WHY DOES MFP calculate what you will be in 5 weeks ?

It's just an estimate based on the math.

I've been losing more than they estimate. That's what it is an estimate it's just a guide to give you some encouragement to wait you may lose.

I've not come close to the estimate myself, but have lost weight.

I guess the real reason for showing that is so you can focus on the big picture. Eating healthy for a day might give you 0.1 lbs off. Wow. Not! But by see at the end of the day that all those little bits per day add up over 5 weeks time, well, that's motivation to keep going.

It's generally right for me - I've been recording it for months now and cross checking.
All depends on how I ate on the day - if I had a day where I go over then it gives a wrong (weight too high) 5 week result. On days where I'm on track it is giving me a reasonable 5 week loss value.

yes but has anyone come close too loosing what it tells you for example I weigh 81 kilos it tells me if i continue to eat as i am it will be 76 kilos estimated

Because if you exercised that way and ate exactly that every day for 5 weeks then you probably will weigh that much. But keep in mind it doesn't take into account the way -your- body works, so really the number is useless and is only there for encouragement purposes.

It's just an estimate, as everything is an estimate. The only way you learn about yourself is through observation of the effect of your eating and exercise habits.

I don't usually get the message because I don't close out my day. But when I do and it predicts a weight gain, I use it to goad myself.

Meh and I thought this would be about why it's 5 weeks instead of say 4.

Because it is?

I doubt there's a really well thought out reason for it rather than the person thinking up this feature figuring that 5 weeks was a good time span.

There could be few reasons why you are not getting the exact result as the predicted: you may not be eating the exact calories as that day every of the other days of the five weeks, or you could be overestimating calories burned from exercise or underestimating the ones from food.

The way it works is (I presume! that's the way I'd do it if I was doing the app) it checks what is your calorie deficit for the day, multiplies that by 35 (five weeks), and then converts the total calorie shortage into predicted pounds lost.
For example, if I need 2000 to maintain but I log 1500 one day I'm 500 in deficit for the day. I'm 3500 in predicted deficit over the week, which will mean I'd lose a pound, so for 5 weeks it will predict 5 pounds loss. If I have my weight as 180lb it will tell me that based on that day I'd be 175 in five weeks :-)
If the next day I eat only 1000 calories it will tell me that I'll be 170 in five weeks.

If your calories vary every day it won't be very accurate prediction as there will be big fluctuations from day to day. I also have no clue how metabolism is taken into account (do you always loose a pound of weight if you are 3500cal short? how much fat, how much muscle?)

I use it as a fun estimation to keep me going. I'd sometimes log that cake before I eat it and hit the button, often I don't want to eat it afterwards :-)

Not sure if this is any clearer

But why does it continue to say 5 weeks??? I have lost and keep losing but it has been telling me I will be at my goal in 5 weeks for about 3 weeks now and never lowers the number of weeks!

I actually wish it wasn't set at 5 weeks. How about next week instead? xD