Diligence

Most people have noticed that it’s hard to lose weight, but easy to gain it. This is a relic of harder times, when food was not as abundant as it is today. Our genetic taste buds made energy-dense food desirable because it was necessary to pack away calories so we could make it through the thin times. We feasted when we could, in preparation for the famine.
But now that we live in a time of abundance, that system predisposes many of us for weight gain and retention. And for obese dieters, this system is even harder to overcome; after weight loss, they become better at using fuel and storing fat, making it harder to keep weight off. However, this isn’t to say that many haven’t lost weight and kept it off successfully.
It just means you have to be diligent.