I need someone to explain how MFP's net calorie system works

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rrjs
rrjs Posts: 46
in Health and Weight Loss
First off, to help you get some perspective on my calorie needs, I'm 19, 5' 1'', and 127.5 lbs. I don't know how I would 'label' my normal activity level - during the typical day I probably walk maybe 50 minutes total to and from classes. And I usually go to the gym 4 times a week and burn anywhere from 200-350 calories.

I'm trying to get back down to 120, which was my pre-college weight and where I feel most happy and comfortable. MFP has been pretty helpful but I'm still confused over how to approach net calories. MFP has calculated my daily calorie needs to be 1200, and so far I've been EATING 1200 but my net calories are usually under 1200 at the end of the day.

I just don't understand the concept of eating back all of the calories I burnt at the gym! Isn't that the purpose of working out in the first place? I feel like I'm defeating the purpose by coming back from the gym and eating back everything I worked hard to burn off.

Can someone shed some light on how this works and help me understand, so I can go about reaching my goal in a healthy way?

Replies

  • EmilyAnn89
    EmilyAnn89 Posts: 564 Member
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    you are supposed to eat your exercise calories because when you enter your information the amount of calories they tell you to eat per day are already set at a deficit. so basically anything you work off is extra calories you are allowed to consume. some people on here eat their exercise calories and some don't. i do, (and my ticker says 8 lbs., but i used this site a year ago and lost 20) i always have eaten my exercise calories and have had no problem losing weight. hope this helps :)

    EDIT: also, 1200 calories is the LEAST amount you are supposed to consume in a day, or your body can go into starvation mode which will make it harder for you to lose weight . good luck!
  • ouryear002
    ouryear002 Posts: 325 Member
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    Don't count your exercise in your daily actvity. If you mostly sit in class and walk a bit, you are probably light active. As to your calories-Eat them. There is a "Newbies, Please read" post pinned at the top of this forum. In it you will find a link to a posting that explains the concept very well. If you have questions after you read it, come back!
  • colonelangus
    colonelangus Posts: 46
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    It's simply taking your given calories and adding in the exercise calories. If you don't want to eat them you don't have to.
  • chris808
    chris808 Posts: 28
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    Hi, this is a FAQ here, check this post for the definitive explanation of why you should eat them.

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

    Chris
  • Paige1108
    Paige1108 Posts: 432 Member
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    Sense you are so close to your ideal weight you may need to eat your exercise calories more than anyone else. When you are lean your body will burn, food, muscle and fat in that order, if your not eating enough. So you really neeeeeeeeed to eat your calories to help your body to know that it's okay to use the fat. There are two posts you must read if you are super close to your target weight.

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

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

    Okay three posts you must read
    http://www.myfitnesspal.com/topics/show/10589-for-those-confused-or-questioning-eating-your-exercise-calo

    And for me, whole point, of exercise is to build lean muscle, so I can look hot, and get my heart healthy.

    Good luck on your journey. I hope you find a system that works for you.
  • lmanzi219
    lmanzi219 Posts: 32 Member
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    MFP calculates you target calorie goal, in your case 1200, so you are at a 500 calorie deficit for the day, which puts you on track to lose one pound a week. Your body actually requires 1700 for normal daily activities. When you burn at the gym, that is added to the 500 calorie loss, so for example: You only ate your 1200 calories for the day, but you burned an extra 300 at the gym. Then you would be losing 800 calories worth of weight for the day, so your net would be 1700 - 500 = 1200 - 300 = 900 net calories. Your body should never go below 1000-1200 net for the day otherwise your metabolism can slow down and you could possibly go into starvation mode. Starvation mode is when your body isn't getting enough caloric energy so it conserves as much as it can to not lose weight which is the opposite of what you're trying to do. Working out allows you to eat more and since your body is processing more food, your metabolism will become faster and you will lose more weight. Good luck! I hope this helps a little.
  • Frozen4Time
    Frozen4Time Posts: 1 Member
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    The way it works is this...

    1) Everyone has a base metabolic rate (BMR). This is the number of calories that if you did nothing (i.e. laid in bed all day) your body would burn. There are ways to actually measure this but it can be estimated through your age, height and weight. If you laid in bed all day this is how many calories you would need to eat to maintain your weight. Lets say for me, this is

    BMR: 1800 calories

    2) Then you add in how active you are on a normal day (without exercise counted). So do you walk around a lot for your job, do heavy lifting, or just sit at a desk. You then add these calories to your base metabolic rate. This is now the number of calories per day on average you would need to eat to maintain your weight, assuming you aren't exercising above and beyond that.

    300 calories per day puttering around for me.. so

    1800 + 300 = 2100

    3) Now you tell MFP how fast you want to lose weight. A basic rule of thumb is that 1lb of fat equals about 3500 calories. To loose 1lb of fat you need to expend 3500 more calories over a given time period than you eat. So for example if you want to loose 1lb a week, then you need a weekly calorie deficit of 3500. There are 7 days in a week so you need a 500 calorie a day deficit to get a total weekly deficit of 3500 calories.

    500 per day deficit.

    4) Take #2 and subtract #3. This gives you the number of calories per day you need to eat to achieve the desired rate of weight loss. Again this assumes no exercise.

    2100 - 500 = 1600

    If I eat 1600 calories a day I will lose a pound a week. This is the initial per day calorie goal that MFP will show you.


    5) Now for the interesting part.

    If you exercise, you now have to eat those calories back to keep the rate constant. Finishing up my scenario. If I have a normal daily burn of 2100 and I am going for a 500 calorie deficit we have see that I need to eat 1600 calories. However, if I exercise and burn 400 calories, then in that day I have burned 2500 calories (2100 from my normal day, plus the 400 from exercise). If I still want to have only a 500 calorie deficit it now becomes:

    2500 - 500 = 2000

    So on the day that I burned 400 extra calories, I need to eat an extra 400 calories so that my deficit remains at 500 calories. MFP does this because you tell it you want to loose 1lb per week. So it keeps your daily deficit at 500 calories.

    The main reason it does this is because if I only ate 1600 calories in a day and then ran 10 miles, I would burn 1000 of those food calories off, only providing my body with 600 calories for the rest of the day. This would not be healthy. So MFP asks you how fast you want to loose weight, and then keeps your daily deficit at that.

    So you follow the formula

    BMR + (Average Calories Burned From Normal Activity) + (Calories Burned From Exercise) - (Daily Deficit) = # of calories you eat in a day.

    In this formula there are only two things you can control, 1) The number of calories burned in Exercise, 2) The target daily deficit you are aiming for. If you hold the daily deficit constant, then the more you exercise the more you eat. If you don't eat back the calories you burn off at the gym you will lose weight faster, but might be under eating.

    6)

    Just remember 3500 calories = 1lb of fat. Most people recommend loosing between 1 and 2 pounds a week. Anything more than two is not sustainable and healthy. So given that you are looking for between 3500 and 7000 calories per week. Which means between 500 and 1000 calories per day. You want to pick a target loss rate and then stick with it.

    A final way to look at it is, if you want to loose 1lb a week, you need a 500 calorie deficit a day. If you burend 500 calories at the gym each day, then you wouldn't have to eat any less (i.e. no diet based calorie deficit) since all your deficit would be from exercise.


    Hope this helps.

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