You’re not imagining it: There really are differences between the way men and women diet, lose weight and respond to exercise.

Some of the differences stem from biology; other differences are behavioral. But though many of these seem to give men a head start, they shouldn’t be taken to imply that guys have it easy. No matter who you are or where you’re starting, the road to your ideal weight is difficult at best, and confusing for most.

But the information that researchers are unearthing about the differences in the way that men and women lose weight inspires hope that the next generation of weight-loss advice will be more tailored and effective than the generic tips that have gotten Americans no closer to sliding into their dream jeans. (More than a quarter of Americans are obese, according to a May Gallup poll, a number that has been ticking upward for years). Although experts have long insisted that losing weight is simply a matter of burning more calories than you consume, they now say that it’s more complicated.

First, there is the matter of muscles and metabolism. Men tend to have more muscle than women, and because muscle burns more calories than fat, men tend to have a faster metabolism, too – anywhere between 3 and 10 percent higher than women, studies have shown.

And at the gym, that difference just gets exacerbated. Women, worried about bulking up, tend to lift lighter weights and focus more on cardiovascular fitness, while men tend to gravitate toward the kind of heavy lifting that boosts muscle composition and metabolic rate, said Jim White, a Virginia Beach-based ncertified personal trainer.

When it comes to food, there is evidence that men and women’s brains are wired differently. In a study published in the January 2009 issue of the Proceedings of the National Academy of Sciences, even though women said they weren’t hungry when asked to smell, taste and observe treats such as pizza, cinnamon buns and chocolate cake, brain scans showed activity in the regions that control the drive to eat (not the case for men).

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.

Researchers speculate that this is basically a Darwinian issue, in that it’s the female body’s natural way of fighting energy deficits in order to preserve fertility and perpetuate the species. When women aren’t getting enough calories, ovulation and hormones that make reproduction possible get suppressed.

But there’s more than just biology at work here. A motley complex of emotional and behavioral issues have a powerful impact on the way men and women approach weight loss.

Cynthia Sass, co-author of “The Flat Belly Diet!,” says she has seen many women gain weight as soon as they get into a relationship with men because they start eating as much and as often as their male partners. “That turns out to be too much,” she said.