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Plant Based Nutrition and Fasting

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2 hours ago, Bonobojt said:

does anyone here any issues digesting certain foods ? even if that food is considered healthy


I think I have a problem digesting starchy root vegetables like Potatoes, I have been eaten potatoes a lot recently, something I don't normally do in my life, I've been eaten it with wholemeal bread and beans. My digestion hasn't been good at all ever since I included potatoes in my diet, bloated and constipated even though I'm eating whole foods plant based, lots of fiber etc..


I've been eating bread and beans, oatmeal, fruit etc for years with no problems, so I'm sure its the potato.


though my gut health isn't perfect since I've been on antibiotics way too many times and I got a parasite infection in April which I needed antibiotics to treat. so maybe the poor digestion is a consequence of the parasite infection and/or antibiotic use history. 

I don't have a problem with them myself but I know some people can have an allergic reaction to potatoes.  You might be one.  Supposedly for some people, the body mistakes certain proteins in potatoes as harmful and the body reacts by stimulating the immune system to deal with it.  Histamines are released and that could account for your symptoms.

Edited by Kohsamida

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Starvation Response in Nutritional Fasting:  I thought it would be interesting to provide another slightly more detailed overview of what really happens to your body during a water fast.  It's probably not of interest to most people but for those who are curious, it's worth a read, even if it is a long one.


The reason I am posting this is simply because there is so much "myth" involved in what is really happening inside you body during a water fast, whether it's one  of short duration or longer.  Everything I am including is scientific fact; nothing is pseudo-science, conjecture or hypothesis unless it is specifically cited as such.


So, "nutritional fasting" is just another term for eliciting a "starvation response", or rather, a set of adaptive biochemical and physiological changes that alter metabolism in response to lack of food.  


The energetic requirements of a body are composed of the basal metabolic rate and the physical activity level. This caloric requirement can be met with protein, fat, carbohydrates, alcohol, or a mixture of those. Glucose is the general metabolic fuel, and can be metabolized by any cell. Fructose and some other nutrients can only be metabolized in the liver, where their metabolites transform into either glucose stored as glycogen in the liver and in muscles, or into fatty acids stored in adipose tissue.


Because of the blood–brain barrier, getting nutrients to the human brain is especially dependent on molecules that can pass this barrier. The brain itself consumes about 18% of the basal metabolic rate: on a total intake of 1800 kcal/day, this equates to 324 kcal, or about 80 g of glucose. About 25% of total body glucose consumption occurs in the brain.


Glucose can be obtained directly from dietary sugars and by the breakdown of other carbohydrates. In the absence of dietary sugars and carbohydrates, glucose is obtained from the breakdown of stored glycogen. Glycogen is a readily-accessible storage form of glucose, stored in notable quantities in the liver and in small quantities in the muscles.


When the glycogen reserve is depleted, glucose can be obtained from the breakdown of fats from adipose tissue. Fats are broken down into glycerol and free fatty acids, with the glycerol being utilized in the liver as a substrate for gluconeogenesis.


When even glycerol reserves are depleted, or sooner, the liver starts producing ketone bodies. Ketone bodies are short-chain derivatives of fatty acids, which, since they can cross the blood–brain barrier, can be used by the brain as an alternative metabolic fuel. Fatty acids can be used directly as an energy source by most tissues in the body.


After the exhaustion of the glycogen reserve, and for the next 2–3 days, fatty acids are the principal metabolic fuel. At first, the brain continues to use glucose, because, if a non-brain tissue is using fatty acids as its metabolic fuel, the use of glucose in the same tissue is switched off. Thus, when fatty acids are being broken down for energy, all of the remaining glucose is made available for use by the brain.


After 2 or 3 days of fasting, the liver begins to synthesize ketone bodies from precursors obtained from fatty acid breakdown. The brain uses these ketone bodies as fuel, thus cutting its requirement for glucose. After fasting for 3 days, the brain gets 30% of its energy from ketone bodies. After 4 days, this goes up to 75%.


Thus, the production of ketone bodies cuts the brain's glucose requirement from 80 g per day to about 30 g per day. Of the remaining 30 g requirement, 20 g per day can be produced by the liver from glycerol (itself a product of fat breakdown). This still leaves a deficit of about 10 g of glucose per day that must come from some other source. This other source is the body's own proteins.


After several days of fasting, all cells in the body begin to break down protein. This releases amino acids into the bloodstream, which can be converted into glucose by the liver. Since much of our muscle mass is protein, this phenomenon is responsible for the wasting away of muscle mass seen in starvation, but their is a caveat to this!


The body can selectively decide which cells break down protein and which do not. About 2–3 g of protein must be broken down to synthesize 1 g of glucose; about 20–30 g of protein is broken down each day to make 10 g of glucose to keep the brain alive. However, to conserve protein, this number may decrease the longer the duration of fasting is.


What's more, the body is also selective about which proteins are broken down.  Through the process of autophagy, damaged or dysfunctioning intracellular proteins are favored as a fuel source over essential proteins such as those found in the heart and striated muscle as long as the body's fat stores can provide the bulk of fuel required.


Furthermore, The human starvation response is unique among animals in that human brains do not require the ingestion of glucose to function.  During starvation, less than half the energy used by the brain comes from metabolized glucose. Because the human brain can use ketone bodies as major fuel sources, the body is not forced to break down skeletal muscles at a high rate, thereby maintaining both cognitive function and mobility for up to several weeks. This response is extremely important in human evolution and allowed for humans to continue to find food effectively even in the face of prolonged starvation.


Consider this chart which shows the oxidation rate of protein during extended fasting.  Note how proteins are spared as fat metabolism rapidly ramps up. (from Dr. Kevin Hall's of the NIH in his textbook, “Comparative Physiology of Fasting, Starvation, and Food Limitation”):


snapshot_ 2018-07-16 at 12.57.35 PM.jpg

Initially during a fast, the level of insulin in circulation drops and the levels of glucagon, epinephrine and norepinephrine rise.  At this time, there is an up-regulation of glycogenolysis, gluconeogenesis, lipolysis, and ketogenesis. The body’s glycogen stores are consumed in about 24 hours. In a normal 70 kg adult, only about 8,000 kilojoules of glycogen are stored in the body (mostly in the striated muscles).The body also engages in gluconeogenesis to convert glycerol and glucogenic amino acids into glucose for metabolism. Another adaptation is the Cori cycle, which involves shuttling lipid-derived energy in glucose to peripheral glycolytic tissues, which in turn send the lactate back to the liver for resynthesis to glucose. Because of these processes, blood glucose levels remain relatively stable during prolonged starvation.


However, the main source of energy during prolonged starvation is derived from triglycerides. Compared to the 8,000 kilojoules of stored glycogen, lipid fuels are much richer in energy content, and a 70 kg adult stores over 400,000 kilojoules of triglycerides (mostly in adipose tissue).   Triglycerides are broken down to fatty acids via lipolysis. Epinephrine precipitates lipolysis by activating protein kinase A, which phosphorylates hormone sensitive lipase (HSL) and perilipin. These enzymes, along with CGI-58 and adipose triglyceride lipase (ATGL), complex at the surface of lipid droplets. The concerted action of ATGL and HSL liberates the first two fatty acids. Cellular monoacylglycerol lipase (MGL), liberates the final fatty acid. The remaining glycerol enters gluconeogenesis.


Fatty acids by themselves cannot be used as a direct fuel source. They must first undergo beta oxidation in the mitochondria (mostly of skeletal muscle, cardiac muscle, and liver cells). Fatty acids are transported into the mitochondria as an acyl-carnitine via the action of the enzyme CAT-1. This step controls the metabolic flux of beta oxidation. The resulting acetyl-CoA enters the TCA cycle and undergoes oxidative phosphorylation to produce ATP. The body invests some of this ATP in gluconeogenesis to produce more glucose.


Triglycerides and long-chain fatty acids are too hydrophobic to cross into brain cells, so the liver must convert them into short-chain fatty acids and ketone bodiesthrough ketogenesis. The resulting ketone bodies, acetoacetate and β-hydroxybutyrate, are amphipathic and can be transported into the brain (and muscles) and broken down into acetyl-CoA for use in the TCA cycle. Acetoacetate breaks down spontaneously into acetone, and the acetone is released through the urine and lungs to produce the “acetone breath” that accompanies prolonged fasting. The brain also uses glucose during starvation, but most of the body’s glucose is allocated to the skeletal muscles and red blood cells. The cost of the brain using too much glucose is muscle loss. If the brain and muscles relied entirely on glucose, the body would lose 50% of its nitrogen content in 8–10 days.


Edited by Kohsamida

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BANGKOK 16 July 2018 15:41