Eat More, Lose More. (Really?) By Justine Holberg

This is exactly where I am. MFP will not let me go lower than 1200. I'm 120 lbs and very petite frame and 5'4". No matter what I change in the goal section, or weight-loss goal section, how much I exercise or even when I enter no exercise - it NEVER goes below 1200 calories. I've tried changing it for maintenance, 1 lb weight loss and 2 lb weight loss and it still stays at 1200. Surely that can't be correct for both maintenance AND weight-loss. I personally - net about 800 or 900 calories a day with logging in 400 calories burned in exercise. I just try and eat when I'm hungry and stay active... but it is frustrating that it's not accurate for ALL people.

This is because at your height and weight, even if you are very petite, you still shouldn't be under 1200. I would suspect you had some info/settings wrong somewhere if it gave you that number at maintenance. At your height and weight, your BMR is about 1274 (maintenance would never be below this). With sedentary activity level, you add about 300 (maybe a little less, but shouldn't be a lot less), so your maintenance cals would be about 1575. With already being quite lean, your loss goal should NOT be higher than 1/2 lb per week - higher than that will not only not be healthy, it's also HIGHLY unlikely you'd succeed at that, so you're just setting yourself up for failure. So, at 1/2 lb loss goal, subtract 250 from 1574 and you get 1324 daily cal goal, before exercise.

When you eat too little, especially when you have very little body fat to start with, your metabolism will slow and your body will break down muscle, rather than fat. I'd recommend reading these threads that help explain metabolism and why it's important to fuel the body. Good luck to you!

http://www.myfitnesspal.com/topics/show/61706-guide-to-calorie-deficits

http://www.myfitnesspal.com/topics/show/3047-700-calories-a-day-and-not-losing

http://www.myfitnesspal.com/topics/show/10589-for-those-confused-or-questioning-eating-your-exercise-calo

http://www.myfitnesspal.com/topics/show/153704-myth-or-fact-simple-math-3500-calories-one-pound-eat

@lodro - I am so please you posted those links. I just started intermittent fasting (leangains) and I must say it's like being set free from the cycle of constant eating (every 3 hrs). The body needs a break from food and you are right the whole not skipping breakfast thing was created by cereal companies to encourage people to buy their breakfast cereals!

Whilst the information from the original poster may be true for many it's time that everyone looked at both perspectives and stopped worrying about 'starvation mode' which is so unlikely in 99% of people.

They should determine their caloric intake according to a changed, and lower, metabolic rate. This is not caused by "starvation mode", but by the fact that now your body really does need fewer calories to function. The lighter you become, the smaller the margins will be.

This is true, but if you (as in everyone) update settings in MFP frequently, MFP decreases cal goals and exercise burns automatically, according to weight loss.

You have to not only "check in" for your weigh in, but also then go to Goals, Change goals, Guided (if you are using MFP's calculations) and just hit enter. It then recalculates your daily cal goals and exercise burns based on your lower weight.

I actually encountered this today and the system automatically told me "hey you've lost some weight (I hit my 11th pound) - you need to change your goals" and took me right to the guided or custom settings update you referenced. It was nice to know that the system isn't just recording my information but using it proactively to help me stay on the right path. My only gripe was that it actually raised my calories so I went back and did the custom and updated it to what is was so that I still maintain my 1lb or so a week loss until I either start exercising or get closer to my goal and start to transition to management.