A negative correlation was found between weight and distance walked. Would you conclude that walking causes lower weight and can you think of an alternate explanation for the findings?

Negative correlation implies an inverse relationship between a person's weight and the amount of distance that they walk (say on an average day). So you can conclude that heavier people are more likely to walk less. Lighter people are more likely to walk more.

Remember though that correlation does not always equate to causation. What this means in practical terms is that walking more does not necessarily mean you'll lose weight. Conversely, walking less does not necessarily mean that you'll gain weight. Or thinking of it another way, losing weight will not necessarily cause you to walk more and gaining weight will not necessarily cause you to walk less.