I personally never understood why we didn't have a SDA type of policy on health.
*** it-1 p. 964 Glutton *** (the same is said in the Aid book as well)
GLUTTON: A selfish, greedy person given to excessive indulgence, especially voracious eating. Gluttony in any form is diametrically opposed to Bible precepts and principles.
Under the Mosaic Law, parents of an incorrigible son who was a glutton and a drunkard were to bring him to the older men of the city, who would have him stoned to death. (De 21:18-21) As a warning to others, the Proverbs condemned even association with gluttons: "One having companionship with gluttons humiliates his father." "Do not come to be among heavy drinkers of wine, among those who are gluttonous eaters of flesh. For a drunkard and a glutton will come to poverty, and drowsiness will clothe one with mere rags." (Pr 28:7; 23:20, 21) The Hebrew term here used for "glutton" and ‘gluttonous eater’ is zoh·lel´. The basic sense of the word is possibly "be lavish," that is, wasteful, prodigal.—Compare De 21:20, ftn.
In an effort to discredit Jesus Christ, one of the charges of slander hurled at him by his opponents was: "Look! A man gluttonous and given to drinking wine." Jesus simply refuted the false charge by saying, "Wisdom is proved righteous by its works" or "by all its children." (Mt 11:19; Lu 7:34, 35) In other words, Jesus was saying, ‘Look at my righteous works and conduct and you will know the charge is false.’
Gluttony certainly has no place in the Christian congregation, and the apostle Paul wanted to make sure it would not creep in. So, when leaving Titus in Crete to look after the young Christian organization there, he reminded Titus what one of Crete’s own prophets (thought to have been Epimenides, a Cretan poet of the sixth century B.C.E.), had said: "Cretans are always liars, injurious wild beasts, unemployed gluttons [literally, bellies]." Therefore, the overseers whom Titus would appoint, Paul said, should be men free of all such accusations, men who were not drunkards or greedy and who had good self-control.—Tit 1:5-12.
Although not listed separately as a ‘work of the flesh,’ gluttony often accompanies drunken bouts and revelries, and it is certainly included in the comprehensive expression "things like these," the practicers of which "will not inherit God’s kingdom." (Ga 5:19, 21) Moderation in eating habits, as in all other activities, is a Christian virtue.—1Ti 3:2, 11.
I guess the GB assume that with only low paying jobs JWs naturally stay slim between little food and lots of walking during FS....