Then, there’s biochemistry. In women, ghrelin — the “I’m hungry” hormone — spikes after a workout, while leptin — which tells the brain ‘I’m full!’ — plummets, according to a 2009 study in the American Journal of Physiology — Regulatory, Integral and Comparable Physiology. Not so in men. So post-workout, women tend to eat more, which puts them at risk to gain weight. Men don’t experience this same hormonal fluctuation.
Sure, you can lose weight quickly. There are plenty of fad diets that work to shed pounds rapidly -- while leaving you feeling hungry and deprived. But what good is losing weight only to regain it? To keep pounds off permanently, it's best to lose weight slowly. And many experts say you can do that without going on a "diet." Instead, the key is making simple tweaks to your lifestyle.