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  #1  
Unread 12-05-2012, 07:53 PM
Primalkid Primalkid is offline
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Default MCT metabolism & meal composition

So Lyle states many times that MCTs are ideal for cutting especially for already lean individuals, etc. Searches of the forums has led me to the conclusion that its do to a slight thermogenic effect. Furthermore, MCTs bypass the lymphatic system and enter the blood stream to be preferentially burned for energy.

My question is how does consuming MCTs with a meal affect metabolism. For instance, coconut is roughly 50-67% MCTs. If I eat some coconut with a high carb meal, would the insulin response shuttle the MCTs away? Or do they get burned even before carbohydrates?

I know this post is a little difficult to understand, I am having trouble writing what is in my head. Basically, I am curious about meal composition and how the nutrients effect one another with regard to MCTs/Coconut.

And since I am currently bulking, is there any benefit to swapping some of my fat with MCTs? Or should I just stick with unsaturated fats (Lyle says that saturated fat is harder to mobilize in the stubborn fat book).
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  #2  
Unread 12-07-2012, 12:57 PM
Primalkid Primalkid is offline
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I did some digging around PubMed, and found this study:

http://www.ncbi.nlm.nih.gov/pmc/arti...00123-0133.pdf

Quote:
Plasma glucose concentrations reached a peak after 45 min in each of the three tests. The rise in glucose concentration was somewhat attenuated by the presence of fat in the meal, though this effect reached statistical significance only with MCT, 30 min (P < 0.05) and 45 min (P < 0.01) after the meal. Subsequent differences between average blood glucose levels were not statistically different after the three test meals.
It appears that MCTs might lower the peak glucose concentrations? Thoughts?

Quote:
The absorption and transport of MCT occurs by other mechanisms than those involved for the naturally predominant long-chain fatty acids (25). Instead of being incorporated into chylomicrons, medium-chain fatty acids appear in the portal blood as FFA bound to albumin (26), the form in which all fatty acids are typically made available to tissues for energy generation. Thus, they would be expected to be more readily used for energy generation, as well as less effectively trapped by adipose tissue where their esterification and storage may in fact require prior conversion to fatty acids with longer carbon chains (27). Indeed, the lesser increase in the RQ observed early after the MCT meals (Fig. 2) reveals that ingestion of MCT promoted fat oxidation in the postprandial phase, which resulted in the sparing of some 10 g of carbohydrate (Fig. 5).
MCTs also appear to be burned for energy regardless of carbohydrates (although the effect is minimal). Thoughts?

This other study seems to support these findings as well

http://ajcn.nutrition.org/content/74/5/620.long
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  #3  
Unread 12-09-2012, 06:14 AM
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From what I gathered, MCT's were a good way to provide acute energy (in place of carbs) when doing a no carb diet.

I see this is a functional/ psychological tool for when you need a bit of a boost.

I don't really see how any changes in metabolic rate are relevant? I assume it would be insignificant in the grand scheme of your energy in energy out

Last edited by Hectic : 12-09-2012 at 06:19 AM.
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  #4  
Unread 12-09-2012, 03:10 PM
Primalkid Primalkid is offline
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Quote:
Originally Posted by Hectic View Post
From what I gathered, MCT's were a good way to provide acute energy (in place of carbs) when doing a no carb diet.
Yes.

Quote:
I don't really see how any changes in metabolic rate are relevant? I assume it would be insignificant in the grand scheme of your energy in energy out
Probably, but my focus is how MCTs interact with other nutrients. For instance, it is known that carbs = insulin = fat storage. Yet MCTs are burned like carbs. So if you ate both carbs and MCTs would the body still burn the MCTs? Or would the insulin treat them like normal fats?
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  #5  
Unread 12-09-2012, 03:49 PM
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Well all your fats (apart from MCT) get stored first anyway, so insulin or not they still get stored.

On a cut the carbs will be burned and stored as glycogen temporarily until they get used. Your fat storage doesn't matter because your burning more than you store.

On a bulk the carbs will be burned or stored as glycogen and the excess fat will not come out of storage to be burned thus leaving you with a net fat gain. Same thing would probably happen with MCT? The rest of the excess fat in your diet will stay in storage while you eat MCT's.

Considering insulin and carbs is what helps you grow/recover/ optimise hormone levels, I'd hardly consider swapping them out for something that doesn't do that.

Insulin is your friend. Drug users pay a lot of money to take insulin. There's only 4 reasons I can think of for why you would want to limit insulin release.

1. For satiety/ diet adherence reasons: to stop your blood sugar from swinging and giving you cravings
2. Before exercise designed to acutely burn fat (this may or may not even be an issue can't remember)
3. If you are a glutton and cannot control your food intake and eat way more carbs than your body will ever burn. In this case you have more important things to worry about.
4. If you have diabetes

Last edited by Hectic : 12-09-2012 at 04:03 PM.
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  #6  
Unread 12-09-2012, 04:40 PM
Primalkid Primalkid is offline
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Quote:
Originally Posted by Hectic View Post
Well all your fats (apart from MCT) get stored first anyway, so insulin or not they still get stored.
Fats are constantly being stored and mobilized throughout the day, regardless of nutrient intake (or lack thereof).

Quote:
stored as glycogen temporarily
no

Quote:
Same thing would probably happen with MCT? The rest of the excess fat in your diet will stay in storage while you eat MCT's.
Interesting thought, I would love to see some science to support this.

Quote:
Considering insulin and carbs is what helps you grow/recover/ optimise hormone levels, I'd hardly consider swapping them out for something that doesn't do that.

Insulin is your friend. Drug users pay a lot of money to take insulin. There's only 4 reasons I can think of for why you would want to limit insulin release.

1. For satiety/ diet adherence reasons: to stop your blood sugar from swinging and giving you cravings
2. Before exercise designed to acutely burn fat (this may or may not even be an issue can't remember)
3. If you are a glutton and cannot control your food intake and eat way more carbs than your body will ever burn. In this case you have more important things to worry about.
4. If you have diabetes
This is totally irrelevant to the discussion. I am not against insulin or carbs. As I stated earlier, I am interesting in learning more about nutrient interactions with MCTs.
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  #7  
Unread 12-09-2012, 07:21 PM
NeuropeptideWhy NeuropeptideWhy is offline
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Quote:
Originally Posted by Primalkid View Post
It appears that MCTs might lower the peak glucose concentrations? Thoughts?
That study had the opposite result of what I would have hypothesised, because because consuming MCT+CHO actually speeds up gastric emptying rate compared to CHO alone (Beckers et al 1992), so you might expect elevated plasma glucose when consumed with MCTs.

Indeed, in one study, although MCT+CHO had no effect on peak plasma glucose during rest, MCT+CHO actually increased the peak plasma glucose during the initial stages of exercise compared to CHO alone (Horowitz et al 2000).
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  #8  
Unread 12-09-2012, 11:48 PM
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Quote:
Originally Posted by http://www.ncbi.nlm.nih.gov/pubmed/8567514
The present study examined the metabolic response to medium-chain triglycerides (MCTs) ingestion with or without carbohydrates (CHOs). Eight well-trained athletes cycled 4 x 180 min at 50% maximal work rate (57% maximal O2 consumption). Subjects drank a bolus of 4 ml/kg at the start and 2 ml/kg every 20 min during exercise of either a 15% (214 g) CHO solution (CHO trial), an equicaloric 149 g CHO-29 g MCT suspension (CHO+MCT trial), 214 g CHO [high CHO (HCHO)]-29 g MCT suspension (HCHO+MCT trial) or 29 g MCT solution (MCT trial). Exogenous MCT oxidation was measured by adding a [1,1,1-13C]trioctanoate tracer to the MCT oil. 13CO2 enrichment of breath samples were measured every 15 min. During the second hour (60- to 120-min period), the amount of MCT oxidized was 72% of the amount ingested during the CHO+MCT trial, whereas during the MCT trial only 33% was oxidized. The rate of MCT oxidation increased more rapidly during the HCHO+MCT and CHO+MCT trials compared with the MCT trial, yet in all three cases the oxidation rate stabilized at 0.12 g/min during 120-180 min of exercise. It is concluded that more MCTs are oxidized when ingested in combination with CHOs. Data do confirm the hypothesis that oral MCTs might serve as an energy source in addition to glucose during exercise because the metabolic availability of MCTs was high during the last hour of exercise, with oxidation rates being approximately 70% of the ingestion rate.(ABSTRACT TRUNCATED AT 250 WORDS)
Quote:
Originally Posted by http://www.springerlink.com/content/v527511673547k29/
Medium-chain triglycerides (MCT) are known to be rapidly digested and oxidized. Their potential value as a source of dietary energy during exercise was compared with that of maltodextrins (MD). Twelve subjects exercised for 1 h on a bicycle ergometer (60% V O2 max), 1 h after the test meal (1MJ). The metabolism of MCT was followed using 1-13C-octanoate (Oc) as tracer and U-13C-glucose (G) was added to the 13C-naturally enriched MD.
After MCT ingestion no insulin peak was observed with some accumulation of ketone bodies (KB), blood levels not exceeding 1 mM. Total losses of KB during exercise in urine, sweat and as breath acetone were small (<0.2 mmol·h−1). Hence, the influence of KB loss and storage on gas exchange data was negligible.
The partition of fat and carbohydrate utilization during exercise as obtained by indirect calorimetry was practically the same after the MCT and the CHO meals. Oxidation over the 2-h period was 30% of dose for Oc and 45% for G. Glycogen decrements in the Vastus lateralis muscle were equal. It appears that with normal carbohydrate stores, a single meal of MCT or CHO did not alter the contribution of carbohydrates during 1 h of high submaximal exercise. The moderate ketonemia after MCT, despite substantial oxidation of this fat, led to no difference in muscle glycogen sparing between the diets.
Quote:
Originally Posted by http://www.sciencedirect.com/science/article/pii/0026049589901017
To test whether excess dietary energy as medium-chain triglycerides (MCT) affects thermogenesis differently from excess dietary energy as long chain triglycerides (LCT)....Our results demonstrate that excess dietary energy as MCT stimulates thermogenesis to a greater degree than does excess energy as LCT. This increased energy expenditure, most likely due to lipogenesis in the liver, provides evidence that excess energy derived from MCT is stored with a lesser efficiency than is excess energy derived from dietary LCT.
Quote:
Originally Posted by http://jn.nutrition.org/content/132/3/329.full#ref-7
Fats varying in fatty acid chain lengths are metabolized differently (1–8). Medium-chain triglycerides (MCT),3 containing 6–12 carbon fatty acids, differ from long-chain triglycerides (LCT), which have fatty acids of > 12 carbons, in that they are absorbed directly into the portal circulation and transported to the liver for rapid oxidation (1). LCT, however, are transported via chylomicrons into the lymphatic system, allowing for extensive uptake into adipose tissue. Therefore, it has been hypothesized that the rapid metabolism of MCT may increase energy expenditure (EE), decrease their deposition into adipose tissue and result in faster satiety.
The reason MCTs are compared to carbs is because of this fact that their primary fate is to be metabolized (beta-oxidation) directly in the liver, their physical structure allows easier transportation around the body, and they are not readily stored as fat. Overall, they tend to facilitate weight loss better than LCTs.

In a practical example, let's say one were to consume hypercaloric diets of 20/40/40 protein/carbs/LCT versus 20/40/40 protein/carbs/MCT, the latter would probably result in less fat being stored. Unless, more carbohydrate gets stored as fat but that only happens when fat < 10%?

More reading:
http://www.jacn.org/content/27/5/547.full
http://www.ncbi.nlm.nih.gov/pubmed/1568535
http://ajcn.nutrition.org/content/79/4/564.full
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  #9  
Unread 12-10-2012, 06:06 AM
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Sorry I did not read your OP properly. So you are wanting to swap MCT's for other saturated fats (as opposed to carbs like I carried on about). I guess it seems irrelevant to me because my saturated fats come from stuff like meat low fat milk and ow fat cheese, so it's not like I can swap them out for coconut. I would never 'waste' my kilojoules on any type of saturated fat that was separable from the food I want to eat because i see it as rather inert as far as usefulness is concerned. For example I never eat butter simply because it doesn't do anything useful for my metabolism/ nutrition. I gather you are consuming some significant amount of saturated fat which you can substitute out for MCT's if desired.

Of course if I found butter particularly enjoyable to eat maybe i would try to fit it in. If i was you, it would be more of an issue of how much do I enjoy coconut.


Back to the irrelevant part:
Why would you say no to carbohydrates being burned and stored as glycogen temporarily on a deficit?

Where else can carbs go apart from blood glucose and glycogen?

Last edited by Hectic : 12-10-2012 at 06:25 AM.
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  #10  
Unread 12-10-2012, 10:17 AM
Primalkid Primalkid is offline
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Originally Posted by NeuropeptideWhy View Post
That study had the opposite result of what I would have hypothesised, because because consuming MCT+CHO actually speeds up gastric emptying rate compared to CHO alone (Beckers et al 1992), so you might expect elevated plasma glucose when consumed with MCTs.

Indeed, in one study, although MCT+CHO had no effect on peak plasma glucose during rest, MCT+CHO actually increased the peak plasma glucose during the initial stages of exercise compared to CHO alone (Horowitz et al 2000).
Yes I saw these studies but they deal with exercise, while I am interested in just eating a meal without sitting on a bicycle for the next hour =)

Quote:
Originally Posted by mahalin View Post
The reason MCTs are compared to carbs is because of this fact that their primary fate is to be metabolized (beta-oxidation) directly in the liver, their physical structure allows easier transportation around the body, and they are not readily stored as fat. Overall, they tend to facilitate weight loss better than LCTs.

In a practical example, let's say one were to consume hypercaloric diets of 20/40/40 protein/carbs/LCT versus 20/40/40 protein/carbs/MCT, the latter would probably result in less fat being stored. Unless, more carbohydrate gets stored as fat but that only happens when fat < 10%?
Yes I am aware of all this. To get to the liver though, they must enter the bloodstream first, which is where my thoughts on carbs came from. Carbohydrates stimulate insulin which prevents fatty acid breakdown and mobilization, so that the carbs can be burned for energy first. Does this apply to all fats? Or do MCTs get a gold pass that lets them be burned anyways?

From the studies I had posted earlier, it appears that consuming MCTs with carbs lowers the respiratory quotant, which means a higher level of fat oxidation compared to a group eating only carbs, and a group eating the same meal but with LCTs instead of MCTs.

Quote:
Originally Posted by Hectic View Post
Sorry I did not read your OP properly. So you are wanting to swap MCT's for other saturated fats (as opposed to carbs like I carried on about). I guess it seems irrelevant to me because my saturated fats come from stuff like meat low fat milk and ow fat cheese, so it's not like I can swap them out for coconut. I would never 'waste' my kilojoules on any type of saturated fat that was separable from the food I want to eat because i see it as rather inert as far as usefulness is concerned. For example I never eat butter simply because it doesn't do anything useful for my metabolism/ nutrition. I gather you are consuming some significant amount of saturated fat which you can substitute out for MCT's if desired.

Of course if I found butter particularly enjoyable to eat maybe i would try to fit it in. If i was you, it would be more of an issue of how much do I enjoy coconut.
Actually I never eat added saturated fats either, I more did this post out of interest. I get nearly all my fats from my protein sources, and if I do need a little extra to hit my macros it will usually be from macadamia nuts or avocado. Sometimes I will eat coconut meat.


Quote:
Back to the irrelevant part:
Why would you say no to carbohydrates being burned and stored as glycogen temporarily on a deficit?

Where else can carbs go apart from blood glucose and glycogen?
Sorry, I may have assumed you were referring to muscle glycogen. In a deficit, my understanding is that the carbs will be burned preferentially, but since not all carbs can be burned immediately and blood glucose is toxic, they are sent to the liver and stored as glycogen until the body needs them.
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