Questions tagged [fat-metabolism]

The set of biochemical processes involved in the creation and utilization of lipids.

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Synthesis of Fatty Acids Longer than 16 Carbons

I understand that the human body when performing Fatty Acid Synthesis can synthesize only until C16 (palmitate). However the ER has desaturases and elongases. I know that desaturases are used to add ...
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What is/are the molecular differences between HDL and LDL cholesterol?

Why exactly is HDL-cholesterol good for us and LDL-cholesterol bad for us. It has been well-established that LDL-cholesterol is associated with atherosclerosis and that HDL-cholesterol helps remove ...
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What animal has fat with the highest energy density?

Fat is more energy-dense than protein and carbohydrates, it is not only an energy deposit but also an organ with many functions such as cushioning and metabolism regulations. I want to know are animal ...
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If eating 100% fat 2 times more worth the energy I spend during the day, will I store body fat?

So in theory, insulin hormone is the one that tells the body "eat more. don't burn body fat". Alongside with glucose blood level regulation and turning excessive glucose into liver (which later goes ...
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Is palmitic acid really that dangerous?

According to Wikipedia, "Palmitic acid is the most common saturated fatty acid found in animals, plants and microorganisms. It is also the first fatty acid produced during fatty acid synthesis and is ...
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Why are mammals unable to produce Essential Fatty Acids?

Why do we have to get them from our diet, and if they aren't taken in our diet we will face disease? Then why we don't have the enzymes which are require for EFA synthesis?
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Burning fat transferred from one part of the body to another

While doing some research on cosmetic surgery, I discovered that there are several ways of doing breast enhancements, one of which was using body fat. While I haven't researched this method, I assume ...
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Can the human body create glucose out of fat?

I read conflicting views about whether or not the human body can create glucose out of fat. Can it?
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Why do humans lose subcutaneous fat tissue with age?

Why exactly do humans lose subcutaneous fat tissue with age? It appears that we either lose fat cell volume or we might actually be losing the number of fat cells with age. One hypothesis is that as ...
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naturally occuring fatty acids

The double bonds in naturally occurring fatty acids present in our body are in cis configuration while the enzymes for beta oxidation can act on trans double bond. Then what will be the significance ...
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Can lactate be created in ketosis?

After looking at Cori Cycle (from wikipedia) I have a question about how the lactate can be produced in ketosis. According to this article: in a low-glucose state, where the body senses that ...
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99 views

Is returning cholesterol to the liver really performed by HDL?

Various answers in biology SE, including two quite upvoted ones (1, 2) claim that (in humans) returning cholesterol to the liver is done by HDL. If I understand correctly, Wikipedia's Reverse ...
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Cholesterol's role in lipid uptake [closed]

I'm studying the digestion of fats and I understand that our dietary fats mostly consist of triglycerides. We absorb the fats and eventually they end up in a muscle/adipose cell for storage (as ...
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How can grass-fed livestock generate fat?

How can herbivorous cattle get fat? These animals eat only grassy substances, think of cattle, buffalo, goats etc. For example, wheat grass contains 0% fat, and its nutritional value is limited to ...
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Breathing faster to lose (more) weight?

I understand that when the human body loses weight, the vast majority of that weight is lost as $CO_2$ (and a small bit is lost as water). I expect the predominant way $CO_2$ exits the body is through ...
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How does the human body extract energy from ethanol?

I was talking about alcohol and obesity with a colleague. I always thought the only cause of that is the sugar that is found in most alcoholic beverages. But my colleague pointed out that ethanol ...
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324 views

Bodyweight loss vs calorie shortfall

I have read that 1g of pure fat has 9 Calories. If I dieted successfully in a way that did not cause me to loose muscle, and I had a cumulative calorie shortfall of 90,000 calories. Would that ...
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Can bacteria metabolize fatty acids for fuel?

I'm not a microbiologist, but rather a physiologist curious about microbial metabolism. Much like humans bacteria can utilize glucose, but when it comes to long chain, medium chain, or short chain ...
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Where does weight go when you lose it? [duplicate]

When one loses weight, where does the lost poundage (I assume comprised mainly of fat) go? Is it urinated out? Defecated out? If a combination of both, does the percentage of each differ depending on ...
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What are the benefits of statins in terms of prolonging life?

Recently the UK government suggested that all adults over the age of 50, without exception, would benefit from taking statins. I have an elderly female relative who may, or may not have had a minor ...
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After fat is burned from one part of the body, is fat moved around the body?

If you go running, for example, and burn fat from your legs, does your body send fat from other parts of the body to that area? If so, why would it do this?
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What are the differences between carnitine forms?

I've heard of L-carnitine, acetyl L-carnitine and L-carnitine L-tartrate. What form(s) occur in meat? What form does the human body manufacture? Is L-carnitine just a shortened name for L-carnitine L-...
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Fatty Acid Synthesis

I have a problem in my reasoning on the fatty acid synthesis in the human body. In the synthesis process you have this homodimer. So the synthesis starts with the transfer of a acetyl group from ...
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How does the inability to produce vitamin C helped weight gain?

I recently wondered how do dogs cope without vitamin C intake like us. A few Wikipedia pages later, I learned that our dry-nosed ancestors lost about two-thirds of the gene responsible for vitamin C ...
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Extra-mitochondrial conversion of Acyl Carnitine to Acyl CoA

Normally fatty acids in the form of acyl CoA are converted to acyl carnitine in a reaction catalysed by carnitine palmitoyltransferase I (CPT1), which is also known as carnitine acyltransferase I. ...
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603 views

What happens when we eat excess fat?

The fats in our body are stored in fat cells. When we over eat fats does the size of our fat cells increase, are more fat cells generated, or do we "throw out" excess fat?
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How does the body determine where to deposit fat reserves?

People's bodies store fat in similar areas, but often there are subtle differences in which areas are first or slightly more effected. This seems to also be apparent with morbidity, where certain ...
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What is the function of CETP?

I read up that CETP transfers cholesterol from HDL, which collected it from tissues, to VLDL. This VLDL is then sent back to the tissues, ultimately forming LDL internalised by cells. What is the ...
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What is inside IDL (intermediate density lipoproteïn)?

I am studying about the endogene lipidcycle in the human body and I know that VLDL (very low density lipoproteïn) is made in the liver and that it contains triglycerides and cholesterol from your food ...
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Why are fatty acids consisting of even number of carbons predominant?

Most of the fatty acids in animal biology consist of even number of carbons in its parent chain. What property of such fatty acids cause the biological systems to prefer them over the odd counterparts?...
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Is there an evolutionary advantage for coconut oils to be rich in saturated fats?

I know that coconut oil is composed of multiple saturated fatty acids, but is there a reason why this would have increased the fitness of the coconut plant?
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Why is glycerol kinase absent from adipocytes but present in the liver?

Why don't adipocytes have the enzyme, glycerol kinase? Wouldn’t it be more efficient for them to utilise glycerol present to synthesize triglycerides than to get it from the liver? So what is the ...
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How would a medication cause a one to maintain a different weight?

This isn’t really a medical question, I’m just really curious about this. I was maintaining weight A and then started taking a medication that brought me to weight B. While on the medication, I ...
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Does the body prioritise the use of available sugar before fat?

Let's say you eat a very unhealthy snack that contains 90% sugar and 10% fat. Would somatic cells not start using the fat for energy until all the sugar is used up? Does the body not use fat at all ...
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Metabolic efficiency for fats and sugars

I am making an exercise for physics students about the first law of thermodynamics, burning heat and evaporation heat. So my idea is to use cycler which runs on fats and sugars where proportion ...
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Is there any disadvantage to having a really low adipocyte count in our times?

The key feature of adipocytes seems to be energy storage. Today humans in Western countries don't have to hunger and have therefore less need to store energy in fat cells. Do adipocytes have ...
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Could certain drugs enable one to consistently eat above TDEE or BMR without fat gains?

I heard anabolic steroids and stuff like DNP and ephedrine and etc. can somewhat enable one to eat more and get away with it without much or any fat gain, despite eating more than the body would ...
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Is there a relationship between HDL-C and LDL-C?

For a gentle introduction to cholesterol and its functions, see a great answer on SE Biology Whenever I read about how to deal with cholesterol level, the rule is to keep a low LDL fraction, ad a ...
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Lipids that are not found in human body

I know that human body contains FA some of which are essential and the other is not depending on the ability of the body to synthesize them in a sufficient amount, but I need a reference of the lipids ...
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Is the amount of cholesterol the body produces affected by how much cholesterol you take in with food?

In the past I've been told multiple times that if you don't eat foods containing cholesterol, your body will increase its production of cholesterol to balance out the lack of nutritional cholesterol. ...
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What is the rationale behind reverse cholesterol transport?

Reverse cholesterol transport is transport of cholesterol from the tissues back to liver/VLDL. My question is why do the tissues have this extra cholesterol in the first place? Why would you ...
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473 views

How much energy would it cost to synthesize all cholesterol requirements de novo?

Imagine a scenario in which some person is unable to absorb any dietary cholesterol because of some intestinal mutation (for example). Thus, they have no cholesterol available from their diet for ...
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Why doesn't the body optimize how many fatty acids it burns?

Ketone bodies are produced due to an excess of fatty acids being burned (accumulation of acetyl-CoA) so my question is: Why doesn't the body simply regulate how many fats it burns so it doesn't have ...
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What would happen if most the fat in your body was rapidly converted into energy in 2 minutes? [closed]

It all started out as an argument I had with my friend.He said that "it would be the equivalent of catching a fire and burning" But all I thought would happen is that you would now be very hyper ...
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When consuming carbohydrates and fats together, why are the fats caloric?

If I understand things, and I most likely don't: mammals primarily use carbohydrates to produce metabolic energy when there are sufficient carbohydrates to do so. The use of fats for fuel requires ...
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What is the source of the fat in adipose tissue?

I have heard the opinion that all of it comes from de novo lipogenesis of carbohydrates, but I'm skeptical. Is there evidence either way - either that dietary fat definitely gets stored in the adipose ...
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Is there such substances that body can only send to storage (as fat)?

I watched video with statement that there are such part of substance in potato chips which body can't use ("empty calories"), that they surely will be stored as fat. It was here on 12:23: https://...
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Fate of Acetyl CoA in well fed state?

When we have eaten well and take fat rich diet then in this condition Acetyl CoA produced from fatty acid breakdown will be gone to storage in adipose tissue or not? If it will go for storage then why ...
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Why do humans lose subcutaneous fat from the extremities with age?

Why does fat tissue die and shrink on the hands, knees, and lower legs of most people as they age, even when they are overweight? In most people, their bone definition becomes much more visible around ...
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What happens to lipoprotein lipase after a sugar only diet?

Insulin increases the activity of lipoprotein lipase thay allows cells to take in lipids from chylomicrons in the blood. If a person takes a sugar only meal like drinking coke, insulin is released. ...