exercise

This week, Mark Sisson — former professional athlete, founder of Mark's Daily Apple, and developer of the Primal Blueprint health & fitness lifestyle — returns to discuss nutrition. In his opinion, it's the single most important factor for a healthy life.

While other key components like physical exertion, good sleep, de-stressing and sun exposure contribute to overall health and well-being, too (see our 2013 interview with Mark for a full background on his recommended regime), the food we eat can literally determine which of the genes in our genetic code get activated and expressed. So, in a very real way, we indeed are what we eat.