This is a big question - one that I can't answer thoroughly in one post, and one that actually doesn't have a right answer because everyone is so unique. However, I want to share some thoughts on this topic because I think that not eating enough can undermine people's ability to resist binge urges. This post will give you some basic, broad guidelines to work with, and is meant especially for those who feel unable to fully rely on their hunger signals / intuitive eating.
(Since I'm talking about nutrition, I will again remind you that I'm not a nutritionist or medical doctor, and to please to seek the guidance of health professionals if you feel you need it.)
Many recovering binge eaters already have a feel for what constitutes a satisfactory quantity of food per day, but some don't. Some people think that a banana for breakfast, a couple hard boiled eggs and an apple for lunch, and a grilled chicken salad for dinner should be plenty. In reality, that amount of food wouldn't even be enough if you were lying in bed all day. Many women I’ve spoken to believe they only need about 1300-1800 calories each day...or at least that's what they think they "should" be eating in order to lose weight. Even though that's not extreme starvation, an energy intake that low is going to keep the body in “survival" mode - keeping you focused on food, plagued with cravings, and making binge urges much harder to resist.
Your resting metabolic rate - what your body needs just to support it’s basic functions at rest - is approximately ten times your body weight. So, if you weigh 150 lbs, you need about 1500 calories a day if you lie in bed all day and do nothing...not walk, not talk, not brush your teeth, not chew food, not go to work, not exercise...etc. Is it any surprise that a 150 pound woman might not be able to stick to a 1400-calorie-per day weight-loss diet? That’s not even enough food to support her basic life-sustaining functions!
I personally believe that anything less than 2000 per day isn't usually enough for people, especially people with a history of calorie deprivation and binge eating. A range from about 2000-3000 usually works best for people, depending on their level of activity and metabolism. I realize that's a wide range, but everyone is truly different in their needs. I don’t believe in getting overly mathematical with eating, or counting calories for any reason except to make sure you are getting a normal, nourishing amount of food. Don't feel like you need to monitor your calorie intake closely, and don't get obsessive about making sure you are getting the "right" amount; but it can help to loosely monitor your intake for a short time to get a feel for what is normal.
The culture of weight loss is thankfully beginning to shift away from calorie deficits, but it's been that way for so long that it can be hard for someone to believe that eating 2000 or more calories per day isn't excessive at all. If you truly think that 1500 calories is enough for you, I would recommend buying a simple electronic monitor to estimate how many calories you are actually burning. If you have hard proof of how many calories you are using, it can help you realize that upping your intake isn't being excessive - it's actually cultivating a healthy metabolism. I think the reason that over 2000 calories can seem like too much for some people is leftover from the unhealthy low-fat craze that's also (thankfully) ending. Yes, 2000 calories of plain rice and salads with non-fat / low-cal dressing sure seems like a high volume of food; but if you instead focus on adding some nourishing, calorie-dense foods like proteins and healthy fats, you will be eating normal-sized portions that are also satisfying.
As I've said before, my book is not a method to become a better dieter. Please do not use ideas from my book or workbook to resist all urges to eat more than your calorie-restrictive diet allows, or to ignore real hunger signals. Trying to resist urges to eat over, let’s say, 1600 calories per day is the opposite of the intent of Brain over Binge. Limiting food intake while trying to resist urges to binge would be extremely difficult, and is simply not compatible because of survival instincts.
Something to note is that increasing calories can sometimes blur the line between normalcy and binge eating for those whose binges were small. If you were eating 1200 calories per day on your "diet" (and binge eating on top of that); and now suddenly you are nourishing your body with 2200 calories per day, you may feel like you are giving in to your lower brain. This is not the case at all. You are giving your body what it needs. For example, let’s say you are doing a very challenging exercise regimen and your body is needing around 3000 calories per day to support your routine, but you are subjectively considering anything over 2000 a binge; then you can see how that will be problematic. Eating the extra 1000 calories per day might feel like you are indulging, but you aren’t. The goal is not to banish your appetite or desire for food completely, but to restore your lower brain to its normal function in your life.
One last argument against calorie restriction is that dieting weakens the prefrontal cortex...
Remember the part of your brain that allows you to resist the binge urges - the prefrontal cortex? The rational prefrontal cortex gives us self-control - a function that happens to be unnecessary for your immediate survival during a food shortage. When you are starving, what do you think is going to be the first part of the brain to be shut down? Definitely not your primitive brain that is in charge of keeping you alive! This is another reason why dieting leads to binge eating. When you are starving, your prefrontal cortex is in an energy-depleted state; so you'll feel more out of control and less capable of resisting binge urges.
Eating a satisfactory quantity of food ensures that you have a proper functioning prefrontal cortex that is able to resist binge urges. If you are tempted to keep starving yourself, know that it will only hinder your progress. If you’ve gained some weight from binge eating, and you are impatient about losing it, know that another diet will just ensure a slower metabolism, more binge urges, and likely more weight gain in the future.