What I learned about weight loss from spending a day inside a metabolic chamber

W

WillowJ

Senior Member (Voting Rights)
A healthy control describes the NIH metabolic chamber which is also being used in the ME study.

https://www.vox.com/2018/9/4/17486110/metabolism-diet-fast-weight-loss?

There are three main ways the body uses calories. There’s the energy needed to keep our hearts, brains, and every cell of our body working, known as the basal metabolism. There’s the energy used to break down food, known as the thermic effect of food. And there’s the energy burned off during physical activity — like walking around, fidgeting, or exercising.

The basal metabolic rate accounts for the largest amount of the total calories a person burns each day (65 to 80 percent for most adults). Physical activity, on the other hand, accounts for a much smaller portion — 10 to 30 percent for most people — despite what many people believe. And digesting food accounts for about 10 percent.
Click to expand...
 
There are three main ways the body uses calories. There’s the energy needed to keep our hearts, brains, and every cell of our body working, known as the basal metabolism.
....
The basal metabolic rate accounts for the largest amount of the total calories a person burns each day (65 to 80 percent for most adults).
Click to expand...
Wow, I didn't realise it was that high. I think this is an important fact that should be emphasized more in discussions about ME, as it shows that, for seriously affected patients, it's far easier to go over their exertion level than is typically appreciated.
 
Yes, most of our energy goes to just staying alive. Its important to realise those stats do not cover extremes like endurance athletes, or the other side like extreme arctic conditions. Athletes can spend more from activity, while extreme cold weather raises the need for energy to just survive.

I have said for some years that we can probably test the bedbound with a metabolic test. Nobody has done so that I am aware of. I had my first metabolic test in 1993. I came out low, but I don't have any numbers.
 
I actually think this analysis is wrong, or at least misleading. I am pretty sure the thermic effect of food is part of the basal metabolic rate, not an extra.

And exercise can be a large proportion of calorie usage. When Ranulph Fiennes and Mike Stroud tried to walk to the North Pole they had to drag their food behind them. They failed because it turned out they were using 7-8,000 calories a day instead of the basic 1,500. People doing really heavy jobs or sports training can easily use 3,000.

I don't know whether calorie usage is of any relevance to the problems in ME. We do not yet have evidence for a problem with calorie usage as far as I am aware.
 
I think the figure, whether it is precisely accurate or not, is useful in illustrating that for anybody just to function for 24 hours takes far more 'effort' than is normally appreciated by most of the population, because it, typically, happens automatically and without perceived effort.

Part of the difficulty in telling the story of PwME is getting healthy people to appreciate that thinking, talking, seeing, digesting etc etc can potentially add up to too much effort for some PwME.
 
Jonathan Edwards said:
And exercise can be a large proportion of calorie usage.
Click to expand...

I think what is interesting is that people’s perception of exercise has changed. Most people in the comfy western rich nations would think 20 mins in The gym 3 times a week is hard exercise. Compare that to a farm laborourer from before the mechanisation of farming (or indeed now in many poorer countries) and this begins to look a bit pathetic. I can well believe the figures quoted here, but only based on sedentary lifestyle of a select number of countries, not as a reflection of the human bodies capacity.

It makes you wonder where and when the 2500 calorie guidance for the “average man” came from?
 
Apparently, a healthy adult creates 50 to 70 billion cells per day just to replace those lost due to normal attrition. If you've ever seen those Inner Life of the Cell videos on youtube, you get some idea of how much activity is going on in a single cell (albeit requiring only minute amounts of energy). I have it on good authority (from my nephew, an evolutionary biologist) that the real speed of events presented in those videos is orders of magnitude faster than what is presented in the animation.
 
Last edited:
Andy said:
just to function for 24 hours takes far more 'effort' than is normally appreciated
Click to expand...

I am not sure that it need involve 'effort'. Using chemical energy does not necessarily equate to effort. The chemical reactions involved are all 'downhill'. In a sense it was the plants that made the effort to create the carbohydrates and fats that we pour down the drain.

I see the point but I am not sure the physiology is right!
 
Jonathan Edwards said:
They failed because it turned out they were using 7-8,000 calories a day instead of the basic 1,500. People doing really heavy jobs or sports training can easily use 3,000.
Click to expand...
Yes, extreme activity and extreme cold both increase energy use. Arctic explorers, on foot, do both. Arctic explorers pre-adapt by going on a high fat diet for a few weeks, then consume huge amounts of fat while exploring. Usually they simultaneously lose not only all the fat they put on but most of the remaining body fat.
 
Thought this might be interesting to compare the effects of activity on calorie needs

https://www.cnpp.usda.gov/sites/def...patterns/EstimatedCalorieNeedsPerDayTable.pdf

Obviously they don’t have a column for indurance athletes or arctic explorers and it looks like this is based on the 2000 calorie advice, which in turn come from a slightly dubious consensus piece from the FDA in the 1960’s (can’t find the exact date)

I think it’s important to though distinguish general health advice (from public health bodies which are always a very averaged number) from the human bodies capacity to burn calories. Basal metabolic rate can vary, but not as much as that from physical exercise that we choose to do.

In turn if we consume more than we need? Portion sizes have increased but this is at the same time as activity levels gave fallen and that’s in my lifetime.

For people with ME there will clearly be a variation in activity levels but I think it’s probably fair to use the sedentary figure as a guide.
 
When I was being tested for metabolic activity in 1993 there were lots of other CFS patients (using Holmes). We were all low. When similar brain scan measures were made, using tagged glucose, our brain metabolic activity was low. This was a consistent finding, but as it was primarily clinical I am not sure it was published.
 
When I was bed bound I'd estimate I ate about 3500 kcal/day - comparable to when I was powerlifting. I became somewhat worryingly skinny compared to my typical build. If I didn't eat every 3 hours I'd become shaky, sweaty and 'adrenaline-y'. It's always struck me as strange that I needed all that fuel just to lie in bed and have even that feel like way too much. I didn't have any digestive problems so I'm sure the calories were being taken in...
I wonder if anybody else's experience is similar. It doesn't seem to be something that comes up a lot.
 
arewenearlythereyet said:
I think what is interesting is that people’s perception of exercise has changed. Most people in the comfy western rich nations would think 20 mins in The gym 3 times a week is hard exercise. Compare that to a farm laborourer from before the mechanisation of farming (or indeed now in many poorer countries) and this begins to look a bit pathetic. I can well believe the figures quoted here, but only based on sedentary lifestyle of a select number of countries, not as a reflection of the human bodies capacity.

It makes you wonder where and when the 2500 calorie guidance for the “average man” came from?
Click to expand...

I remember watching a historical reality TV series quite a few years ago called Frontier House. I found it fascinating.

The series followed three family groups that agreed to live as homesteaders did in the state of Montana on the American frontier in 1883. Each family was expected to establish a homestead and complete the tasks necessary to prepare for the harsh Montana winter. At the end of the series, each family was judged by a panel of experts and historians on their likelihood of survival for each group.
Click to expand...

One of the men lost so much weight in such a very short time that he was convinced that he must be ill. It turned out he wasn't ill. He had lost weight mostly through physical labour. His food intake was considered to be adequate, but of course it didn't include modern food in the quantities he was used to. What I remember from the program is that he was told (I'm paraphrasing) his body now looked like that of a healthy human male and that modern humans had a completely false idea of what constituted normal body size. The man himself had low levels of body fat and was naturally wiry rather than muscular. So he didn't recognise that his thinness was normal and healthy.
 
The background processes of cellular metabolism are called “housekeeping” functions. Most of what occurrs in a cell is thought to be housekeeping. Enzymes cut down on the energy requirements.

It does sometimes take more energy to drive a reaction in reverse.

Typically, protein kinases cleave a phosphate group off an ATP to drive cellular reactions. Also intracellular active transport, and a type of active transport across membranes.

Production of RNA and DNA are done by nucleotides, which cleave a phosphate group releasing energy, similar to ATP (that’s the precise molecule which is the A). This occurs continually.

Cell biology knowledge increases all the time. I am probably out of date by now, but in college I learned things that weren’t known when I was in high school (I did take an extraordinarily long time to make it through college).

Metabolism, with respect to energy usage, comes in two parts.

Cataolism is a destructive process, where the large amount of energy stored in starches, fats, proteins, and even sugars, is broken down in small steps and carefully captuered into high-energy (but less overall energy than fats, etc.) molecules like ATP and NADH.

Anabolism is an constrictive process, where energy stored in molecules like ATP and NADH is used to build some kinds of proteins (not all can be made from other proteins; certain peptides must be supplied by the diet), the particular lipids needed for cell membranes, and so on. (ADP, NAD+, and so on are recycled for use in catabolism.)

And RNA and DNA production, active transport, cellular repair, and so forth, could probably be considered anabolic.

Cellular signaling would fall into both categories, as every state means something to some other cellular bit.
 
“Most people in the comfy western rich nations would think 20 mins in The gym 3 times a week is hard exercise.”

Sure, if the gym has an average age of at least 80 years. I’ve never known a fitness oriented individual who considers 20 minutes anything more than a warm-up, unless it’s 20 minutes of interval training.

Now consider what a triathlete gets into. This is an amateur sport, there’s no televised triathlon league, no college triathlon scholarships, no news coverage, and no glamour. People are not doing this for any outside benefit.

A half length triathlon includes a 50 mile bike ride, a 12 mile run, and about a mile swim.
Some of those half length races are IronMan qualifiers: if you were one of the top few finishers in your class, you are allowed to enter the real IronMan race. That’s a full length triathlon, done in blazing Hawaii sun, less than calm seas and far from flat roads.

Personally I think it should include obstacle climbing, spear throwing and woolly mastodon skinning to be truly authentic, however these additions are unlikely.

20 minutes 3x/week is simply the minimum amount of exercise to hit the aerobic conditioning threshold. It’s a number people hit because they have to. fitness oriented people do more than that with weights alone, not including any running biking swimming climbing cross fitting rowing kayaking or jumping out of airplanes.

I wish I could do even one of those things now.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom