kuan

I understand that some people (diabetics or thyroid problems for instance) may have a hard time metabolizing carbohydrates. I know the feeling of being hungry all the time. I know how easy it is to let things slip because I did it myself, but I want to know one thing.

I just watched a show on Discovery Channel about an 84lb. baby with a genetic disorder. Apparently this baby eats normal and gains weight like crazy. What I want to know is this. It takes a certain amount of energy to move x number of pounds x number of feet. There's an actual caloric requirement to do so. Forget metabolism for a moment. If you have to ride a bike connected to a dynamo to raise 100 grams of water by 20 degress, you have to put out 2000 calories. This is assuming 100 percent efficiency in the system. How can people with metabolic disorders eat 2000 calories a day, do 2000 calories of work, and still gain weight? Can they? If they can doesn't that mean that their bodies are more efficient than the laws of physics?

DannoXYZ 

First, a food calorie is technically a Calorie or a kilocalorie in lab terms. So the daily budget of 2000 Calories is enough to raise 100kg of water by 20 degrees-C. This is more appropriate as far as what a human burns every day and most of this energy is lost through maintaining body heat. During resting non-movement phases, the greedy brain consumes something like 60% of the glucose calories being burnt.

You've mentioned a couple of different disorders that may be present individually or in combinations within the same person. The carbohydrate disorder is known as G6PD deficiency where the enzyme glucose-6-phosphate dehydrogenase is lacking. This is produced by red blood-cells which aids in the metabolism of CHO. The cause of this disorder is actually some other disease which kills red blood cells and triggers a cascading downward spiral because G6PD is also used in protecting red blood cells. The result is excess CHO that's not metabolized and converted to fats, and weight-gain results.

Another disorder is hypothyroidism where insufficient amounts of thyroxine is secreted. This lowers your BMR - basal metabolic rate and you also end up with excess CHO. Which again is converted to fats. With increase body-fat percentage, the body has more insulation and less energy is needed to maintain body-temperature.

In both these cases, excess unmetabolized CHO can also result in diabetes complications as well. One effect of not burning off enough CHO is that you have lowered body-temperatures. The person will have a slightly lower body-temp than normal and will feel cold when everyone else is warm. The lower delta-T with the outside air means they will be shedding less heat to the atmosphere, thus will burn fewer calories to maintain the lower body-heat. The lack of CHO metabolism also gives less energy to the brain and causes continual fatigue, memory loss and general mental lethargy.

Bottom line is the overall daily energy consumption may end up being only 1/3rd to 1/2 of what a normal human burns off. If these people eat as much as a normal human being, they can easily gain 1-2 lbs per week.

kuan

Man I didn't know that the brain consumed so much! That makes more sense now.

How come you know so much Danno, are you some kind of, well I dunno what, medical something or other?

So people who smoke crack and kill most of their braincells should be fatter than normal right?

2manybikes

Maybe the high percentage the brain needs explains why after a long hard effort sometimes you can still ride more miles, but it's hard to think complicated things out.

Sometimes at the end of a super hard century I know I could keep riding, but I could not figure out the tip at a restaurant if my life depended on it. I know it's pretty common.

kuan

Sure explains the dichotomy in HS between jocks and nerds. You can't be both. ;D

OK maybe not... hmmmm.

lws

Danno is right on except for one little nit Perception of temperature is not necessarily linked to one's body temperature. Unless you mean that if your body temperature is low and I put my hand on you, you will feel cold *to me*. Hypothermia comes with a sensation of warmth. Fevers often come with a sensation of cold. Thin women that I know feel quite warm to me, but are more sensitive to temperature. Temperature sensitivity increases with age, independent of age-related metabolic changes.

This isn't really important except that I wouldn't want people to think "gee, I always feel cold, must be that I have a slow metabolism". T'aint neccessarily so.

DannoXYZ 

Yes, it's the actual skin-surface temperature will be lower than normal as measured by outside instruments and observers. This is partly caused by vascular constriction at the extremities to preserve the core organs. You end up with cold hands and feet.

bbattle

People that claim "it's a glandular problem" or "I have big bones" are really eating more than they let on or even know themselves. The next time someone says "I don't know why I gain weight, I don't that much at all", watch them all day and see what they eat. Or get them to write down what they eat and how much of it they ate. It's a real eye opener.

People that go on fad diets, lose some weight, then go off the diet and gain the weight back are training their bodies to be more efficient in storing the food as fat. There are people that gain weight while eating only 1000 calories a day.

By having a daily exercise routine, you train your body to be on "alert" to burn calories and keep the fires at the ready for converting more fat and carbs to energy. The body doesn't pack everything away as fat because it knows it'll be needing energy soon and that's why active people are more alert, cheerful, think better, and in general, have that annoying healthy glow and upbeat attitude that really irritates the sloths who are still trying to wake up with that third cup of coffee.

danch

Then there are the active people who are still trying to wake up with that third cup of coffee! <raises hand>

bbattle

Get old like me and you'll be waking the chickens up.


I'm so glad I got my bike. It's exercise that I really enjoy and I don't have to make myself do it. My wife thinks I'm obsessed; I haven't told her about OCP. I had been slowly improving my diet before the bike; no more fast food, no colas, cut out chips except for these pita bread chips, and I cut way back on the beer. But now, I'm turning into a health nut. Not too fast; I don't want to deprive myself to the point of suddenly scarfing down a plate of ribs and a bucket of ice cream. But several subtle things that aren't really noticeable but make for a much healthier lifestyle. I'm just 5 pounds over what I weighed when I graduated college; now at 148lb. (5' 8").

Hitting the gym this winter when it's cold and dark now sounds like a wonderful idea as it'll help my bicycling.

akarius

You've got me curious with the G6PD deficiency. I thought that G6PD deficiency was usually a short-lived episode that is much more prevalent in neo-nates? I understand that using mesoporphyrin can treat its effects. Now I know that the original poster did not say that this was the case, just that it was a "genetic disease".

If it is a thyroid disorder would that not be easily taken care of by oral thyroxin? I am curious that if these were the cases why was the baby not treated earlier with these interventions? I know there are many things we do not know about this baby only what the poster has said. The parents could not have brought their baby to the doctor because of costs ect...

You post has sparked my curiosity and I was wondering if you could expand G6PD deficiency hypothesis

DannoXYZ 

I haven't seen the particular show that Kuan was talking about, so I just pulled some CHO metabolism problems babies have off the top of my head. I'm not exactly sure what complications that particular baby had. I think the show is called "Fit or Fat: Preventing Childhood Obesity" and it's on Discovery again on 17-Oct-05 at 7am EST. Another good show may be Escaping Obesity: Kathy's Story .

The rates of G6PD also varies by race and is most common in Africa with a frequency of about 10% in males and 8% in females. In the US African-American population, it's about 1/4th of that. It appears that the individuals with G6PD also have increased resistance to the malaria parasite, so it's a pyrrhic victory. Then the various "-quine" anti-malarial drugs ends up causing reaction that triggers hemolytic anemia in these individuals.

In the adult population, latest estimates indicate that 100 million Americans are overweight or obese. The average adult American's weight has increased by 25 lbs since 1960. This is within a SINGLE GENERATION! So I doubt there's anything genetic going on. I haven't been able to find any test data as to what percentage of this overweight/obese population has a true disease such as hypothyroidism , insulin resistance, polycystic ovary or Cushing's syndrome which can contribute to weight gain. I suspect it's less than 1%.

Now here's an interesting tidbit I suspect may be partially responsible: SSRI antidepressant drugs like Prozac, Zoloft, Paxil, Celexa, Wellbutrin may be implicated. These drugs elevate serotonin levels and stimulate the secretion of cortisol. With the tremendous explosion in the use of these drugs, we're seeing prevalent displays of their side-effects such as: irritability, decreased stress-handling capabilities, muscle-weakness, bone-demineralization, fluid-retention, hypertension, acne, ulcers, decreased immune response, glucose intolerance. This last one can also lead to diabetes, which has increased by +70% amongst adults 30-40 years-old in the last decade alone! Sure, you can't show a direct 1:1 relationship, but the tendencies and trends of cause & effect certainly seem to go hand in hand...

akarius

It is interesting that you mention these diseases, it would also be interesting to know how many people think that obesity is really a disesase out of their control, like Cushing's syndrome. Where in Cushing's syndrome it seems in most cases there is a cure, and the weight gain is negated.

It strikes me as odd that the general public is being informed that obesity caused by a poor life style is a disease, it seems when some people hear the word disease there is an association that there is a pill or medical procedure that can cure it of these disesases can be controlled, Of course obesity due to a poor life style is much harder to cure because the intervention needed must dominate the whole persons life, and not just a pill taken with meals, or on an empty stomach.

netso

Taking in 2000 Kilocalories does not mean you absorb 2000 Kilocalories. Digestion is about 50% efficient, absorption about 55% efficient.

bbattle

Americans are fat because we no longer do much manual labor and we eat way too many foods filled with worthless calories due to overprocessing. Too much sugar, too much junk food, no exercise.

DannoXYZ 

It also varies based upon what you're eating. The efficiency of carb, protein, fats conversion to ATP to drive the muscles is different. Here's a study that comes up with some figures:

Energetic Efficiency of Starch, Protein and Lipid Utilization in Growing Pigs
Carbohydrate Food Intake and Energy Balance - Absorption of fat is 96-98% efficient.

Perhaps one of the perks of the Atkins diet was that protein-utilitization by the body is so inefficient, you can eat more meat (although there are other complication that's introduced with such a diet).

netso

During the aerobic range most of the energy is provided by fatty acids. This is a great way to burn fats. Proteins are definitely not for energy, they are difficult to digest, many of the enzymes for their breakdown are missing. We tend as a society to eat too much protein. Everything needs to be converted to a 6 carbon sugar to go through the Krebs Cycle. Cycling is primarily an aerobic exercise, which is great. There is no excuse in the main to be fat!!!!

Wind 'N Snow

You've just hit on a growing diet fad!

I've had Hypothyroidism for years without knowing. Other than not being able to keep weight off when I wasn't excercising like mad, my body mostly adjusted, symptoms like dry skin etc. Now I take these little hormone pills and things have regulated themselves, more or less. although I still excercise (bike) like mad.

I understand that these hormones, thyroxin - or synthroid (https://www.synthroid.com/patientinfo/menu0.jsp) or versions thereof are being prescribed to people for weight loss - people who don't necessarily have a hormone imbalance.

I wish I didn't have to take these pills - I can't imagine anyone voluntarily taking them.

Alex33

If it's the same show I saw, it's about an English kid. I remember them explaining that his condition is so rare that there were only about 4 documented cases and only one other patient still alive, somewhere in South America (I think I got it right). It took the doctors years to diagnose it and it was only diagnosed right after the case was presented at a medical conference. It was definitely not your run-of-the-mill genetic disorder. FWIW

Pedal Wench

Oh my god! I thought I was losing my mind! I'm a relatively smart person, engineer and writer, but I've experienced the same thing! To do my unsupported centuries, I would have to double-back on a trail. I've got a computer on my bike and the bike trail is marked every half mile. Towards the end of my rides, for the life of me, I couldn't figure out how much further I needed to go out so when I turned around, I would have 100 miles at my car. Countless times, I would still end up doing loops in the parking lot to hit 100. Now I know!