Category Archives: 13. Fitness

Sitting Too Long is Bad for You

Sitting Too Long is Bad for You

Reference:   Annals of Internal Medicine Jan 2015

How bad?   This is a big problem. I spend all day sitting. I’m a “knowledge worker”. You know, indoor work, no heavy lifting.   Computer, desk, phone and intellectual work.   Eight hours a day. Sound like you?  (Then I go home and slump over on the lazy boy in front of the TV – at least in winter.)

Ok, these guys took a serious look at the literature and found 47 studies that looked at mortality, hospitalizations, cancer, diabetes, heart disease against the variable “how long you sit”.   They did admit to quite a bit of variability in the studies, and listed that as one draw back. But regardless of physical activity outside of the sedentary time, there was fairly dramatic strong associations with sedentary time and all the list above: heart disease, diabetes, cancer, hospitalizing and just plain not living as long.  It was across all studies.  This is what we call a “Meta-analysis”, combining the data of all pertinent research to answer big, hard questions.

What were the numbers?   Their data shows numbers like a hazard ratio of all cause mortality of 1.24. That basically means you die 24% faster.   Get it? Hazard ratio for heart disease was 1.179.   That’s about 18% more heart disease. No matter how much you go to the gym, exercise outside of work or work out on weekends, you get heart disease 17.9% more just by sitting too much.    Cancer mortality? Also 17%.   Cancer incidence was 13%. Type II diabetes? 91%.   And that may be the key link. Your diabetes risk goes up, meaning your blood sugar goes up and that leads to higher blood fats, inflammation and glycation which are the real cause of heart disease.

The authors did note that the effect was more pronounced in those who spent more time being completely sedentary, but going to the gym for 30 minutes was not protective if you then sat for 8 hours.   There was about a 30% variability in risk between those who didn’t exercise at all with those who did, do it’s not completely accurate to portray this as a complete disqualification of exercise. But it is a risk to sit. In fact, you can put it on a par with smoking. It might be the one other most serious risk to us, besides eating diets of sugar and carbohydrates and getting fat from that. Going to the gym is very noble, it’s just not enough when you erase the benefit by sitting the rest of the day.

What’s not known yet is just how much sitting can we really get away with. The authors suggest that we should aim for a two to three hour reduction.   Maybe you don’t need to do it all at work. How about learning to stand more at home. Use your imagination. Create a hobby at a work bench where you can stand, instead of sit.

WWW. What will work for me. Ok, I’ve been talking about this forever.   I need to get over my putzing around, doing nothing. The data is there and it’s powerful. Neither you nor I can let ourselves sit every day, all day.   Find a way to re-craft your work environment so that you stand part of the day. Make a grease board on your office wall.   Put in a higher counter so that you can stand while your work. Make your phone calls standing.   Express support and admiration for those early adaptors who have already done it. Talk to your office design company!   They’ve got ideas.   But most of all, ask me what I did in my office next time you see me. I’m determined to get over my lazy ass attitude and get a grease board so that I can stand. I draw a lot of pictures on pads of paper. Time to do on the wall, so I’m standing.

 

Pop Quiz

  1. Sitting a lot has the ability to increase your risks for cardiovascular disease, cancer, diabetes, early mortality, more hospitalizations. T or F

Yup

  1. Sitting 8 hours a day may be almost as bad as smoking. T or F

True.

  1. Exercising has some benefit, much of it undone by 8 hours of sitting.

Yes, it appears that the good exercisers do decrease their risk by about 30% over those who never lift a finger. That means their risk is only 70%. That’s still up.

  1. We know how much you need to stop sitting. T or F

Not yet.

  1. Reasonable goal would be to cut down 2-3 hours a day of sitting.

That’s the author’s advice.

 

 

 

Brown Fat, Good Fat

Brown Fat, Good Fat

References:   Seale, Diabetes , van der Lans JCI Images from van der Lans, Cypess NEJM

 

It’s cold.   Wisconsin gets cold but this is extra lousy.   Last winter, it lasted for months.   Yet, my squirrels sit out there on the feeder and look toasty warm. How do they do it?     Brown fat.

Ever heard of brown fat?   You had a lot of it, once. As a newborn, a fair amount of your fat is brown fat.   It is stored in greatest amount between your shoulder blades. But check out the image link above for where PET scans show you to have fat. The amount regresses rapidly as you age, and adult humans don’t have much.   But, we keep ourselves warm all the time.   Squirrels and rodents in general have a lot of it.   They don’t have central heating in their dens.

What is important about brown fat? It has a unique protein in it that takes the energy you might normally convert into your internal gasoline called ATP, and instead makes it into heat.   That’s it. It simply turns on an internal heater that keeps you warmer without shivering. It’s called NST or Non Shivering Thermogenesis. Of course, you would be burning energy but you aren’t actively moving muscle to do it. Instead, you get all the energy turned into heat. The protein is called UnCoupling Protein or UCP-1, if you want jargon.    Regular skeletal muscle doesn’t have UCP. All it can do is shiver.

Now, Cypess in the NEJM reference above did a brilliant study showing that humans have a lot of brown fat. It shows up actively on PET scans, looking for cancer, as little hot spots.   But people who have been kept warm all the time, never need to develop their brown fat and have much, much less of it.

Hmmm. Can you develop your brown fat?   Can you get used to the cold?   Well, aren’t you feeling a bit more used to winter now than you used to be? Remember how cold you were that first day in November when we had the first return of the dreaded polar vortex? Yes, you do get used to the cold. You get acclimatized to it. It is a result of developing your brown fat.   How do we know that?

That what van Der Lans article is about.   He took 17 healthy young adults (23 +/- 3 years) and exposed them to 6 hours a day of temperature of 16 degrees celsius (60o F).     They did that for 10 days, then repeated PET scans on them to measure the change in their brown fat.   Results: a lot more brown fat, less shivering, less feeling cold,   Non-shivering thermogenesis or NST increased from 10% to 17% and their resting metabolic rate increased . Women went from 6.2 to 6.9 MJ/hour of resting metabolic rate.   Men went from 7.6 to 8.5 MJ.   They were acclimatized to the mildly cold temperature.

But did you get that?   You can turn up the rate at which your basal metabolism is cooking along. Could this be a way of losing weight and controlling diabetes? Yes! That’s what Seale’s article is about. As animals get fat with forced feeding experiments, they make more brown fat.   Their bodies are trying not to gain weight by having their NST turned on.   They stay hot all the time as an effort to get rid of their extra calories. Cold may be your friend. You just have to get used to it.

WWW. What will work for me.   Well, I’m out in this miserable cold every day, off and on.   I’ve not been hiking or walking as much as I would like because I don’t want to break an ankle. But I am turning our thermostat down at night.   I wish I could get a PET scan and see how much brown fat I had stored up.

Pop Quiz

  1. Brown fat is what keeps animals warm in winter – that’s how the squirrels are staying alive right now (-8o). T or F

True

  1. Humans have brown fat? T or F

Also true. Especially just as we are born.

  1. Most of our brown fat is between our shoulder blades?   T or F

True, also around our torsos

  1. We can make more brown fat by being exposed to 60o temperature for 10 days.   T or F

True

  1. Brown fat has been proven to help us lose weight? T or F

False. Not proven yet, but very intruiging.

  1. As animals get obese, they make more brown fat? T or F

Also true. And stay warmer – as though they were trying to get rid of the extra fat.