Explain about the Weight cycling - energy balance?

There are a number of obese people who keep losing and gaining weight a number of times in their lives. This is called the Yo-yo effect. Every time they regain lost weight, it takes longer to lose the same amount of weight and also less time to regain it. This frequent losing and gaining of weight is associated with health risks related to normal functioning of the heart. Psychologically also repeated weight gain is quite demoralizing for the obese individual. Withstanding, any amount of intentional weight loss results in significant reduction in all cause, cardiovascular and cancer mortality.