a month is just a waste. Going up from 1-2x per week to 3-4x makes a huge difference.

Most likely is that it's a dietary issue. While living in Asia, I knew many, many non-exercising people at healthy weight levels just because they didn't overeat like Americans tend to. The OP probably doesn't eat like them.

[fasteo]

Uhmm, looking at all the comments to my initial comment, I think this has gone offtrack:

- I am not against running, but I consider weight lifting a necessary addition to it.

- I am not talking about lowering body fat or aesthetics. I am talking about health. A lower body fat is healthier up to a point. Single digit body fat level is just an unhealthy as a 30% body fat level.

- In the same sense, this is not about how much calories muscles burn as this is irrelevant to health. My point is about the role muscle has in maintaining homeostasis in our metabolism.

- My point is/was to help Anand: My sweet spot for body fat level is 13-14%. This is where I feel and perform the best. Anand is at 19% and I believe it is because lack of lean mass; that´s why I recommended him some weight lifting.

[xiaoma]

>A lower body fat is healthier up to a point. Single digit body fat level is just an unhealthy as a 30% body fat level.

[citation needed]

>Anand is at 19% and I believe it is because lack of lean mass; that´s why I recommended him some weight lifting.

My point was that this belief doesn't make sense. Some people who lift and have a lot of muscle mass are lean, but many others aren't. A billion people who don't body-build are leaner than the OP. An objective observation of people (or even countries of people) who are or aren't fat doesn't generate very convincing evidence for the theory that people are fat "because of a lack of lean mass". It's because of their diets.

On the contrary it tends to be exactly those groups most interested in weight training who are the fattest— e.g. Americans and, to a lesser extent, Anglophones in general.

http://www.nationmaster.com/country-info/stats/Health/Obesit...

[tertia]

you were probably under-eating as a runner.

[xiaoma]

Lolwut? Not sure where you came up with that. Actually, I was eating more then than now and was doing well.

[tertia]

"Finally, muscle mass is far from enough to be an effective metabolic regulator. While I have yet to meet anyone who runs 100 miles a week and is overweight, it's not uncommon to find that someone who benches 500lbs still carries a gut. I myself have gained a great deal of both fat and muscle since my school years when I was a runner."

1. Take an equal amount of fat vs muscle: which will burn more calories? Muscle, obviously. 2. People who bench 500lbs are not that common, and those that are are probably power-lifters, not body-builders. There's a big difference. Power-lifters are more apt to gain 'dirty weight' (meaning fat included with the muscle) to help them drive ever-higher PRs.

[xiaoma]

Of course, muscle requires more food to maintain than fat does. I think you missed the point.

What I was saying was that merely building muscle doesn't do much in terms of cutting down body fat. Muscle burns calories, but people with more muscle also tend to eat more calories. This is even true of people who have extraordinary quantities of muscle.

Cardio, on the other hand, only works that way up to a point. People who do a bit of running also tend to compensate by eating more. However, after a certain level of volume, cardio starts to suppress the appetite to about what's needed to maintain the workload. This is probably why I've never seen anyone, including myself, manage to keep the weight on after getting over about 70 miles/week (about the level of an ambitious high school cross-country runner).