I doubt very much that adding muscle to an underweight person would decrease that person's life expectancy. Probably it would improve it (the health benefits of exercise are well known). Either way, it would improve his quality of life.
And, just to rule out any suspicion of bias, know that I have a job where I’m constantly lifting weight, I have my own strength exercise regime outside work, I drink protein shakes, and I eat quite a lot for my frame.
http://en.wikipedia.org/wiki/Calorie_restriction
But I don't subscribe to the "live long an weak" mentality. I believe that your body is healthier and more capable when well nourished and physically strong. I'm 6'2" 190lbs and continually trying to gain muscle mass.
Nothing proven about it.
In mice anyway.
Not exactly. The calorie restricted mice do live longer unless they get an infection or some other unexpected source of stress, then they die at much grater rates. It is as if they have no reserves.
In humans calorie restriction is absolutely and utterly unproven.
Humans and mice are very different. They are tiny short lived animals, and we are large long lived animals. That is why a lot of the cancer cures you hear about in mice don't work in humans. Because often we already are born with them. There are known tumor suppressing genes, humans have more copies of them than mice, elephants have even more.
This is why it is not reasonable to assume that simple hacks like calorie restriction, which work in mice... sort of, will also work in humans.
A health diet and exercise on the other hand, have been proven to work in humans.
It does. Calorie Restriction is pretty much the only proven way to extend life and slow down the aging process.
The only source for this I've seen so far is the wikipedia page and according to it: There are ongoing studies on whether CR works in primates.
So unless you are a yeast or a fish, it is not proven.
Exercise and a healthy diet on the hand are proven.
(this is all just pure speculation, I have never looked into any of the science regarding calorie restriction)
This has not been proven for humans AFAIK.
The one proven thing you can do to live longer is to not die.
Risk prevention / avoidance is a large part of this, but that includes a lot other than bodyweight. Seat belts, condoms, not smoking, little or no alcohol/drugs, pollution.
Several long term athlete studies show longevity, and quality of life benefits, to exercise (Stanford runners study, Scandinavian olympian study). And the specific mechanism of calorie restriction, telomere repair, is shown in both cardio and strength training.
Not true. Stronger people are less likely to die. Strength reduces your risk of death from all causes - and cancer in particular.
"[The inverse relationship between] muscular strength and death from all causes and cancer persisted after further adjustment for cardiorespiratory fitness; however, the association between muscular strength and death from cardiovascular disease was attenuated after further adjustment for cardiorespiratory fitness."
Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453303/
This is basically a reference point to support the opinion that was stated here: BMI is not the only thing that matters.
Take a look at the two numbers circled in red. The one on the left is the lowest-mortality BMI not adjusting for fat mass or fat-free mass: a reasonably high 27.4. The one on the right is the lowest-mortality BMI adjusting for fat mass and fat-free mass: a much lower 21.6.
I know this may sound confusing, but due to possible statistical distortions this does not mean that you should try to bring your BMI to 21.6 if you want to reduce your risk of dying. What this means is that fat mass and fat-free mass matter.
Anything under 18.5 is considered "underweight", just as anything over 25 is considered "overweight". 17.6 is only off by .9 points. He's less off the charts than someone 6'0 and 195lbs (BMI of 26.4)
Not true. If you go by the raw numbers, your BMI of 17.6 puts you at the same death risk as someone who has a BMI around 30 (which is borderline obese): http://ars.els-cdn.com/content/image/1-s2.0-S014067360960318...
Article: http://www.sciencedirect.com/science/article/pii/S0140673609...
Both higher than typical BMI and lower BMI are associated with higher mortality risk.
I don't think anyone knows which direction the causality goes ( and that is true for a lot of things, I'm think the direction of causality is unknown for a lot of these articles that say "standing is better" or "people who walk more live longer").
Moreover, your study recruited people at age 46 (mean) and followed them through their death. Meaning, a whole lot of people got older, got sick, subsequently lost weight and died. Unless proper adjustments were made, the low BMI-high mortality connection is rather unproven.
For a similar example, see http://onlinelibrary.wiley.com/doi/10.3322/canjclin.55.5.268...:
The main concern regarding the newer CDC analysis is that it did not adequately account for weight loss from serious illnesses such as cancer and heart disease. Including such individuals in the analysis created the false appearance that being overweight protected against death during the follow up.
and
The newest CDC analysis also failed to account adequately for the effect of smoking on weight. Smokers tend to be a little lighter than nonsmokers, although the negative health impact of smoking far outweighs that of a few extra pounds. As a result, the Flegal study underestimated the risks from obesity and overestimated the risks of leanness.
Regardless, I don't think we are on different pages since you acknowledged that no one really knows which direction the causality goes.
Here's what helped -- about 3 years ago I got into squats and dead-lifting. I got them up to 1.5x and 2x body weight, respectively. I didn't gain a whole lot of weight, but my core strength increased tremendously.
Maintaining good posture requires some (~10-30%) flexion of the core/abdominals at all times while sitting. Now, after learning proper form of squats and deadlifts, my body goes into proper sitting form without even thinking.
Back pain is completely gone. squats and dlifts -- highly recommended!
tldr-its not about weight, its about strength
To anyone reading, you don't have to do more than the big three — squats, dead lift and bench press — to build a strong core and ameliorate most RSI issues.
Regular cardio fitness and 10-minute work breaks are good, but can only take you so far. Being stationed at a computer for extended periods of time requires having a proper muscular frame to support your bones.
Why do lats get no love?
I'll grant that the vertical pull isn't commonly encountered (swimmers excepted) unless you're climbing trees to escape lions/tigers/bears, and I do a fair bit of horizontal pulling exercises as well (open a door, lift something toward you, row a boat).
Focusing on pressing without balance pulling tends toward imbalance IMO/IME.
Since I switched to very basic body weight strength training nearly 2 years ago, problems I thought I would have until I died vanished. Nothing I ate or drank, no amount of aerobic exercises did anything to address those issues.
You should not be developing back pain from standing. Everything else should be getting sore. Back pain, that I've seen, generally occurs from people who either slouch forward at work, have major stress issues, or have some type of actual injury.
It's key to your complaint of discomfort standing up, and it's key to avoiding back or knee problems long-term.
Among other things, gaining good weight (I used to fluctuate between 135-140) has clarified my mind, improved the strength of my heart, and a small host of other nice little upsides. I'm not even to my target weight yet, either.
Remember, just because someone with a BMI of 23 has better health prospects than a BMI of 27, doesn't mean a BMI of 3 is even better.
6' and 130 is very underweight - you don't have to look like a body builder, but your body does need some muscle to function properly. And 130 isn't enough.
Since my weight tumbled to 145 lbs, I noticed a huge difference in my physical well being, especially in sedentary positions. My posture worsened, my back constantly ached, and I started to suffer from RSI. I've been using the same chair all the while, a Herman Miller Mirra.
So, from my experience, weight and muscle mass was a primary determinant of my sedentary well being. Believe me, I was putting a lot less stress on my spine when I was doing 48 pullups in a workout, vs 8 now. I'm slowly working my way back up, and the back pain from sitting has lessened.
Personally, I find working on a sofa with a laptop to be ideal.