Sinteza proteinelor vine din alimentatie?

Studiile au aratat ca atunci cand sunt urmate diete bogate in calorii, majoritatea greutatii acumulate (65%) este grasime, 15% este lichid intracelular, si ce ramane sunt muschi. Se pare ca 25% din cresterea musculara vine din sinteza proteinelor, restul vine din proliferarea celulelor satelit aflate pe tesutul muscular.

Nu se folosesc prima oara ca energie, se folosesc ultima oara bai omule esti turc?

Ce se intampla in cazul unei mese bogate in carbohidrati? Raspuns:acestia sunt oxidati sau transformati in glicogen.Nu sunt transformati in tesut adipos!
Glycogen synthesis versus lipogenesis after a 500 gram carbohydrate meal in man
"Assuming the CHO load to be completely absorbed after 5 hr, and allowing for glucose oxidation calculated from the gas exchange data, the glycogen content of the subject's body tissue had then increased by 408 +/- 19 g. During the 10 hr after the meal, 133 g CHO, 17 g fat and 29 g protein were oxidized, providing respectively 66%, 19%(aproape 20% din energie din oxidarea lipidelor) and 15% of caloric expenditure, and leaving a gain in glycogen stores estimated at 346 +/- 12 g. The data imply that: (1) The capacity for glycogen storage in man in larger than generally believed, and (2) Fat synthesis from CHO will not exceed fat oxidation after one high-carbohydrate meal, even if it is uncommonly large. When a single high-carbohydrate meal is consumed, dietary CHO merely has the effect of reducing the rate of fat oxidation. These findings challenge the common perception that conversion of CHO to fat is an important pathway for the retention of dietary energy and for the accumulation of body fat."
Ce se intampla in cazul unor diete hipercalorice(50% peste mentenanta) in care excesul energetic provine fie din lipide, fie din glucide?
Fat and carbohydrate overfeeding in humans: different effects on energy storage?
"Carbohydrate overfeeding produced progressive increases in carbohydrate oxidation and total energy expenditure resulting in 75-85% of excess energy being stored. Alternatively, fat overfeeding had minimal effects on fat oxidation and total energy expenditure, leading to storage of 90-95% of excess energy. Excess dietary fat leads to greater fat accumulation than does excess dietary carbohydrate, and the difference was greatest early in the overfeeding period."
Metabolsmul carbohidratilor
Nutrient effects:postabsorptive interactions
Dupa o masa bogata in carbohidrati acestia urmeaza 4 posibile cai metabolice:
-sa fie oxidati si sa furnizeze energie
-sa fie stocati sub forma de glicogen
-sa fie transformati in trigliceride
-sa constituie substrat pentru gluconeogeneza
Marea majoritate sunt absorbiti in primele ore.
"Meals usually provide 50-150 g CHO, of which approximately 90% is absorbed within 4 h(Radziuk et al. 1978)"
Peste jumatate sunt stocati sub forma de glicogen.
"In nonobese nondiabetic subjects, after ingestion of a 100 g glucose load, about 40 g glucose are oxidized within 3 h of ingestion, whereas about 50 g are stored as glycogen(Felber et af. 1983), the remaining 10 g being not yet absorbed"
Insulina nu inhiba complet lipoliza.
"During the 3 h period after a 100 g glucose load, glucose, lipid and protein oxidation respectively accounted for 60, 25 and 15% of the energy expenditure (Rousselle et al. 1982)"; adica timp de 3 h de la consumarea a 100 g glucoza, corpul arde 25% din energia sa din grasimi
Insulina stimuleaza oxidarea glucozei.
"Insulin secretion plays a major role after meal ingestion: insulin stimulates glucose oxidation by enhancing glucose transport in insulin sensitive cells, by stimulating glycolysis"
Insulina inhiba lipoliza(dar nu total).
"Insulin also suppresses the activity of the hormonesensitive lipase and, therefore, inhibits lipolysis and lipid oxidation.The inhibition of lipid oxidation parallels the stimulation of glucose oxidation"
"Insulin does not completely suppress glycerol output from adipose tissue, indicating that lipolysis is not entirely inhibited after a meal. By contrast, NEFA(acizi grasi liberi) release is strongly inhibited (Coppack er al. 1990), showing that after a meal the NEFA produced by low rates of lipolysis in adipose tissue are re-esterified within the adipose tissue.
Corpul unui adult este capabil sa stocheze pana la 500 g de glicogen in conditii normale.
"The body’s glycogen reserves are small and are usually maintained at between 250 and 500 g in a 70 kg adult man. A normal maintenance diet provides about 250-300 g CHO/d, which represents 50-100% of the total glycogen stores."
Carbohidratii consumati intr-o dieta tipica(250-300 g/zi) sunt oxidati in intregime pe parcursul unei zile.
"From day to day, changes in the body’s glycogen stores in the postabsorptive state are very small. This indicates that within 24 h there is total oxidation of absorbed dietary CHO."
Carbohidratii nu contribuie semnificativ la formarea tesutului adipos.
"It is to be emphasized that other metabolic pathways for disposal of dietary CHO, such as conversion into TAG(trigliceride) or into nonessential amino acids, are not quantitatively important."
Although the glycogen stores are normally maintained within a relatively narrow range, the capacity for storing large amounts of dietary CHO by conversion to glycogen is relatively large (Acheson et al. 1982, 1984, 1985, 1988)
Ce se intampla in cazul administrarii a 500g maltodextrina(indice glicemic 130)? Aproape jumatate din cantitate este oxidata, peste jumatate este stocata ca glicogen si nu depune nimic sub forma de grasime, ba chiar se mai oxideaza putin din grasime.
"A large load of CHO (500 g dextrinmaltose given as three meals over 5 h) to healthy subjects induces a marked stimulation of CHO oxidation over the 14 h after the first meal (240 g oxidized, 260 g stored; Acheson et al. 1985 Contribution of 500 g naturally labeled 13C dextrin maltose to total carbohydrate utilization and the effect of the antecedent diet, in man). Net lipogenesis occurred at a low rate from 5 to 10 h after the first meal, but this lipid accumulation was offset by a greater rate of lipid oxidation over the next 4 h. The fat balance calculated over 14 h was negative, indicating that the large load of CHO did not induce a gain in fat."
Pe timpul noptii principala sursa de energie sunt grasimile.
In those subjects who were studied throughout the night, carbohydrate utilization declined, fat became the principal energy source and dextrin maltose oxidation could account for almost all of the carbohydrate which was being oxidized. At the end of the 24 h period the cumulative total carbohydrate oxidation was 217 ± 10 g (2 subjects in the high fat group), 300± 13 g (mixed diet group) and 335 ± 7 g (2 subjects in the high carbohydrate group) of which dextrin maltose oxidation had contributed 82%, 70% and 73% respectively.
Dar cand se adminitreaza 500 g maltodextrina persoanelor obeze versus non obeze?
Carbohydrate metabolism and de novo lipogenesis in human obesity
"During the 14 h, the lean subjects oxidized 28 ± 4 g protein and 15 ± 4 g of fat. Of the 15 g of fat oxidized, 4 ± 7 g were restored by synthesis from carbohydrate, resulting in an overall balance of -11±4g.In the obese, 29 ± 3 g of protein were oxidized during the 14 h. The total amount of fat oxidized was similar to that of the lean controls(19 ± 5 g/l4 h) and was counter-balanced by a gain of 5 ± 3 g of fat during the periods in which de novo synthesis of fat exceeded concomitant fat oxidation. This resulted in an overall fat balance of -14 ± 8 g/ 14 h."
"Evidence that dietary fat, rather than fat synthesis from carbohydrate, provides the precursors for adipose tissue triglycerides should help to alleviate the commonly held fear among weight-conscious individuals that carbohydrate turns into fat. This erroneous belief may lead these individuals to avoid foods known to contain primarily carbohydrates infavor of foods known for their low-carbohydrate content (ie, high-protein items). Such a pattern of food selection would be unfortunate, indeed, because it promotes the consumption of foods with a high-fat content, which is much more likely to sustain positive fat balance than dietary carbohydrate."

Dar ce se intampla cand o persoana consuma 740 g de carbohidrati(cu 60 g de lipide si 100 g de proteine)? Din nou corpul stocheaza aproape jumatate din ei si arde restul.
"In another study, after 3 day on a hypoenergetic low CHO diet to deplete glycogen stores, a very large amount (740 g) of dietary CHO (with 60 g fat and 100 g protein), consumed during the 4th day by healthy young human subjects, induced an increase of 340 g in the glycogen store, without initiating de novo lipid synthesis at rates exceeding concomitant fat oxidation (Acheson et al. 1988). In this study, 400 g CHO/d were oxidized. These findings show that high amounts of dietary CHO can be accommodated by inducing a stimulation of CHO oxidation and an increase in glycogen stores. The important point is that there was no gain of fat by de novo lipogenesis, as a small amount of net lipid oxidation was observed.
Acheson et al. (1988) showed in young men that glycogen stores must increase by about 500 g before net conversion of CHO into fat occurs. When the glycogen stores become saturated, the only way of disposing of additional excess CHO intake is by fat synthesis. This phenomenon can be demonstrated under artificial conditions of overfeeding. In everyday life, a high intake of CHO elicits an increase of satiety, and subsequently food intake is decreased(Blundell et al. 1993). These results support the concept that dietary CHO does not increase an individual’s fat content by de novo lipogenesis under normal conditions."
Hellerstein et al. (1991) showed in humans that the fraction of very-low-density-lipoprotein-palmitate derived from de novo lipogenesis was only 0.9% in the fasted state and 2% in the fed state after a high-CHO breakfast. These results support the concept that de novo lipogenesis is not an important pathway in humans."
Ce se intampla in cazul unor diete high carb hipercalorice pe o perioada mai lunga de timp?
Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man
In acest experiment 3 tineri au consumat o dieta hipocalorica(1600 cal) high fat(75%, p=15%, c=10%) timp de 3 zile, concomitent cu exercitii fizice pentru golirea rezervelor de glicogen.Au urmat apoi o dieta high carb(c=86%, p=11, L=3%) si hipercalorica(3500 calorii crescute treptat pana la 5000 de cal) timp de 7 zile, apoi 2 zile de high protein si hipocalorica(600cal) si inca 2 zile de high fat.
In peroada high carb subiectii s-au ingrasat 4.6 kg, in cele 2 zile de dieta hipocalorica au slabit 4.4 si la final au revenit la greutatea initiala.
"After the 7 d of overfeeding the high-carbohydrate, low-fat diet (day 10), body weight had increased by 4.6 ± 1.3 kg (ie, 5.6, 4.9, and 3.2 kg). During the 2 d on the restricted high-protein, low-energy diet (600 kcal/d) 4.4 ± 0.9 kg were lost. Two days later, body weights were the same as at the start of the overfeeding phase of the experiment"
Pe perioada dietei high carb metabolismul subiectilor a crescut cu 35%(de la 2400 cal la peste 3200 cal), corpul reusind partial sa disipeze excesul de calorii.De unde provine aceasta crestere?
"Carbohydrate stored as glycogen requires the expenditure of 2 mol ATP per glucose moiety converted into glycogen plus 0.5 mol for the cost of active transport in the gut and other phenomena, such as digestive enzyme synthesis and gut motility. Because glucose oxidation yields 36 mol ATP, the cost of glycogen synthesis consumes 2.5/36 or 7% ofthe glucose stored as glycogen. The transformation of glycogen into fatty acids, the subsequent esterification before export from the liver, and then triglyceride storage in adipose tissue consume additional ATP, estimated at 18%. Thus ~25% of the energy of the glucose channelled into de novo lipogemesis can be expected to be needed for this process.Of the energy consumed in excess of maintenance energy, 75% was retained and 25% dissipated."
Cand incepe corpul sa transforme in lipide carbohidratii? Doar cand exista exces cronic de glucide si rezervele de glicogen sunt saturate.
"Our data suggest that glycogen stores must increase by 500 g before appreciable de novo lipogenesis begins. Provided that massive amounts of carbohydrate continue to be ingested, the glycogen stores become saturated so that the only way of disposing of additional excess carbohydrate is by fat synthesis in addition to maximal use of glucose for energy generation."
"From these data it would seem that the glycogen stores can maximally accommodate 800-900 g of carbohydrate and perhaps as much as 1-1.1 kg in trained athletes. These results are among the highest glycogen storage values reported in the literature."
Ce reprezinta cele 4.6 kg acumulate?
-2.1-3.5 kg glicogen+apa
-650 g tesut muscular
-1.1 kg tesut adipos din care 600g provenit din excesul de glucide(de novo lipogenesis) si 500g din lipidele din dieta.
Assuming that glycogen is stored with two to four times its weight of water, ~2.1-3.5 kg of the change in body weight can be accounted for. Cumulative gains of body fat by de novo lipogenesis and from that which was provided in the diet amounted to 1.1 kg fat. Thus with the 665 g increase in lean body mass indicated by a gain of 133 g protein, we can account for the 4.6 kg increase in body weight.
"During the 6 d during which lipid synthesis exceeded fat oxidation, net de novo lipogenesis amounted to a total of 580 g. Because in addition to de novo lipogenesis some fat was provided in the diet (85 g/d), the overall fat gain was ~1.1 kg"
"Finally, our findings indicate that the body’s glycogen stores are far from completely filled under normal ad libitum conditions."
Concluzia este ca toata ingrijorare starnita de autori fara expertiza in domeniu si care s-au avantat in concluzii riscante si nesustinute de litearatura stiintifica sunt complet nejustificate.Desi posibil ca excesul de glucide sa fie convertit in lipide, intr-o dieta normala acest lucru este improbabil.Sunt necesare 3 conditii:
-dieta hipercalorica
-consum exagerat de glucide
-supraconsum cronic(2-3 zile nu sunt suficiente)
De remarcat usurinta cu care s-au depus lipidele din dieta desi procentual au reprezentat doar 3% din totalul caloriilor. Avand in vedere ca lipidele intr-o dieta normala ajung pe la 30-40%, rezulta ca intr-o dieta mixta hipercalorica adevarata problema o reprezinta lipidele.Ele contribuie intr-o maniera covarsitoare la formarea tesutului adipos.In prezenta atat a glucidelor cat si a lipidelor corpul foloseste prioritar glucidele si lipidele se depun.Stiintific vorbind dietele low fat au o justificare in metabolismul uman.Insa ele n-au fost urmate decat rar la nivelul populatiei.Din acest motiv(si din altele) tind sa nu mai fie recomandate in ultima vreme si nu din cauza ca fiziologic ele n-ar functiona.Trebuie remarcat totusi ca intr-o dieta mixta eucalorica(in balanta calorica) atat lipidele cat si carbohidratii sunt oxidati si nu se depun sub forma de tesut adipos.

Nu sunt obligat sa cred in ce crezi tu, ti-am explicat frumos ca proteinele se convetesc in grasimi daca manci multe, daca 10 kg de carne pe zi sa numi spui ca nu o sa ingrasi deloc

Nu exista cuvantul carbohidrati in medicina, pentru inceput. Exista glucide. Care ti-am spus acum 20 de minute ca se transforma in glicogen. I give up man, esti turc citeste primul raspuns si lamureste-te, ma doare capul cu tine sa iti explic acelasi lucru de 10 mii de ori. Proteinele nu se transforma in grasime! Retine asta!

Daca manci 2 kg de carne pe zi ce se intampla? slabesti nu?

Although excess calories from fat, protein and even carbohydrates get stored as fat, the body prefers to use protein and carbs elsewhere. Protein is the last resource tapped when your body needs energy for everyday activities or exercise. Likewise, protein resists conversion to fat because your body uses this nutrient for other functions, such as repairing muscle tissue following exercise, building muscle and delivering oxygen to working muscles. Taking in more calories than you need, however, can result in excess body fat, regardless of your primary source of calories.

http://www.livestrong.com/......ter-eaten/

Ba nu e cred eu, esti deja imbecil. Sunt student la medicina, am facut 1 an jumate de biochimie si vii cu niste opinii babesti si articole pseudo-stiintifice care sustin acelasi lucru pe care ti-l zic si eu.

Alo eu nu team jignit, nimeni nu e obligat sa creada ce crezi tu, manca tu 2 kg de carne de porc timp de o luna mai discutam, ti-am explicat ca cand manci ceva o partea se foloseste ca energie, celule etc si restul se pastreaza, nu esti obligat sa crezi daca esti asa nu ai ce cauta acolo trebuie sa iubesti stiinta nu sa ai minte inchisa,nici un studiu nu a demonstrat ca daca subiecti au mancat o dieta bogata in proteine, carbo, grasimi nu sau ingrasat la fel, atunci am manca carne non stop si am fi slabi, si eu apreciez proteinele si eu manc zilnic dar putine ca ingrasa, totul ingrasa

Http://www.mediafire.com/......+obese.pdf

studiul a cuprins 3 grupe de pacienti obezi, care au consumat diete high fat si high carb insa pe perioade mai lungi decat in studiul lui Kekwick si Pawan. Daca studiul acestora a durat 7-10 zile, studiul de fata a durat pana la 4 luni.
Prima grupa a consumat alternativ la cate 18 zile o dieta high fat 62% grasimi, urmata de o dieta high carb 78% glucide. Ambele diete aveau 800 Cal.
A doua grupa a consumat la intervale de 24 de zile o dieta high fat 70% grasime, urmata de o dieta high carb 75% glucide. Ambele diete au avut 1000 de Cal.
A treia grupa a consumat timp de 24 de zile alternativ o dieta high fat 86% grasimi, urmata de o dieta high carb 91% glucide. Ambele diete au avut 1000 de Cal.

Toate dietele au mentinut proteinele la acelasi nivel intre cele 2 diete si dietele au fost alternate pana la 4 luni. Rezultatul? Toti pacientii au pierdut in greutate in mod similar indiferent de dieta. Dpdv al unui adept low carb acest lucru pare de neconceput: cum adica sa consumi 90% din calorii sub forma de carbohidrati si sa slabesti la fel ca atunci cand consumi o dieta cu 86% grasimi? Da, pentru ca slabirea nu are de-a face cu carbohidratii sau cu insulina sau cu toate erorile stiintifice debitate de Taubes. Slabirea are de-a face cu deficitul caloric. Ai deficit caloric, slabesti, n-ai deficit caloric, nu slabesti. Si asta demonstreaza toate studiile metabolice din ultimii 60 de ani, adica pe o dieta high fat nu se slabeste mai mult decat pe o dieta high carb, in conditiile unor diete egale caloric.

ca student uitate la studiu

Http://www.mediafire.com/file/10ddabd3pqmnzz3/Fatty+foods+and+obesity.pdf
2 pacienti obezi au consumat o dieta high fat de 1500 Cal in care proportia grasimi - proteine a fost de 5:1 si carbohidratii sub 25 de grame. Au pierdut din greutate abrupt dupa care la 5-7 zile greutatea s-a stabilizat. In urmatoarele 9 zile au consumat tot o dieta high fat dar de 2000 de Cal. Unul din pacienti a ramas stabil, iar celalat a acumulat 1 kg.
Un al treilea pacient a consumat o dieta high fat de 2000 Cal dupa o dieta mixta si timp de 5 zile a pierdut in greutate dupa care s-a stabilizat.
Alti 4 pacienti au consumat o dieta high fat de 2000 de Cal timp de 13 zile. In primele 7 zile au pirdut in greutate dupa care s-au stablizat.

Apoi toti pacientii au consumat o dieta high carb de 1200 Cal in ultimele 5-7 zile ale experimentului. In aceasta perioada greutatea lor a ramas stabila in ciuda scaderii caloriilor. Insa de data asta cercetatorii au fost precauti si au masurat rata metabolica a pacientilor. Au descoperit ca metabolismul lor cheltuia mai multa energie decat era furnizata prin dieta, deci in aceasta perioada deficitul era acoperit din tesutul gras, in ciuda mentinerii greutatii. De ce greutatea nu a scazut? Pentru ca pe dietele high carb in primele zile are loc o retentie de apa care mascheaza pierderea in fapt a greutatii corporale datorata oxidarii grasimilor, asa cum pe o dieta high fat in primele zile se pierde de fapt glicogenul si apa aferenta. In cuvintele autorilor:

Lasa-ma cu sunt student cu toti stim cum iesiti din facultate si ce doctori avem in tara, ca esti student nu inseamna ca sti totul, intreaba un doctor daca carnea nu ingrasa sau un profesor sa vedem ce o sasi spuna

Ce doctori avem in tara? Da, avem aia de pe la facultatile slabe care nu pleaca afara pentru ca nu sunt capabili, cei buni, care sunt si la fara taxa, pleaca primii din tara. E bine ca tu care esti paralel cu medicina vii si iti dai cu parerea, iar cand cineva care cat de cat este in domeniu si incearca sa iti explice, spui ca nu, ca tu stii mai bine. Cumpara o carte de biochimie, mergi la metabolismul proteic si ai acolo toate informatiile.

Ba nea Gica, ce studii stiintifice vrei? Deschide o carte si afli tot ce vrei. Carnea de porc nu contine doar proteine, te-ai uitat vreodata cate proteine are? E plina si de lipide. Nici macar nu stii din ce e formata o celula, dar tu vii si iti dai cu parerea. Du-te acas'!

Sunteti zero vin straini si va lecti de viata, multi habar nu aveti de medicina cand terminati facultatea

Omule tiam trimis si studii tu tot degeaba, eu ma asteptam sa ai o minte deschisa ca na esti viitor doctor cu mintea asta nu ai cauta afara din Romania

Ai o boala, ceva?

Nu,de ce?

Omule citeste studiul dieta bogata in proteine vs dieta bogata in carbo ambi subiecti au slabit la fel, da contine si grasimi desigur dar si proteine care daca nu sunt metabolizate vor fi folosite ca tesut adios

Strainii? Vrei sa vorbim despre arabii care termina medicina aici? Sunt colegi cu mine, isi cumpara fiecare examen aproape, nu stiu absolut nimic, termina facultatea pe bani. Noi pana una alta invatam pe bune. Nu mi-ai trimis niciun studiu, ce pana mea imi pasa mie ca ala mananca carne de taur sau nu, ceea ce iti zic de 2 ore deja e ca proteinele nu sunt grasimi. Aia e tot! La ce mai pui intrebari daca crezi ca le stii pe toate, in conditiile in care tu nici nu esti capabil sa scrii 2 cuvinte corect in limba romana? Mergi inapoi la scoala primara, dupa poti sa vii si sa-mi spui ca sunt zero.

Si eu isi spun ca proteinele nu sunt grasimi dar vad ca nu intelegi,proteinele sunt alt macronutrient, nu minti ca am spus ca proteinele sunt grasimi, eu am spus ca si proteinele se pot converti in grasimi daca manci mai mult decat consumi, de exemplu daca manci 1, 2kg de carne de porc pe zi te vei ingrasa si nu doar din cauza lipidelor

Te rog sa mananci tu 1 kg de carne de porc pe zi, doar atat si ma anunti ce rezultate ai.

Daca tot afirmi ceva de ce nu prezinti un studiu sau vreo dovada stiintifica cum ca proteinele se elimina, eu ti-am dat doua studii

Imi pierd timpul cu tine pa

Proteins
Proteins consist of units called amino acids, strung together in complex formations. Because proteins are complex molecules, the body takes longer to break them down. As a result, they are a much slower and longer-lasting source of energy than carbohydrates.

There are 20 amino acids. The body synthesizes some of them from components within the body, but it cannot synthesize 9 of the amino acids—called essential amino acids. They must be consumed in the diet. Everyone needs 8 of these amino acids: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Infants also need a 9th one, histidine.

The percentage of protein the body can use to synthesize essential amino acids varies from protein to protein. The body can use 100% of the protein in egg and a high percentage of the proteins in milk and meats. The body can use a little less than half of the protein in most vegetables and cereals.

The body needs protein to maintain and replace tissues and to function and grow. Protein is not usually used for energy. However, if the body is not getting enough calories from other nutrients or from the fat stored in the body, protein is used for energy. If more protein is consumed than is needed, the body breaks the protein down and stores its components as fat.

The body contains large amounts of protein. Protein, the main building block in the body, is the primary component of most cells. For example, muscle, connective tissues, and skin are all built of protein.

Adults need to eat about 60 grams of protein per day (0.8 grams per kilogram of weight or 10 to 15% of total calories). Adults who are trying to build muscle need slightly more. Children also need more because they are growing. People who are limiting calories to lose weight typically need a higher amount of protein to prevent loss of muscle while they are losing weight.

http://www.msdmanuals.com/......,-and-fats

Dupa ce am slabit acum sa maresc nr caloriilor nici vorba