I live in a coastal area with a lot of lightning. When a bolt strikes the water, does it kill the fish? —Jennifer Pace, Sarasota, Fla. Lightning is far more dangerous to human swimmers than to fish. Why? Because much of the current stays on the surface of the water. Fish and other marine animals are usually found deeper. If a person diets and loses a large amount of weight—say, 100 pounds—how long does it take for his or her skin to shrink to the body’s new, smaller size? —S. Bullard, Hillsborough, N.J. It doesn’t ever happen. Obese people who lose this much weight will need surgery to remove the excess skin.