You read that right: the overly thin and the overly thick are both tending towards shorter and less healthy lives with greater chances of an early death. It even appears that when faced with being overweight or underweight, being overweight carries the greater advantage. Although being slightly overweight or normal had already been associated with increased survival compared to both obese or underweight people, a new study indicates that being slightly overweight (which I’ll call chubby for ease) is related to higher levels of energy in the brain and thus a lower risk of dementia.
The new study, from Washington University School of Medicine in St. Louis, links adequate adipose fat reserves and the ability to translate these into increased SIRT1 (and thus energy carrier NAD+) with increased physical activity and neural activity. Mutants mice that were deficient in this ability through an NAMPT knock-out (where the gene is removed) displayed significantly less neural activity, and knocking the gene back in returned the mice to normal functionality. The study shows that there exists an interplay between neural activity/health, and sufficient adipose fatty tissue.
Although the exact signalling system and the “optimal” amount of fatty tissue have not been defined, it is clear that interplay between the brain and fatty tissue are important. The results for Corrada et al’s 2006 study suggest having available fatty tissue may be important to more than neural activity, but likely also proper physical functioning. After all, how else can we explain the consistently higher survival odds for even the obese relative to the underweight in literally every age group in Corrada’s study?
Keep in mind that obesity is still correlatd with a lower survival than being normal, or a little chubby. That said, definitly do not stress about not being thin enough as long as you’re not vastly overweight.