Why do people say losing weight is mainly about diet

I think MFP calculates the calorie reduction of 500 calories per day for that 1 lb/week . So say you need 2000 calories to maintain and it lets you eat 1500 calories...you are supposed to lose a pound/week.

If you burn 250 calories with exercise...you can eat 1750 and still have your 500 calorie reduction...see?

or you could go easy on yourself and say...reduce your food intake by 250 and exercise for 250 and just not eat what you exercised off. That way you don't have to eat 500 calories less.

It only gets harder when we try to pressure ourselves and say...Oh I will eat 500 calories less ( 1500 intake ) and exercise for 1 hour ( 500 calories ) and I will lose faster because your net is now 1500 - 500 = 1000 calories/day.

That being said, that 3500 calories = 1 lb doesn't always hold true. When I did WW I went from 160 t0 148 quickly without exercise. But when I switched to exercise and a low carb diet the weight I lost was probably 3 lbs but the inches and body fat reduction was pretty significant.

its exactly what they say...two women can be 130 lbs and yet look very different from each other depending on how they got to 130 lbs.

MFP gives me 1200 cals. If i set activity level to sedentary. I'm 5ft 7, 151 pounds and female and am happy to lose a pound a week.

I've just got a fitbit. Yesterday I did two dog walks, went to the shops and did JM body revolution. This gave me an extra 1000 calories which is HUGE. I ate about half which then put me at a much mire manageable 1700 calories to eat, but still this 500 calories deficit would allow me to in theory lose an extra pound a week.

Am I confused somewhere?

The key words here are "in theory".

The body isn't a simple calorie/fat cash machine.

A calorie deficit does not necessarily mean that your body has to give up fat.

It can slow down metabolism, not do maintenance, lose muscle or do any number of things that is not liberating fat.

Even in the face of exercise the body does not have to give up fat at anywhere near 3500cals=1lb fat (which is grossly inaccurate anyway). The body has less nutrients AND it is being worked harder ... Hmmm, likely to want to hang onto some fat maybe?

Likewise, a calorie surplus does not necessarily mean that your body has to put fat on.

It can speed up metabolism, increase temperature, increase involuntary movement, gain muscle, etc.

And, here is the key thing about why diet is important ... what those calories consist of have a HUGE bearing on what the body is likely to do with them.

Yes, calories count at some point but I think we give the body too little credit for being able to remain healthy and lean in the face of a reasonably varied caloric intake.

I eat what I see as filling, nutrient dense, long-term health-promoting diet and looking good naked comes as a nice by-product.

And I don't do much exercise ... a bit of walking, some push ups ... eat right and you don't have to ...

I'll say again:
1) You don't HAVE to gain fat in a caloric surplus
2) You don't HAVE to lose fat in a caloric deficit (and never mind the 3500cals=1lb fat lost nonsense)

You lose weight in the kitchen, not in the gym.

exercise makes a big difference, but i suppose if you have a horrible diet to begin with then just changing that would make a big difference as well

What I'm trying to say is that doing not a ridiculous amount of exercise means I can now eat. More sustainable amount, plus lose double the amount so exercise for me makes a HUGE difference.

Or you could realize that you really aren't sedentary, eat a reasonable amount, plus your exercise calories back.

I'm only 2 inches taller then you and when I was losing, I was eating between 1500-1800 calories a day... before exercise calories.

Now that I'm set to TDEE, I can eat up to 2100 a day and lose.

What works for me is I eat my BMR only. 2100 cals. If I am running pure low carb I can add 500 calories and still easily lose. I have been slacking this last few weeks but still managed to lose 5 lb by just sticking to my calorie limits even with only hitting the gym twice last week.

Reducing calories by 15-20% below TDEE is a good place to start. A larger deficit may be necessary in some cases, but the best approach would be to keep the calorie deficit through diet small while increasing activity level.

Example 1:
Your weight is 120 lbs.
Your TDEE is 2033 calories
Your calorie deficit to lose weight is 500 calories
Your optimal caloric intake for weight loss is 2033 - 500 = 1533 calories

Example 2:
Your calorie deficit to lose weight is 20% of TDEE (.20% X 2033 = 406 calories)
Your optimal caloric intake for weight loss = 1627 calories

We’ve been trying to figure out an exact NUMBER of calories that everyone should be eating, without recognizing that everyone is slightly different. In truth, the calories aren’t the end game. Your body is. So the EXACT amount of Calories that are right for you is the EXACT amount that will allow you to maintain your ideal bodyweight no matter what some calculator or chart says.

In other words, an online calculator might tell you that you need to eat 2,500 calories
per day to maintain your ideal bodyweight. But the only way to know for sure if this is
the right amount for you is to test it out. If you gain weight or can’t lose weight eating
that much, then you know you need to eat less to lose weight no matter how many
calculators and text books say otherwise.

This doesn’t mean your metabolism is broken, it just means the estimate of your needs
was just a bit off.

-John Barban

It is silly to get hung up on a calorie number like 1200 calories. This number is relative to your BMR. If you are a bigger person this is a low number, if you are small like me this is a large number, barely below my RMR.

If you have a lot of body fat reserves you would be surprised at how little you can eat (unless you have emotional eating issues or disorders). The leaner you get the less your body has to draw from and then you have to taper up your calories. There is no such thing as starvation mode for woman over 12% body fat or men over 6% body fat. I pretty much proved that for myself by staying strong and building muscle and doing what I did. I'm the leanest, most muscular, and most fit that I have ever been in my life at almost 52 years old.

Separating out the the two things worked for me:

1) Eat less to lose fat.

2) Exercise to gain or maintain lean body mass.

Ignore exercise calories because it's insignificant when you don't have to worry about starvation mode anymore and it's highly over rated. Of course you burn energy, but not nearly what any of the devices say you do.

If you are not doing a weight training routine you need to start one and do it the rest of your life to ward off osteoporosis.

The full story of my struggle with this here and why I know this is true --> http://www.myfitnesspal.com/topics/show/740340-i-lost-60-lbs-at-age-51-anyone-can-any-workout