The AHA says that the best way to maintain a healthy weight and to decrease the risk of heart disease is to eat a healthy diet and to limit added sugar to no more than 100 calories a day for women and 150 for men.

CNN: Sugary drinks linked to 180,000 deaths worldwide

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

ECONOMIST: The ageing brain

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?

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