Why is it generally harder for women than men to lose weight?

I don't actually think that's true, to be honest.

Men tend to have higher overall mass and higher muscle mass than women. So, pound for pound of total body weight, they have higher BMRs and burn more calories through exercise. Also, most restaurant portions are better suited to them than they are to us, especially to those of us women who are on the smaller side. So it may seem easier for men to lose weight.

On the other hand, we women have some advantages, too. For one thing, it's more societally acceptable for us to be watching our weight, "dieting" (I hate that term but you know what I mean), or counting calories. A lot of men doing those things try to hide the fact that they're doing them for fear of judgment. Also, on average, men tend to eat higher-sodium, higher-fat diets with fewer vegetables. While there are no 'good foods' or 'bad foods' when it comes to losing weight, it is a statistical fact that women live longer, and our relatively heart-healthier food habits are probably a contributing factor.

Finally, while men might lose quicker in absolute terms, often women are losing just as quickly or quicker in relative terms (as percentage of body weight lost per week as opposed to pounds lost per week).

IMHO: Don't compare. Do what works for you and the rest will follow.

I think it's because men have more muscle and also perhaps hormonal issues.

And men complain about it less?

I am not sure but I can defiantly see it between me and my boyfriend. We are losing weight together and I know for a fact I am more physically active than he is, and make better food choices. Though he consistently loses faster than I do. Also last week he completely went overboard and back to his old eating habits and gained around 4 lbs. yesterday he weighed himself and was down 5 lbs, after a couple days of eating at his deficient...

Yeah. Pretty much all of the above.

Being a large man (over 6' tall), I can easily create a huge calorie deficit with out dropping my calories very low. I eat 2100 calories a day (gross), and still maintain a 1000 calorie deficit. I also don't have to deal with so many hormonal fluctuations causing water weight.

Obviously, that will change as I get closer to goal, but it will still be easier for me to maintain a larger deficit than most women.

I have two good male friends, technically one is a relative, that started MFP about the same time I did. They can eat way more than I do and lose weight because of greater body mass. My male relative is 10 inches taller than I am. He can walk a mile in fewer steps than I can, too. But when it comes to weight loss, they have to create the same deficit to lose the same pounds as I do. My male friend was losing at about the same percentage of body weight that I am, about 1% per week. My male relative is less comfortable with that rate of loss. If you look strictly at total pounds lost, my male friend has lost the most, I am in the middle, and my male relative has lost the least. Why is the tallest male losing the slowest? Because he has a lower deficit then we do. If you ask him, he will say it is more difficult for him than me.

There are a couple of reasons why woman dont lose less but in a different way ( more fluctuations) than men. So not even less weight but they lose weight different.

1. Hormones
2. Muscle mass

for example

Most men have more muscle so they burn more. ( a lot of men but not all!)
Woman have their hormones which can cause ( i say can because not all women have this) fluctuate more around TOM days ovulation etc.

still all with all it is a matter of how big your deficit is. And every person is different. There are many factors that determent how you lose weight.
As long as you create a deficit so eat less calories than you burn, you will lose weight.

Those pesky hormones.

Has there been any large studies into this? Seems it's all from personal experience etc

I would suspect it comes from the fluctuations women have.

Like a guy loses consistently each week for months while the women gains, loses, maintains etc because of water weight. Tom etc

And since people seem to only remember bad times, they remember every week where the guy lost more but forget about the weeks where they lost as much or more than the guy.

Does that make sense.

Most likely it is due to a government conspiracy.