15
First of all, we should specify that there is no such thing as "HDL-cholesterols" and "LDL-cholesterols". On the same note there is no such thing as "good cholesterol" and "bad cholesterol": cholesterol is just one molecule, with this chemical structure
What blood tests generally report is HDL-C and LDL-C, that is the amount of cholesterol in HDL or LDL ...
14
In both humans and animals, the body fat stores appear as triglycerides, which can be composed of different fatty acids, but they all have about 9 kilocalories per gram (USDA).
There can be different amounts of fat in different fat cells, so there can be slightly different amounts of fat in 100 grams of different types of fat tissue.
Calories in 100 g of ...
12
Only about 5–6% of triglyceride (fat) can be converted to glucose in humans.
This is because triglyceride is made up of one 3-carbon glycerol molecule and three 16- or 18-carbon fatty acids. The glycerol (3/51-to-57 = 5.2–5.9%) can be converted to glucose in the liver by gluconeogenesis (after conversion to dihydroxyacetone phosphate).
The fatty acid ...
9
Short answer
Plants typically store energy in the form of starch. Animals, including livestock and humans for that matter, can digest starch, metabolize it into acetyl-CoA and turn it into fat.
Background
Plants contain sugars, formed by photosynthesis. Plants generally do not store energy in the form of fats, but in the form of starch, a glucose ...
8
Let's first clarify some concepts. Free fatty acids, including palmitic acid, are not present in animal tissues (or in the diet) to any large extent; they are esterified with glycerol to from triglycerides (fat), which is the storage form. This is a very important distinction, because triglycerides are chemically inert molecules that can be stored in very ...
8
In short, it's because fatty acids are made from two-carbon blocks.
The way that most organisms make fatty acids is by the successive addition of two-carbon units (acetyl-CoA). So we usually get even-numbered fatty acids just because the building blocks are also even.
In plants and in synthetic contexts, we can have some reactions that can produce odd-...
7
as CO2 and water
in respiration sugar (or fat) is combined with oxygen to produce energy(ATP and heat), water, and CO2.
fats are converted to Acetyl Co-A just like glucose is, the rest of the metabolic pathway is exactly the same.
7
Many of the statements in your question are false, including your ideas about waste products.
Ultimately, fats, just like carbohydrates, end up as water and carbon dioxide if they are used in cellular respiration for energy. The reaction path is different, but the ultimate reaction products are the same as you would get from burning fat in a fire: reaction ...
6
You hit upon several ideas in your post. First, you are absolutely correct that body fat is composed both of lipids and water, so a 10kg weight loss does not correspond to 90,000 kcals. The most commonly accepted figure is 7700 kcals per kg of body fat lost (Hall, 2008), but this is a rule of thumb at best.
The translation from caloric deficit to body fat ...
6
There are a couple of reasons why this approach doesn't work quite as well as you might hope.
First, insulin doesn't go away after a high-fat meal. This paper reports changes in serum insulin following pure-sugar and pure-fat meals. Although there is much less of an increase in insulin following the pure-fat versus the pure-sugar meal, you will notice in ...
6
Preamble
The question suggests unfamiliarity with the nature of biochemical oxidations and their relation to energy transfer in biology. The naïve reader is recommended to consult a text for a coverage of this subject: all I feel is appropriate here is a general summary followed by a brief indication of the key reactions.
General principles of energetic ...
5
The rate of CO2 production is normally set by the rate of metabolism and breathing rate is determined by the level of CO2 in the blood. What you are suggesting is known as hyperventilation. Because blood CO2 plays an important role in maintaining the pH of the blood, hyperventilation can lead to a dangerous increase in blood pH, referred to as respiratory ...
4
The diversity of fatty acids produced by an organism is limited by the diversity of enzymes which synthesize them. Unsaturated fatty acids contain carbon-carbon double bonds which do not isomerize. The capacity for humans to produce cis fatty acids is probably selected for because of their lower melting point which prevents arterial clogging. Cold blooded ...
4
Would the body use this transferred fat for as energy, or would it
ignore it as it wasn't stored there in the first place?
It would use it as energy source, there is no such thing as "ignored tissue". Fatty acid mobilization is regulated by epinephrine and insulin. These are hormones which are ofc. carried by blood, so every white adipose (fat) tissue is ...
4
It depends, but you're going to die.
Specifically, it depends on how fat you are. Even Andreas Munzer is going to die. At only 3% body fat, burning all his fat (9kcal/g) would "only" increase his internal body temperature by 270 degrees C. Factoring in the energy required to boil off his body moisture and adding in body heat leaves Andreas at ~200 C or so (...
4
This is entirely speculation, but the part of seeds that is pressed for oil(the endocarp) is enriched in saturated fats and long fats in ocean-going fruits. The coconut is 91% saturated fats, the oil palm is about 50%, etc. The tamanu or 'ballfruit' produces monounsaturated long-chain fatty acids in the endocarp, about 75% C18 oils, mono- or di-unsaturated....
4
I found this review about bacterial lipid metabolism. There it says:
Exogenous long chain fatty acids are utilized by E. coli in two ways. Firstly, they can
be incorporated into the membrane phospholipids by the acyltransferase system (PlsB
and PlsC; Section 4). Secondly, they can be used as the sole carbon source for growth,
and are in fact an ...
4
Short answer
We do not loose fat (cells) as we age; on the contrary - we tend to gain fat by about 1 or 2% per decade. The place where it gets stored does change; instead of going into subcutaneous regions, it gets stored around the abdomen. A sex hormone imbalance might be the cause of this gain in visceral fat.
Background
What a coincidence! I just ...
3
Same way animals can turn sugars to fats, chain reactions involving multiple enzymes. Some plants, e.g. potatoes, rice etc. will store very little fat. Most plants will only store a bit of fat in the seeds, but some - I guess nuts and olives are the main ones - will convert significant amounts of glucose (produced by photosynthesis) to fats, which we can eat,...
3
To be more detailed it is the irreversibly of the reaction carried by Pyruvate dehydrogenase that makes the conversion of the fatty acid chains to glucose impossible.
The fatty acids chains are converted to acetyl-CoA.
Acetyl-CoA to be converted into pyruvate need an enzyme that can do the Pyruvate Dehydrogenase's inverse reaction (in humans there is no ...
3
Here's a study in which they measured a decrease in endogenous cholesterol synthesis after various amounts of dietary cholesterol: Dietary Cholesterol Feeding Suppresses Human Cholesterol Synthesis Measured by Deuterium Incorporation and Urinary Mevalonic Acid Levels (Arteriosclerosis, Thrombosis, and Vascular Biology, 1996):
The objective of this study ...
3
The short answer to this question is given in the Wikipedia article on glycerol kinase:
Adipocytes lack glycerol kinase so they cannot metabolize the glycerol produced during triacyl glycerol degradation. This glycerol is instead shuttled to the liver via the blood where it is: phosphorylated by glycerol kinase to glycerol phosphate and/or converted to ...
3
First, there are inaccuracies and misconceptions in the article you quote, which also relates to obese people with insulin-resistance (pre type II diabetics) rather than normal people. These are:
I’m not sure what a “low glucose state” is supposed to mean, but the tissues of the organism co-operate to ensure that the blood glucose concentration normally ...
3
Carnitine tartrate is a salt between carnitine (cation) and tartrate (the conjugate base of tartaric acid, anion). So in this case, tartaric acid is not covalently bound to carnitine.
The salt formulation is a little tricky, because carnitine is itself a zwitterion at physiological pH (it has both a positive and negative charge) and so is overall uncharged ...
3
I suspect I won't be crunching as much numbers as you'd want me to, however here are some basic points:
Statins have shown a clear ability to improve the blood llipid profile.
Their use in primary/secondary prevention for cardiac events is justified by the belief that less blood lipid will leave less lipids to clog the arteries with. This is an old paradigm,...
3
Omega 3 Fatty Acids cannot prevent the the acute symptoms of periodic A Fib, nor is there a role for vitamin D in the treatment of acute symptoms of periodic AF.
Atrial Fibrillation with the symptom of chest pain is very worrisome and requires urgent or emergent treatment. The most common treatments are heart rate control via IV antiarrhythmics, or ...
3
You breath it out, for the most part. Fat is "burned" to convert the carbons to CO2, which is breathed out. There's not very much fat-derived carbon in each breath, but you breath a lot, all day long.
At rest, an average 70 kg person consuming a mixed diet (respiratory quotient 0.8) exhales about 200 ml of CO2 in 12 breaths per minute. Each of those ...
3
This is simplified version of a complex situation, but in summary:
A key role of liver is to control the distribution of metabolic fuel
for the other tissues (it always has enough for its own
requirements).
The way it behaves differs in the fed and fasted states (because of control by hormones and the concentration of metabolites).
In the fed state (after ...
2
The textbook descriptions of fatty acid synthesis can be confusing because although the underlying chemistry of the process is universal, the way that it is organised is different in the systems that have been characterised, which include E. coli, yeast and vertebrates.
In vertebrates:
The fatty acid synthase is a dimer of identical multifunctional single ...
2
Short Answer: Yes.
Long Answer: See this article:
The diagrams presented show how fatty acids are synthesized in microorganisms and list the enzymes found in Escherichia coli. These reactions are performed by fatty acid synthase II (FASII), which in general contain multiple enzymes that act as one complex. FASII is present in prokaryotes, plants, fungi, ...
answered Apr 19 '16 at 10:49
another 'Homo sapien'
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