TNF and vitamin B12 deficiency: Considering that (i) obesity is a known chronic low-grade inflammatory condition (48) and (ii) our results show proinflammatory adipocytokines, such as TNF-α and IL-6, are significantly increased as early as 4 weeks of feeding vitamin B12 deficient diet, suggesting that severe vitamin B12 deficiency in early life may increase the animal’s vulnerability to obesity.