Acizii grasi omega-3: arzator de grasimi inedit

Obsesia de a deveni mai supli este raspandita in randul unui segment mare din populatia generala, dar si in randul sportivilor. Prin reducerea grasimii se cresc peformantele fizice si se imbunatateste aspectul fizic. In acest articol o sa vorbim de rolul acizilor grasi omega-3 in lipoliza si cum suplimentarea cu ei poate imbunatati compozitia corpului (raportul dintre masa adipoasa si cea musculara). 

Studiile arata in mod repetat ca balanta energetica totala este principalul factor care determina slabirea. Este legat de prima lege a termodinamicii, aplicata echilibrului energetic uman: daca arzi mai multe calorii decat mananci, scazi in greutate. Prima lege a termodinamicii este invariabila: cate calorii arzi si cate mananci determina in cele din urma daca slabesti sau nu. 

Dar in ciuda a ceea ce spun unii, nu toate caloriile sunt la fel. De exemplu, este bine documentat faptul ca o parte din caloriile alimentelor sunt arse la digestie, ceea ce este numit efectul termic al alimentelor. Dintre toti macronutrientii, proteinele au cel mai mare efect termic, aproximativ 25-30% din caloriile continute sunt arse la digestie. 6-8% din caloriile continute de carbohidrati sunt arse la digestie si doar 3% din cele continute de grasimi. Asadar, prin alterarea compozitiei dietei, poti influenta partea de ardere a caloriilor din ecuatia termodinamicii. 

Este adevarat si ca diferite tipuri ale aceluiasi nutrient pot avea efecte metabolice diferite. Este adevarat mai ales in cazul grasimilor. 
Grasimile sunt catalogate in doua parti mari: saturate si nesaturate. Cele saturate se numesc asa pentru ca lantul lor de carbon este complet saturat de atomi de hidrogen. Aceste grasimi sunt solide la temperatura camerei si in mare parte inerte din punct de vedere biologic. Daca nu sunt arse imediat pentru energie, sunt depozitate in tesutul adipos.

Grasimile nesaturate, contin una sau mai multe legaturi duble in lanturile lor de carbon. Pentru fiecare legatura dubla se pierd doi atomi de hidrogen din lant. Rezulta o grasime care nu mai este saturata cu atomi de hidrogen (de aici si numele de nesaturata). Grasimile nesaturate sunt catalogate ca mononesaturate (o legatura dubla) si polinesaturate (doua sau mai multe legaturi duble). 

Grasimile polinesaturate au numeroase subtipuri, prima din ele fiind acizii grasi omega-6, avand prima legatura dubla in pozitia 6 a lantului de carbon. Apoi urmeaza acizii grasi omega-3 care au prima legatura dubla in pozitia 3 a lantului de carbon. Toate sunt considerate grasimi esentiale pentru ca nu pot fi produse de propriul corp. 

Omega-3 si slabirea

Dintre toate tipurile de grasimi, omega-3 are cel mai mare efect asupra lipolizei (arderea grasimilor). Principalul mecanism prin care fac asta este prin partitionarea nutrientilor, crescand oxidarea lipidelor si scad sintetizarea lipidelor. Fac asta pe mai multe fronturi:

• Omega-3 cresc fluiditatea membranei celulare. Membranele celulare sunt foarte importante pentru ca regleaza trecerea nutrientilor, hormonilor si chimicalelor in interiorul celulei. Cand membranele celulare sunt mai fluide, devin mai permeabile, permitand substantelor si mesangerilor secundari sa patrunda rapid in citoplasma. Asta are efecte multiple, de la cresterea sintezei proteinelor pana la marirea rezervelor de glicogen muscular, imbunatatirea sensibilitatii la insulina si cresterea productiei de leptina - toti fiind factori cu efecte tangibile asupra slabirii. 
• Omega-3 suprima productia de malonil-CoA. Malonil-CoA este un precursor al sintezei grasimilor. Principala sa metoda de actiune este prin inhibarea activitatii enzimei carnitina palmitoiltransferaza. Aceasta enzima transporta acizii grasi existenti inapoi in mitocondrii, pentru a fi arsi. Prin suprimarea malonil-CoA, nivelurile de carnitina palmitoiltransferaza cresc si astfel creste si fluxul de grasimi arse in mitocondrii. 
• Omega-3 actioneaza ca ligant pentru un receptor hormonal anume, numit recepotrul alfa activat de proliferator peroxisom (PPAR-alfa). PPAR-alfa se gaseste in nucleul celular al multor tesuturi din corp, in special in cele cu un catabolism mare al acizilor grasi precum inima, ficat, rinichi si muschi. Una din functiile sale principale este gestionarea glucozei si acizilor grasi. Mai exact activeaza unele proteine care codifica genele implicate in transportul si oxidarea lipidelor, inclusiv carnitin palmitoiltransferaza hepatica si peroxizomal acil-CoA oxidaza hepatica si musculara. Asadar, omega- 3 creste activitatea acestor enzime care ard grasimi. PPAR creste si nivelurile unei componente care arde grasimi numite proteine de decuplare (UCP), in special UCP-3, care se gaseste mai ales in muschi. UCP-3 este un factior de baza al reglarii ratei metabolice bazale (cate calorii arzi cand stai degeaba). Prin medierea PPAR-alfa, omega-3 creste activitatea UCP-3, crescand capacitatea lipolitica.
• Omega-3 descresc continutul nucleic al proteinei de legare al elementului regulator al sterolilor hepatici (SREBP-1). Aceasta regleaza expresia a numeroase gene hepatice implicate in metabolismul glucozei si biosinteza lipidelor. Suplimentarea cu omega-3 poate scadea cu pana la 85% SREBP-1, suprimand transcriptia genei lipogenice. Prin scaderea numarului de enzime lipogenice, capacitatea corpului de a stoca grasime este diminuata. 

Doze

Este clar ca a consuma suficienti acizi grasi omega-3 ajuta la slabire. Din pacate dozele exacte nu se cunosc. Nu exista nici macar date clare in privinta deficientelor sau suficientelor de omega-3. 

Ce se stie este raportul dintre omega-6 si omega-3. In societatea moderna se consuma omega-6 in exces si prea putin omega-3, raportul fiind de 20-30:1. Asta duce la multe probleme de sanatate si o compozitie a corpului precara. 

Nu exista cercetari in privinta slabirii si raportului omega-6:omega-3, dar pentru sanatate unul de 4:1 este considerat bun. In privinta aspectului fizic si slabirii, probabil ca ideal ar fi un raport de 1:1. Stramosii nostri paleolitici aveau un astfel de raport, si avem aceleasi gene ca ei. Dieta lor era alcatuita exclusiv din carnuri salbatice, peste, leguminoase salbatice, fructe de padure, toate avand omega-3. Se pare ca nu exista efecte nedorite cand consumi cantitati egale de omega-6 si omega-3, si nici cand omega-3 depaseste omega-6. 

Suplimentarea cu omega-3 pentru a slabi

Cand vrei sa slabesti, in primul rand trebuie sa asiguri un deficit caloric, si apoi sa te suplimentezi cu omega-3. Cea mai buna sursa de omega-3 este uleiul de peste. Alege un supliment de calitate, care sa nu fie oxidat, si ia o doza de 5-10 grame pe zi (cate o capsula de 1 grame pentru fiecare 10 kg cantarite - daca ai 80 de kg, iei 8 g de omega-3 pe zi). Cum omega-3 se oxideaaza rapid, ia si un supliment cu antioxidanti.

Si uleiul din ficat de cod este o sursa buna de omega-3 si are si cantitati mari de vitamina D. Dar are un gust cam intepator, ceea ce ii da pe multi inapoi. 

Incearca sa mananci cat mai des peste, si in zilele cand mananci produse marine redu dozele de  suplimente cu omega-3. 

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