For today’s edition of Dear Mark, I’m answering three questions. First up comes from Carlos, who is worried about the effect of sun exposure on skin aging. Is the type of sun exposure I recommend good for vitamin D levels but bad for the health and appearance of skin? Second, how can someone eat all the vegetables I recommend while keeping their carb intake below acceptable levels? Aren’t veggies really high in carbohydrates? And finally, what “breaks” a fast? How much protein, fat, carbs, and overall calories can a person get away with without shifting completely out of the fasting state?