Question
Asked 21st Dec, 2012

Teaching the body to use fat as primary energy at rest - changing body composition.

As l have understood, fat is the primary source of energy that the body uses when an individual is at rest. However, l have read that the moment there is an intake of carbohydrates, the body shift to this source of energy and stops using fat. Also, l read that in order to make the body use fat as the primary source of energy at rest, one should try to eat many times during the day (i.e. 5 or 6), and these meals and snacks should contain low glycemic index carbohydrates, proteins and vegetables or fruits. Apparently, by doing so a peak of insulin is avoided and the body continues using fat as primary source of energy. Can anybody explain how exactly this happen? Would this be a good strategy in order to change an athlete´s body composition (if we want to decrease fat levels while maintaining lean muscular mass)?

Most recent answer

21st Oct, 2020
Craig Paardekooper
Kingston University
If you do any kind of sport you will soon realise that without carbs you feel sluggish and weak and tired. Try eating cheese for breakfast then doing a 5k jog. I guarantee that you will feel drained - grannies will literally over take you walking their dogs and ultra fat people will roll past you. However, if you have a bit of porridge then you can run like Chariots of Fire. Nuff said.

Popular Answers (1)

14th Sep, 2014
Nilesh Kate
Employees’ state Insurance Corporation medical college and hospital kalaburgi
Carbs = Sugar
Sugar in your food generally requires little to no digesting or processing and will be in your bloodstream inside 60 minutes after eating. In response, blood sugar shoots up for a bit before coming back down rapidly a short while later. Other
carbohydrates, referred to as complex carbohydrates, will be sugar in your bloodstream as well eventually. It takes your digestive system a little longer to convert complex carbs into simple sugars, so blood sugar will rise and fall a bit slower depending on a few factors. These include
the type of carbohydrate (how "complex" it is) and how fibrous and/or fatty the food is.
Once in the blood, your metabolism begins to use sugar in a variety of ways. Particularly if you are active or exercising, some of the sugar in your blood will be
used quickly for energy. Glucose and/or fructose are the end-products of all carbohydrate breakdown. These simple sugars enter into either glycolysis (for glucose) or fructolysis (for fructose). In these processes, the metabolism uses the simple sugars to generate the compounds
that, in turn, power all of the body's other metabolic processes. Put more simply, glycolysis and fructolysis convert simple sugars into energy.
(A quick note on fiber: fiber is classified as a type of carbohydrate and is listed on nutrition labels under the
carbohydrate section. Most fiber will pass through the body undigested. The remainder will be digested quite slowly over the course of many hours. Fiber does not have a meaningful effect on blood sugar.)
Insulin: The Storage Hormone
Most of the time, however, sugar is not used immediately but is stored in cells for use later. This is where insulin comes into the equation. Insulin is a protein that acts as a hormone in the digestive process. When a protein is classified as a hormone, it means that it's
presence in the bloodstream triggers a cascade of other related and interdependent processes in the metabolism. Insulin is perhaps the single most important element of nutrient metabolism, and understanding its function is critical for understanding what your body is doing with the food you eat. When
there is more sugar in the bloodstream than the body is immediately using, insulin is released and initiates the storage process. Insulin causes glucose to be absorbed into cells, upon which, it is stored in one of two ways. The primary storage method for glucose is as triglycerides in adipose
(fatty) tissue. The secondary method is as glycogen, essentially a matrix of glucose that is stored in muscle and liver cells for later use as quick energy, primarily in times of exertion.
To summarize, when you eat carbs they are broken down
into sugars by the digestion process. Sugar causes the release of insulin and insulin causes the sugar to be stored, primarily as fat in adipose cells. Particularly when forming a large portion of your caloric intake, carbohydrates are the primary source of any fat your body is storing.
Fueling With Fats
Fat digestion and metabolism happen via completely different pathways than the ones used for carbohydrate metabolism. The first major difference in the digestion of fats relative to
carbohydrates is that the breakdown and absorption is a much slower process. Most fats are broken down slowly in the gut via a series of enzymes called lipases and eventually make their way into the blood stream as free fatty acids. Like sugars, once in the bloodstream free fatty acids can be used for
energy (via the process known as ketogenesis) or stored in adipose (fatty) tissue for later use.
One notable exception to this digestion pathway is medium-chain triglycerides (MCT's). Because they are smaller than other fats, MCT's can pass directly into
the bloodstream without needing digestion in the gut by lipases. These smaller fats are broken down into free fatty acids by lipases in the blood rather than in the gut. While other types of fat take too long to digest and process to be a legitimate alternative to carbohydrate as a primary fuel source, the
quicker availability of MCT's makes them not only a legitimate alternative, but a preferable one. MCT's are also unique among fats in that they can be used by the brain for energy. Other types of fat must go through the long process of being converted into sugars before they can be used by the
brain. Eating primarily other types of fats would leave the brain under-fueled. Once again, MCT's and SCT's not only solve this issue, but offer a superior alternative to carbohydrate. Unsurprisingly, MCT's and SCT's are critical to any diet using fats as a the primary calorie and fuel source.
When your metabolism is using primarily fats as an energy source, you are essentially "training" your metabolism to use fats more often and more efficiently. The metabolic pathways involved in ketogenesis (fat-burning) become more robust, and the body
becomes better at using fat stored in adipose tissue when available sufficient calories are not available from food intake. Fats also don't directly trigger an insulin response, so the body doesn't go into "storage mode" as often when fats are your primary fuel source.
So what are the best sources of MCT's? Coconut oil (and related products) and grass-fed butter are hands-down the top choices. Coconut oil is about 2/3 MCT's by weight. In addition to it's many other benefits coconut oil is the go-to fuel source for many people adhering to this type of high-fat diet. A
few companies isolate the MCT's from coconut oil and sell "MCT oil" by itself. This is a pricy option as an every-day fuel source, but if you're looking to accelerate the fat-burning capacity of a this diet, MCT oil is a powerful tool. Coconut butter is also a great choice, as it is the "meat" of the coconut before
the protein and fiber is pulled out in the process of making coconut oil.
Additionally, grass-fed butter is an excellent source of short-chain fatty acids (as well as many vitamins and Omega-3 fatty acids). These short-chain fatty acids behave in much the same
way as MCT's and can be used for the same purposes. It is important to source only 100% grass-fed (sometimes called "pastured") butter. Conventional butter has a significantly different nutritional profile and is more likely to contain toxins.
Fats vs. Carbs
the metabolism tends to adapt to the types of fuel it is receiving most frequently. If the metabolism is being fueled disproportionately with carbohydrates, the metabolic pathways that use and store carbohydrates will dominate while fat metabolism pathways will
diminish. The reason for this is two-fold. The first reason is that the pathways required to store or use carbohydrates require a set of enzymes unique from those the metabolism uses to process fat. The body is remarkably good at not being wasteful and will decrease production of fat
metabolism enzymes when they are used infrequently. The second reason is that insulin specifically stops the use of fat for energy by inhibiting the release of glucagon, a hormone that increases blood sugar and thus directly competes with insulin.
Because of this "competition" between fat and carbohydrate metabolism pathways, fat will only be used for energy in the absence of insulin. If you're going to train your body to use fat for energy, it becomes critical to minimize both the magnitude and duration of any spike in
blood sugar and thus, the magnitude and duration of the corresponding insulin release.
Glycemic Load, Glycemic Load, Glycemic Load
If you're aiming to minimize insulin response and support your body's fat-
burning metabolism - there is one concept that stands above all the rest to use when judging the effect of a given food. That concept is, of course, glycemic load. Glycemic load is essentially a measure of how much a given amount of a certain food will increase blood glucose levels after eating.
With the exception of a few specific situations (nutrition during an intense workout is one such exception), you should focus on keeping the glycemic load of any meal relatively low. Keeping the glycemic load low will minimize the amount of insulin released during and after eating. This will in turn
minimize both the amount of carbohydrate from your meal that is stored as fat - and - minimize the time in which fat-burning metabolism is suppressed.
4 Recommendations

All Answers (7)

14th Sep, 2014
Nilesh Kate
Employees’ state Insurance Corporation medical college and hospital kalaburgi
Carbs = Sugar
Sugar in your food generally requires little to no digesting or processing and will be in your bloodstream inside 60 minutes after eating. In response, blood sugar shoots up for a bit before coming back down rapidly a short while later. Other
carbohydrates, referred to as complex carbohydrates, will be sugar in your bloodstream as well eventually. It takes your digestive system a little longer to convert complex carbs into simple sugars, so blood sugar will rise and fall a bit slower depending on a few factors. These include
the type of carbohydrate (how "complex" it is) and how fibrous and/or fatty the food is.
Once in the blood, your metabolism begins to use sugar in a variety of ways. Particularly if you are active or exercising, some of the sugar in your blood will be
used quickly for energy. Glucose and/or fructose are the end-products of all carbohydrate breakdown. These simple sugars enter into either glycolysis (for glucose) or fructolysis (for fructose). In these processes, the metabolism uses the simple sugars to generate the compounds
that, in turn, power all of the body's other metabolic processes. Put more simply, glycolysis and fructolysis convert simple sugars into energy.
(A quick note on fiber: fiber is classified as a type of carbohydrate and is listed on nutrition labels under the
carbohydrate section. Most fiber will pass through the body undigested. The remainder will be digested quite slowly over the course of many hours. Fiber does not have a meaningful effect on blood sugar.)
Insulin: The Storage Hormone
Most of the time, however, sugar is not used immediately but is stored in cells for use later. This is where insulin comes into the equation. Insulin is a protein that acts as a hormone in the digestive process. When a protein is classified as a hormone, it means that it's
presence in the bloodstream triggers a cascade of other related and interdependent processes in the metabolism. Insulin is perhaps the single most important element of nutrient metabolism, and understanding its function is critical for understanding what your body is doing with the food you eat. When
there is more sugar in the bloodstream than the body is immediately using, insulin is released and initiates the storage process. Insulin causes glucose to be absorbed into cells, upon which, it is stored in one of two ways. The primary storage method for glucose is as triglycerides in adipose
(fatty) tissue. The secondary method is as glycogen, essentially a matrix of glucose that is stored in muscle and liver cells for later use as quick energy, primarily in times of exertion.
To summarize, when you eat carbs they are broken down
into sugars by the digestion process. Sugar causes the release of insulin and insulin causes the sugar to be stored, primarily as fat in adipose cells. Particularly when forming a large portion of your caloric intake, carbohydrates are the primary source of any fat your body is storing.
Fueling With Fats
Fat digestion and metabolism happen via completely different pathways than the ones used for carbohydrate metabolism. The first major difference in the digestion of fats relative to
carbohydrates is that the breakdown and absorption is a much slower process. Most fats are broken down slowly in the gut via a series of enzymes called lipases and eventually make their way into the blood stream as free fatty acids. Like sugars, once in the bloodstream free fatty acids can be used for
energy (via the process known as ketogenesis) or stored in adipose (fatty) tissue for later use.
One notable exception to this digestion pathway is medium-chain triglycerides (MCT's). Because they are smaller than other fats, MCT's can pass directly into
the bloodstream without needing digestion in the gut by lipases. These smaller fats are broken down into free fatty acids by lipases in the blood rather than in the gut. While other types of fat take too long to digest and process to be a legitimate alternative to carbohydrate as a primary fuel source, the
quicker availability of MCT's makes them not only a legitimate alternative, but a preferable one. MCT's are also unique among fats in that they can be used by the brain for energy. Other types of fat must go through the long process of being converted into sugars before they can be used by the
brain. Eating primarily other types of fats would leave the brain under-fueled. Once again, MCT's and SCT's not only solve this issue, but offer a superior alternative to carbohydrate. Unsurprisingly, MCT's and SCT's are critical to any diet using fats as a the primary calorie and fuel source.
When your metabolism is using primarily fats as an energy source, you are essentially "training" your metabolism to use fats more often and more efficiently. The metabolic pathways involved in ketogenesis (fat-burning) become more robust, and the body
becomes better at using fat stored in adipose tissue when available sufficient calories are not available from food intake. Fats also don't directly trigger an insulin response, so the body doesn't go into "storage mode" as often when fats are your primary fuel source.
So what are the best sources of MCT's? Coconut oil (and related products) and grass-fed butter are hands-down the top choices. Coconut oil is about 2/3 MCT's by weight. In addition to it's many other benefits coconut oil is the go-to fuel source for many people adhering to this type of high-fat diet. A
few companies isolate the MCT's from coconut oil and sell "MCT oil" by itself. This is a pricy option as an every-day fuel source, but if you're looking to accelerate the fat-burning capacity of a this diet, MCT oil is a powerful tool. Coconut butter is also a great choice, as it is the "meat" of the coconut before
the protein and fiber is pulled out in the process of making coconut oil.
Additionally, grass-fed butter is an excellent source of short-chain fatty acids (as well as many vitamins and Omega-3 fatty acids). These short-chain fatty acids behave in much the same
way as MCT's and can be used for the same purposes. It is important to source only 100% grass-fed (sometimes called "pastured") butter. Conventional butter has a significantly different nutritional profile and is more likely to contain toxins.
Fats vs. Carbs
the metabolism tends to adapt to the types of fuel it is receiving most frequently. If the metabolism is being fueled disproportionately with carbohydrates, the metabolic pathways that use and store carbohydrates will dominate while fat metabolism pathways will
diminish. The reason for this is two-fold. The first reason is that the pathways required to store or use carbohydrates require a set of enzymes unique from those the metabolism uses to process fat. The body is remarkably good at not being wasteful and will decrease production of fat
metabolism enzymes when they are used infrequently. The second reason is that insulin specifically stops the use of fat for energy by inhibiting the release of glucagon, a hormone that increases blood sugar and thus directly competes with insulin.
Because of this "competition" between fat and carbohydrate metabolism pathways, fat will only be used for energy in the absence of insulin. If you're going to train your body to use fat for energy, it becomes critical to minimize both the magnitude and duration of any spike in
blood sugar and thus, the magnitude and duration of the corresponding insulin release.
Glycemic Load, Glycemic Load, Glycemic Load
If you're aiming to minimize insulin response and support your body's fat-
burning metabolism - there is one concept that stands above all the rest to use when judging the effect of a given food. That concept is, of course, glycemic load. Glycemic load is essentially a measure of how much a given amount of a certain food will increase blood glucose levels after eating.
With the exception of a few specific situations (nutrition during an intense workout is one such exception), you should focus on keeping the glycemic load of any meal relatively low. Keeping the glycemic load low will minimize the amount of insulin released during and after eating. This will in turn
minimize both the amount of carbohydrate from your meal that is stored as fat - and - minimize the time in which fat-burning metabolism is suppressed.
4 Recommendations
6th Mar, 2019
Hala Hassan
İstanbul Gelişim Üniversitesi
Many people avoid carbohydrates due to concerns about weight gain, but carbs are needed for the body to function. Carbohydrates are your body’s main energy source and necessary for you to think and remain active. According to MayoClinic.com, carbohydrates should make up 45 to 65 percent of your daily caloric intake. Skimping too much on carbohydrates can cause several health problems.
Lack of Energy
Carbs are your body's preferred source of fuel, so keeping carbs out of your diet can make you feel pretty drained. That's one reason why dieters following a low-carb diet often experience a "keto flu" -- without enough carbs available, dieters feel tired and foggy, at least until their body starts burning more fat for energy. During this time, you might also find your workouts suffer, since your muscles are missing glycogen, a carb that's a quick source of energy.
Hypoglycemia
Hypoglycemia, also known as low blood sugar or low blood glucose, occurs when the glucose levels in the blood drop below normal. While hypoglycemia is often associated with diabetes, it can be caused by a lack of carbohydrates in healthy people. Symptoms of hypoglycemia include tiredness, weakness, light-headedness, confusion and hunger. Carbs are the main source of glucose because they are broken down into simple sugars during digestion and enter the cells with the help of insulin, providing energy. Eating a small amount of carbs will quickly treat hypoglycemia.
Ketosis
Eating less than 130 grams of carbohydrates a day can cause a buildup of ketones, which are partially broken-down fats in the blood. This condition is known as ketosis, according to the Weight-Control Information Network, a service of the National Institute of Diabetes and Digestive and Kidney Diseases. When your body doesn’t have enough glucose for energy, it breaks down stored fat, producing ketones. Mild ketosis can cause mental fatigue, bad breath, nausea and a headache, but severe ketosis can lead to painful swelling of the joints and kidney stones. Aim for 225 to 325 grams of carbohydrates a day to prevent ketosis and other health problems.
Choosing Carbs
Eating too much bread, potatoes, pasta, tortillas and carbohydrate-rich sweets will cause weight gain, but there are many nutritious, weight-friendly carbohydrates. Whole fruits and vegetables are high in vitamins and fiber and low in calories, making them among the healthiest of carbohydrates. Whole grains are another healthy choice – they haven’t been stripped of their outer shell, which contains fiber and important nutrients, such as selenium, potassium, iron and magnesium. MayoClinic.com also recommends low-fat dairy products, beans and legumes as healthy carbohydrate sources. Limit carbs with added sugar to reduce the risk of weight gain, tooth decay and poor nutrition.
Source for answer ;
24th Jun, 2019
Peter Gates
Deakin University
your body is like a hybrid car when it runs out of electricity it changes to petrol(Gas)
Your body only switches to burning fat when it runs out of sugar (carbohydrate)
1st Nov, 2019
Ekim Pekünlü
Ege University
There are essential amino acids
There are essential fatty acids.
But there is neither essential glucose nor essential fructose...So that means....
Prof. Jeff Volek - 'The Art and Science of Low Carb Living: Cardio-Metabolic Benefits and Beyond')
3- https://www.youtube.com/watch?v=BeS_dhM8dsY (Jeff Volek - Keto-Adaptation: Implications for Human Performance)
(Dr. Jason Fung - 'Therapeutic Fasting - Solving the Two-Compartment Problem')
Dr. Stephen Phinney - 'Troubleshooting the Ketogenic Diet for Optimal Weight and Health')
Prof. Tim Noakes - 'LCHF for Elite Athletes')
Ep 10: Prof Tim Noakes says we don’t need carbs or even… vegetables)
1 Recommendation
22nd Aug, 2020
S N Mishra
Maharshi Dayanand University
Body needs both in limited / balance amount to keep in perfect order.

Similar questions and discussions

Scientists Support Ukraine
Discussion
Be the first to reply
  • Ijad MadischIjad Madisch
Like so many, I am shocked and saddened at seeing war break out in Europe. My thoughts – and those of the ResearchGate team – are with the people of Ukraine and everyone affected.
ResearchGate is an international company, whose purpose is to enable scientists across the world to work together openly and collaboratively, regardless of borders or nationality. We have people from over 40 countries on our staff of around 200, and being based in Berlin, we are profoundly aware of the human cost of conflicts, the echoes of which have shaped and scarred our home city. We join with the international community in condemning the actions of the Russian state.
We have been asking ourselves: What can we do?
From today, we will offer free advertising space worth $2.5 million on our network to humanitarian organizations working to respond to the crisis. ResearchGate benefits from over 50 million visitors every month, and we hope this initiative can help raise funds and awareness for those organizations that are having direct impact and need support.
We also want to use our platform to highlight the response from the scientific community. Personally, I have found the messages of support from scientists everywhere to be truly heartfelt, and I would like to highlight some of the community initiatives I’ve seen here:
Additionally, I’m posting here some of the organizations responding to the crisis and actively soliciting donations:
To help gather more support for these initiatives, please consider sharing this post further (you don’t need a ResearchGate account to see it), and I will continue to update it with other initiatives as I find them. You can also click “Recommend” below to help others in your ResearchGate network see it. And if you know of any other community initiatives that we can share here please let us know via this form: https://forms.gle/e37EHouWXFLyhYE8A
-Ijad Madisch, CEO & Co-Founder of ResearchGate
-----
Update 03/07:
This list outlines country-level initiatives from various academic institutions and research organizations, with a focus on programs and sponsorship for Ukrainian researchers:

Related Publications

Article
In vivo body composition measurements are always indirect, based on one or more assumptions concerning the nature of the body components fat mass and fat-free mass including water, protein and bone. Examples of indirect methods, based on assumptions derived from carcass analysis, are densitometry and the measurement of total body water. The other m...
Article
Full-text available
Objective: This study aimed to investigate the effects of different physical exercise protocols on body composition and body density in individuals over years-old in São Carlos (SP), Brazil. Methods: The study consisted of 81 volunteers (51 women and 30 men), who were equally divided into three groups: multicomponent training group, resistance trai...
Article
Sixty Merino lambs were randomly allotted to one of six feeding levels. The feeding levels were ad libitum (control) and 0,82; 0,72; 0,65; 0,55 and 0,45 of ad libitum. The feeding levels were calculated from the average weekly feed intake of the ad libitum group. From 25 to 33 kg live mass, the lambs received restricted feeding except for the contr...
Got a technical question?
Get high-quality answers from experts.