For weight loss, somebody that trains 3-5 times a week would need 15x their body weight (in lbs), a fighter will probably need 18x or up to 20x in order to maintain their bodyweight. minus 5 from this to lose weight, so a fighter would want to eat 15xbodyweight to lose weight. For good weight loss, you want to cut out anywhere from 500 calories to 1000 calories a day for a while. Give yourself one cheat day too, and REALLY cheat. We're talking cheesecake here. that way you wont' crave it the next week.

Cutting more than 1000 calories a day tends to put you in famine mode that somebody else mentioned, which is where i've been for the last 2 years :( Before I was 6-7% body fat at 175 and I probably ate around 3,000 calories a day. Because I've been so busy since then I'm lucky to get 2,000 calories a day. The result? I'm now 185 at 11%. Makes no sense but that's how the human body has adapted.

For all of you curious about the atkins diet, there is a much better ketogenic diet option called the cyclical ketogenic diet. There is a book by Lyle McDonald on it that is a much better resource than the Atkins book for those of us who know something about nutrition and exercise. (Atkins wrote for the Oprah crowd) The book may be out of print but here's a good article by him:

http://www.thinkmuscle.com/articles/mcdonald/training-on-ketogenic-diet.htm

Basically, the Atkins diet works great but few people can stay on it fora long time because it basically feeds off of your low self esteem and will power :) The cyclical diet gives you 1-2 cheat days where you can eat all of your junk, which also gives you better performance while losing weight. I personally don't believe any low carb diet, meaning one where you take in less than 30 grams of carbs/day, should be used long term or for life. Just if you want to lose weight, be it 300 lbs. or 12 lbs. I personally always had better results on the zone diet. If you use the zone, be sure to use your body's caloric needs rather than the author's recommendations because they are too low for athletes.

The zone diet uses blocks to get the right amount of calories/nutrients in your diet. ignore how he recommends finding how many blocks you need. Here's my example:

I'm 185, but I want to be 175. (let's also assume I'm training a lot here and say that I'd need 20x175 to mainain my bodyweight) I'd use 175x15 as the amount of calories to figure my blocks with because I wont' be depriving my body of more than 1,000 calories. (if I was,I would have to work towards less weight loss first) I would have to get to a lower weight, say175 x 15 = 2,625 calories a day

So...The zone diet recommends a 40/30/30 ratio of carbs, protein, and fats. Break this down, and it translates to one carb block being 9 grams (example: a banana would be about 3 blocks), protein block equalling 7 grams (so a normal sized chicken breast is about 4-5 blocks), and a fat block is 3 grams. (a little bit of butter or olive oil) So for every block of one you eat, you have to eat one of the others too. this gets a little tricky at first but as you get better at reading nutrition labels, it becomes instinct.

If I need 2,625 calories a day to get to 175, first I need to figure how many grams of protein I need a day. So 30% has to be protein: .3x2,625 = 787.5 calories from protein. 787.5/4 (there are 4 calories in a gram of protein) = 196.875 grams of protein a day. So, a protein block is 7 grams? Figure that's 197/7 = 28 protein blocks. So then I need 28 carb blocks and 28 fat blocks to go with it. Get the complete book of Food counts by Corrine Netzer to figure how many calories/protein/fat/carbs your favorite fast food or restaraunt food has, figure how many blocks your regular favorite foods have by reading the labels, and go from there. It takes at least a few weeks to get into a good set program that you feel comfortable with, but you will definitely notice a difference in how you feel.