can i have macroni ? during diet ?

1. don't trust the initial setup that MFP provides. If you put in the wrong/inaccurate information, it'll tell you to eat an amount that may not be applicable.
2. Make sure you eat enough.
3. Figure out what works for you and is sustainable/healthy/long term.
4. avoid fads. don't buy in to any "Hey, try the twinkie and vodka diet"
5. Don't cut out anything now that you don't plan on literally giving up forever.
6. GET A FOOD SCALE. Weigh everything. No, seriously.
7. Get an HRM with a chest strap. You'll at least have a better idea of what you're burning. It'll be more accurate than the generic info in the exercise database.. and even more than the cardio machines. This is great for steady state cardio (run/walk/etc)
8. Don't go balls out. You'll burn out. I see 300 lb people show up here, instantly start working out and cutting their intake SEVERELY... trying to cut out all of their carbs at once.. whatever. Take it slow. Figure out how much you need to eat FIRST in order to lose.. then incorporate exercise.
9. Don't cardio yourself to death.
10. Take the information on the forums with a grain of salt. A lot of people that have been here for a while.. and have been successful, may seem jaded. They give out GREAT advice day after day, only to be met with people that refuse to listen.
11. Eat real food. Not diet food. Not "low fat, sugar free, now without X." It's easier to get/find/count.
12. don't set time restrictions.
13. measure yourself weekly. Don't just weigh. Measure and take pictures.
14 BE PATIENT.
15. Avoid forum topics that have "1200" in the title. It's just full of butthurt. Lots of it.
16. If you ask a question on the forum, give as much information as you can ("yes, I have a food scale and weigh my food" is worlds better than "I eat a palm full of miscellaneous boiled chicken parts..sometimes.")
17. Be honest with yourself and honest with us.
18. This isn't a game, it's about changing your lifestyle. Do that.

pretty much that.

...and don't fall into the "1200 calorie" vertigo of suck because of:

the typical MFP users does this:
1. I wanna lose weight, let's try MFP.
2. OH! Wow, it tells me I can lose 2 lbs a WEEK? AWESOME!
3. I just sit at a desk when I'm not working out, I guess I'm sedentary.
4. MFP tells them 1200 calories, and they don't even eat that.. then they work out on top of it.. creating an even bigger deficit.
5. Lose a lot, fast, brag about 1200 calorie success.
6. Come back in a few months trying to figure out why they're dizzy, tired, not losing weight.
7. Get on the forums, ask why they aren't losing.
8. Get two responses (I eat 1200 and lose) (I eat 2200 and lose)
9. Argument ensues about who is right.

Now. That being said. These threads happen hundreds of times per day. Most times, and I mean really.. seriously.. 95% of the time.. people get the 1200 number because they don't put the right information in when they set up the account. There are a great number of people that are trying to help. I'm one of 'em.

I'm a hardcore advocate of actually finding out what works for the individual.. by means of other calculators, averages, time, practice, and patience.

Blanket prescriptions of 1200 calories "because it worked for me" is more harmful to the generic new user than the "figure out what you need to eat." Unfortunately, one is a LOT easier to type.

Find out what you need: http://scoobysworkshop.com/accurate-calorie-calculator/

and make sure to read: http://www.myfitnesspal.com/topics/show/1080242-a-guide-to-get-you-started-on-your-path-to-sexypants