The brains of those aged 40 and older decrease in volume and weight by 5% every ten years.

ECONOMIST: The ageing brain

Every 10% reduction in car weight results in a 6% to 8% decrease in gasoline consumption.

FORBES: Magazine Article

Weight gain is driven by two trends: increases in calories consumed and decrease in calories expended.

CNN: Why we're getting fatter -- and what to do about it

Secondly, losing weight too quickly when you don't have a significant amount of weight to lose can result in muscle loss as well as fat loss, which can decrease your metabolism and make it more difficult to maintain your weight loss.

CNN: Is it possible to lose 15 pounds in one month?