ayurved ke anusar svasth manav sharir men ‘vat’ (vayu), ‘pitta’ (agni) aur ‘kaf’ (jal) tatva saman anupat men vidyaman rahte hain. inka santulan bigrne se rogon ki utpatti hoti hai. sarvapratham vayu tatva ka santulan bigrta hai aur uske bad pitt v kaf tatva bhi asantulit ho jate hain. hamare sharir men ye tinon tatva alg-alag samay prabhavi hote hain kaf (jal) tatva subah ke samay pitt (agni) tatva dopahar ke samay tatha vat (vayu) tatva aprahn ya sandhya men prabhavi rahte hain. kaf tatva ratri men kie gae bhojan ki ashuddhiyon ko subah dur karta hai.
kaf tatva ki kriya subah 6 baje se aranbh hokar 8 baje apni charam sima par pahunchti hai aur 10 baje tak samapt ho jati hai. atah ayurved men suryoday se tin ghante tak thos ahar karna nishedh hai. usha pan (subah uthakar jal pina) aur bad men dudh, matthe aur falon ke ras ka sevan labhdayak mana gaya hai.
10 baje se dopahar 2 baje tak ‘pitta’ (agni) tatva pradhan hone ke karan is bich kiya gaya bhojan asani se pach jata hai aur sharir ko shakti pradan karta hai. 2 baje bad kiya gaya bhojan vayu tatva barhata hai aur barhti umra men uchch raktachap aur anya vikaron ka karan banta hai. dusri bar bhojan ratri men 8 baje tak kar lena chahie jisse vah dhire-dhire subah tak pach jae. ratri men halka bhojan hi karna chahie. jab tak avashyak n ho, khana khane ke do ghante bad tak pani nahin pina chahie kyonki isse jathragni thandi hoti hai aur vayu tatva asantulit hota hai
jisse rog utpann hote hain. jyotish shastra men pitt (agni) tatva ke karak surya v mangal hain. kaf (jal) tatva ke karak chandra, budh v shukra hain. vat (vayu) tatva ke karak shani aur guru hain. grah apne samay par in tatvon ko prabhavit karte hain. matbhedanusar budh grah tridhatu vat, pitt, kaf tinon ka karak hai aur guru pitt aur kaf ka karak hai. rahu aur ketu udrvayu ko asantulit karke rog dete hain. subah 6 baje se 10 baje tak chandrama, shukra ya budh ki shakti, jiska kaf tatva par adhipatya hota hai, sakriya hoti hai.
somvar, shukravar v budhvar ko yah shakti subah ke samay shatapratishat karya karti hai, kyonki din ka pratham hora var adhipti grah ka hota hai. 10 baje se 2 baje tak ka samay surya aur mangal ki agni shakti ke adhin hota hai, jo bhojan ki pachan kriya men sahayak hota hai. atah 10 se 12 baje tak bhojan karna labhdayak hota hai. uske bad agni tatva men kami ane lagti hai aur 2 baje samapt ho jati hai.
is karan bhojan karne ka samay madhya divas tak uchit hota hai. do baje se aranbh hokar 4 baje sayankal tak vayu tatva ki shakti uchch rahti hai aur 6 baje tak samapt ho jati hai. atah sandhyakal bhojan karne se vat (vayu) tatva men asantulan paida hota hai tatha brihaspati (charbi, gais, daybitij, adi) aur shani (snayu, kabj, adi) sanbandhi rogon ki sanbhavna barhti hai. atah shastranusar manushyon ko bhojan svachch, shant aur prasannachitt hokar karna chahie tatha adhik bhojan nahin karna chahie. din men keval do bar hi bhojan karna chahie.