Those arguments (food digestion speed, “rotting”, and intestine length) are propounded and spread by the literature of the Hare Krishna’s – a strongly vegetarian-oriented faith. This fact doesn’t make the arguments wrong in and of itself, but the actual scientific foundation for the arguments is lacking.

First, they assume that creatures are either plant eaters or flesh eaters. Humans, apes and many other animals are omnivores – we can and do eat both plants and animals.

Second, both plant and animal tissues are digested just fine in the intestines of omnivores (and rot rather nicely outside of it). Their use of the term “rot” is a scare-word, designed to elicit an emotional response, not a scientific one.

Third, meat doesn’t linger in the intestines for days nor become toxic any more than vegetable matter does. One can get food poisoning from contaminated vegetables as well as meats. The only “linger” exception occurs in those prone to constipation – and if you are getting enough fiber, the “lingering” disappears.

Obesity is a major threat – for cancer, diabetes, heart disease, stroke, etc. The question for me becomes one of the balancing of risks – even if meat bumps up the colon cancer risk, to me, the decline of the other risks does more to offset other risks. Interestingly, studies that have shown increased colon cancer for meat-eaters show little difference in mortality, suggesting that the meat-related cancers are more benign and treatable than other types.

Also, there is a quality of life issue here as well – getting and being thinner is improving my life in many ways. If it came down to it, I’d rather have 20 more good years than 30 more miserable ones.