Large Calorie Deficit w/ Exercise

jtintx
jtintx Posts: 445 Member
in Health and Weight Loss
This doesn't really fit neatly into a category but here goes. Let's say you eat 1500 calories a day. Normally that's enough to not put your body into "starvation mode." But let's say you also exercise a lot that evening and burn 1500 calories. And say you do that 3 times a week. I don't want to eat back those calories...for one thing I'm not hungry. But what will be the body's response to such a large caloric deficit even though you're eating a substantial amount of food? Glycogen stores will not be replaced with food that evening so what does the body do? Burn fat? Burn muscle? Can the body replace glycogen by burning excess body fat? I'm not sure if I'm hindering my weight loss (fat loss) by having days with very large calorie deficits. ???
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Replies

  • janejellyroll
    janejellyroll Posts: 25,763 Member
    There is a limit to how much fat your body can utilize for energy per day, so if you're regularly exceeding that with very large deficits, you'll be targeting your muscle for loss. If you're burning 4,500 calories a week through exercise and you aren't hungry, your hunger cues may not be a reliable guide to ensure you're eating enough. If you aren't hungry that night, how about eating some of them the next day?
  • jtintx
    jtintx Posts: 445 Member
    VintageFeline wrote: »
    First off, starvation mode as used here is not a thing.

    Having too large a deficit consistently (this is the key here. you need to look at weekly averages) will cause your body to turn to muscle for fuel. Obly so much stored fat can be metabolised in a day, after that the body looks elsewhere.

    I'd also be curious to know what you're doing to burn 1500 calories. It would take me more than 3 hours of strenuous cardio as a 165lb woman to burn even close to that much.

    This was only an example but typically to burn that many calories I play 3 hours of competitive racquetball or go for bicycle rides over 50 miles.

    How much stored fat can be metabolized in a day?
  • jtintx
    jtintx Posts: 445 Member
    janejellyroll wrote: »
    There is a limit to how much fat your body can utilize for energy per day, so if you're regularly exceeding that with very large deficits, you'll be targeting your muscle for loss. If you're burning 4,500 calories a week through exercise and you aren't hungry, your hunger cues may not be a reliable guide to ensure you're eating enough. If you aren't hungry that night, how about eating some of them the next day?

    I do eat the next day but breakfast and lunch only amount to about 800-1000 calories before my next workout.

    Muscle loss is my concern. It seems that every time I gain and then have to lose weight I end up losing more and more muscle. I don't want to end up being "skinny-fat."
  • kimny72
    kimny72 Posts: 16,013 Member
    edited January 2017
    The real tell will be how much weight you are losing per week. Starvation mode is not a thing in the short term - you would need to have a large deficit consistently over a long period of time, and all that would do is slow your metabolism, not stop you from losing weight.

    If the info in your profile is correct, you have 35 lbs to go? You should be shooting for 1 lb per week. If you are consistently losing faster, you need to eat more. I think the healthy limit that is always mentioned is 1% of your body weight per week, but that would be the upper limit, fastest you should go. If you are prioritizing muscle-sparing, I think 1 lb would be the general advice.

    Depending on how accurate your logging is, and how inflated your calorie burns are (both of which are likely, it happens all the time!), your deficit might not be as big as it seems.
  • jtintx
    jtintx Posts: 445 Member
    edited January 2017
    jemhh wrote: »
    It's a bad idea. I feel like I am posting this constantly but I will do it again.

    Studies are showing that when energy availability decrease to a level below 20-30 calories per kg of lean mass (9.6-13.6 calories per lb), your system starts to adapt. Note that these adaptations begin within days of eating like this. It doesn't take weeks or months. One of the big adaptations is that your reproductive system senses that now is not a good time to reproduce and you lose your period. Estrogen levels also decrease to a level where bone regeneration is stunted, which can mean bone loss leading to increased risk of stress fractures and even osteoporosis.

    Mathematic example:

    Example woman:
    140 lbs
    27% bodyweight
    102 lbs LBM
    13.6 x 102 lbs = 1387 net calories would be tipping point

    I understand that but my question is that if I'm eating 1400-1700 calories a day does it matter that I have three days a week where exercise puts me at a huge calorie deficit? If just those three days are going to cause huge muscle loss then I would be willing to force myself to eat more. I am eating 20-30 calories per kg of lean mass, it's just that I have some really big calorie burn days.

    An although I appreciate you taking the time to post links they are not relevant to me or my question. My question/concern is muscle loss.
  • jtintx
    jtintx Posts: 445 Member
    VintageFeline wrote: »
    First off, starvation mode as used here is not a thing.

    Having too large a deficit consistently (this is the key here. you need to look at weekly averages) will cause your body to turn to muscle for fuel. Obly so much stored fat can be metabolised in a day, after that the body looks elsewhere.

    I'd also be curious to know what you're doing to burn 1500 calories. It would take me more than 3 hours of strenuous cardio as a 165lb woman to burn even close to that much.

    I only used "starvation mode" because I didn't want a bunch of responses about that. :smile:
  • trigden1991
    trigden1991 Posts: 4,658 Member
    jtintx wrote: »
    VintageFeline wrote: »
    First off, starvation mode as used here is not a thing.

    Having too large a deficit consistently (this is the key here. you need to look at weekly averages) will cause your body to turn to muscle for fuel. Obly so much stored fat can be metabolised in a day, after that the body looks elsewhere.

    I'd also be curious to know what you're doing to burn 1500 calories. It would take me more than 3 hours of strenuous cardio as a 165lb woman to burn even close to that much.

    This was only an example but typically to burn that many calories I play 3 hours of competitive racquetball or go for bicycle rides over 50 miles.

    How much stored fat can be metabolized in a day?

    It doesn't matter because after a few days you would feel awful, binge and put a halt to your progress.

    There are examples of people doing extreme amounts of activity with large calorie deficits for very short periods of time (2-4 days). Have a search for ERFL. This is not really the place to discuss such protocols though.
  • janejellyroll
    janejellyroll Posts: 25,763 Member
    edited January 2017
    jtintx wrote: »
    janejellyroll wrote: »
    There is a limit to how much fat your body can utilize for energy per day, so if you're regularly exceeding that with very large deficits, you'll be targeting your muscle for loss. If you're burning 4,500 calories a week through exercise and you aren't hungry, your hunger cues may not be a reliable guide to ensure you're eating enough. If you aren't hungry that night, how about eating some of them the next day?

    I do eat the next day but breakfast and lunch only amount to about 800-1000 calories before my next workout.

    Muscle loss is my concern. It seems that every time I gain and then have to lose weight I end up losing more and more muscle. I don't want to end up being "skinny-fat."

    Then you need to eat enough to ensure you aren't burning through your muscle. If you aren't hungry, try adding calorie-dense foods to your meals. Or, like @cwolfman13 suggested, look at ways to reduce your training.

    If you're already noticing the impacts in your body composition, you know things aren't working the way you're trying to do them.
  • jtintx
    jtintx Posts: 445 Member
    kimny72 wrote: »
    The real tell will be how much weight you are losing per week. Starvation mode is not a thing in the short term - you would need to have a large deficit consistently over a long period of time, and all that would do is slow your metabolism, not stop you from losing weight.

    If the info in your profile is correct, you have 35 lbs to go? You should be shooting for 1 lb per week. If you are consistently losing faster, you need to eat more. I think the healthy limit that is always mentioned is 1% of your body weight per week, but that would be the upper limit, fastest you should go. If you are prioritizing muscle-sparing, I think 1 lb would be the general advice.

    Depending on how accurate your logging is, and how inflated your calorie burns are (both of which are likely, it happens all the time!), your deficit might not be as big as it seems.

    Profile info is correct. Calorie logging is spot on based on nutrition labels and measuring/weighing food. Exercise calories are based on MFP and usually compared to other sites to verify caloric burn. Thing is I don't seem to be losing weight (other than the initial loss the first week back)...thus the hesitancy to eat back more of those exercise calories.
  • jtintx
    jtintx Posts: 445 Member
    edited January 2017

    I understand that but my question is that if I'm eating 1400-1700 calories a day does it matter that I have three days a week where exercise puts me at a huge calorie deficit? If just those three days are going to cause huge muscle loss then I would be willing to force myself to eat more. I am eating 20-30 calories per kg of lean mass, it's just that I have some really big calorie burn days.
    You didn't read and absorb what I wrote. Your energy availability is below 20-30 calories per kg of lean mass when you eat 1500 and burn 1500. You are risking bone health, which is as important as muscle. But it sounds like you are determined to eat too little and exercise too much. Do what you want. Good luck with your bone fracture goals of 2016.

    This only occurs 3 days a week. IF I was determined to eat too little and exercise too much I wouldn't be seeking help/information. Your sarcasm wasn't necessary or welcomed. I could also say you didn't absorb what I wrote.
    If just those three days are going to cause huge muscle loss then I would be willing to force myself to eat more.

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