According to Traci Mann, PhD, professor of Psychology @ Univ. of Minnesota, most people do not succeed in keeping that weight off.  The majority of people gain the majority of the weight  back in 2 -5 years.

In 2016 researchers published a study on former”The Biggest Loser” contestants in the journal “Obesity”.  The results found that those dramatic transformations don’t last.  Not only because once they leave the show they’re not doing extreme, hours-long workouts.  On average, the contestants regained 70% of the weight they lost, in part because of metabolic adaption.  Because we have evolved to survive during periods of food scarcity, our metabolism becomes more efficient when we lose weight.  Your metabolism becomes more efficient, you burn fewer calories, leading to regain.

Studies have found that after losing weight, levels of leptin, which decreases appetite, decrease, while levels of ghrelin, which increases appetite.  You are more likely to be hungry and less likely to feel full on foods that used to make you feel full. Oregon research Institute  looked at the brains of college students who had not eaten for 4-6 hours.  They found that those students paid more attention to photos of palatable food and food cues.

Food gives you a bigger high when you do eat.  Your brain releases dopamine, the neurotransmitter that is produced when your brain expects a reward.  The brain releases more dopamine if you are calorie- deprived 

Maintaining a balanced diet including fruits/vegetables.avoiding sugars  works the best when weight loss is involved.

Do things that will make you healthier, which may also help to lose weight.