I just watched an episode of House and he diagnosed a girl with Cushing’s – an illness that can cause obesity.
How is that possible? I was under the impression that our bodies use energy we get from food, and if it doesn’t get the food it’ll burn fat resulting in us getting slimmer – how can a disease change that?
How does it not go against some laws of thermodynamics? Maybe I’m just being silly.
In: Biology
> I was under the impression that our bodies use energy we get from food, and if it doesn’t get the food it’ll burn fat resulting in us getting slimmer – how can a disease change that?
It doesn’t change that. But it changes the details.
A given amount of food has a fixed amount of chemical energy. But our body doesn’t extract 100% of that energy! Different bodies extract it at different rates.
Similarly, the same activities/lifestyle will cost different people different amounts of chemical energy.
So, a person eating the same amount and doing the same amount of exercise might end up with different actual energy dynamics.
That’s what the metabolism is (simplified, of course).
>I was under the impression that our bodies use energy we get from food, and if it doesn’t get the food it’ll burn fat resulting in us getting slimmer
That’s still true, but lots of things can throw a wrench in that process. Cushing’s, for example, is caused by an excessive amount of a hormone called cortisol. Hormones are a broad class of chemicals that regulate how bodily systems and functions work. Too much cortisol frequently causes in increase in appetite, which leads to overeating and weight gain, and also interferes with the body’s normal process of storing and braking down fat. In other words, it tells your body to do the wrong thing, sort of like a broken traffic light. Something like a tumor in the pituitary gland of the brain can cause your body to create too much cortisol, therefore leading to weight gain.
A lot of fat is burned through our system by our blood. If a disease effects the blood movement… it can stop fat from burning.
Cushing’s is a disease that increases the amount of cortisol in your body which is a hormone that tells your body to pump more blood during stressful situations. This hormone also helps tell the body to burn food and fat reserve.
Think of it like phone lines between two offices… your brain sends hormones down a line to tell the fatty cells to release the stored fat to increase the flow of blood; if the operator is wrong when telling the person on the other end to do a different job, the whole workplace gets effected.
realistically, there is still so much we don’t know about how the human body works. nothing is black and white. everybody has a different metabolism and lifestyle, the path you’re on now is how we get to people hating fat people.
every single aspect of the environment and our cells effects the way we process food, no two people are the same. throwing diseases into the mix can lead to an even more complex dynamic in the body. an example is that obesity is a cause of diabetes, but it is also a common symptom. logically that cannot be true, but realistically the human body is strange and processes things differently in every single person.
Replying to your thermodynamics comment, diseases and medications can alter calories burned in a vacuum.
What do I mean by this?
A person with low thyroid and low testosterone will burn less calories in a day than if they didn’t have the disease.
Here’s the important part. If some one takes T3 and testosterone they will burn more calories and lose more weight than the same person without those medications eating the exact same amount of calories.
This is without any differences in appetite or calories consumed.
There’s more details you can research about how someone with higher testosterone would have more muscle and burn more calories through thermodynamics as a healthy individual than a metabolism diseased person.
Even from a simple calories-in calories-out perspective, appetite changes (which are at least partly driven by hormones) tend to change the amount of food we consume. This increases calories-in, often significantly. Since hunger is one of the strongest drives for humans, it’s very, very difficult to just ignore it, but it can vary greatly between people and between situations.
PCOS is another example of hormones messing with weight. PCOS can cause excess insulin, which can make your body think it needs to store fat. It causes a much slower metabolism.
Some mental disorders (like depression for example) are quite closely correlated to eating disorders. This includes eating too much as well as not eating enough. So while it’s true you mostly gain weight from eating more, the disease itself makes the act of eating harder to control. One reason for this is it becomes a coping mechanism to deal with the illness, in a similar fashion how an addiction would work.
It’s easy to dismiss this as “oh, just eat less”, but being affected by those illnesses that kind of choice might be too hard to make.
Well just to start, thermodynamics has nothing to do with it. Nothing is actually being burned in your body; it’s a figure of speech.
Cushing’s syndrome is essentially any condition in which someone has excess cortisol (Cushing’s disease is one specific kind where one would have a pituitary tumor which secretes excess ACTH which stimulated excess cortisol production in the adrenal glands).
Excess cortisol can have various effects on metabolism. For example, it increases insulin resistance and gluconeogenesis. Both of which promote higher blood sugar. In the short term this is good for immediate use when exercising or whatnot but not when it’s chronic. One reason is because cortisol is acting everywhere it can to get as much glucose creates as possible, including using muscles (which is really noticeable when chronic). The extra blood sugar then stimulates extra insulin production.
This insulin (and cortisol) promotes additional fat formation with excess sugar, and the high cortisol levels also promotes a redistribution of fat in the body to more visceral fat. This inherently makes someone more likely to develop diabetes and obesity even if they eat the same as always.
However, cortisol release also promotes the release of ghrelin (hormone that promotes hunger) and inhibits leptin (hormone that promotes satiety), so the odds are really stacked against you. While something like chronic stress can also lead to increased cortisol release (which is one of the reasons why that’s a risk factor for obesity and diabetes btw), the amounts present in Cushing’s are in extreme excess, and it’s really not reasonable to expect someone to just “watch your diet, duh”.
So yeah obesity is one symptom of Cushing’s (in addition to hypertension and hyperpigmentation).
Antipsychotic drugs can cause metabolism changes that can continue even after you stop taking the drug. That’s one (there are several) reasons why people don’t like taking them, they can make you fat.
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