BMR and TDEE: questions and such

recoveryjunky
recoveryjunky Posts: 162 Member
in Health and Weight Loss
I've been following MFP's calorie suggestions for about two months. I've lost about 16lbs. Not bad! But I've been doing some research on BMR and TDEE -20% and those numbers are WAY different than what MFP suggests to lose weight. Like 1300 calories VS 1800 calories.

So a couple questions:

BMR is what your body needs to do basic functions and live, right? So if that is so, is that the LOWEST amount of calories I can consume? Or do I still have to create a deficit? I can't wrap my head around what is right here...

If I change to doing 1800 calories/day, which I am going to do at least for a short time to see if I lose as well with that, how long should it take to see differences? A month? Two? Also, am I going to see some water weight because I will be eating more?

Any suggestions, advice, answers, anything would be appreciated :)

Replies

  • ZUMBAMomma84
    ZUMBAMomma84 Posts: 61
    I'm right there with ya. Trying to figure out what to set my cals at. I have 1661 bmr and 1958 tdee.
  • RichardFL
    RichardFL Posts: 44
    BMR is definitely the lowest amount of calories you should consume for any extended period of time. Intermittent fasting and some other plans might have you under BMR for a couple days at a time, but you shouldn't stay under for weeks at a time or anything.

    If you make relatively minor changes (like 500 calories a day) you want 4-8 weeks of data before deciding if it had the intended effect. 500 calories a day is only a pound a week, and scales just aren't accurate enough to know if the pound is from what you did or just water retention or whatever else.

    Water weight, glycogen levels and such are based on your diet, your activity level, and even your genetics. If you do gain weight by increasing your calories by 500, it should be temporary since you have 2 months of data showing you were running a 1000 calorie daily deficit. So increasing by 500 should still be running a 500 deficit (1 pound a week).

    Just make sure you have the right expectations for TDEE-20. You will lose weight at a slower pace.
  • jacksonpt
    jacksonpt Posts: 10,413 Member
    They shouldn't be that different when you look at the bigger picture. If they are, you're doing something wrong.

    MFP will have you eat less on rest day, more on workout days. TDEE will be the same each day regardless of workouts. So in time it all averages out and you should end up eating about the same regardless of the approach you choose.
  • recoveryjunky
    recoveryjunky Posts: 162 Member
    Well I know how to do math and how to input my height and weight into mfp lol I'm pretty sure I didn't do it wrong ;) I read on here somewhere that if it was way off (which happens on here) you should go with your BMR, I just needed to figure out how to do it :) thanks for the replies!
  • Mokey41
    Mokey41 Posts: 5,769 Member
    You should never be eating under your BMR. MFP will give you a budget down to 1200 calories based on what you input as you goal but it doesn't care if that number is under your BMR. It assumes you know not to go that low. If it's giving you a number under your BMR then you need to pick a less aggressive goal.
  • recoveryjunky
    recoveryjunky Posts: 162 Member
    You should never be eating under your BMR. MFP will give you a budget down to 1200 calories based on what you input as you goal but it doesn't care if that number is under your BMR. It assumes you know not to go that low. If it's giving you a number under your BMR then you need to pick a less aggressive goal.

    You know, that is EXACTLY what I needed to hear. Thank you :) I wish they would say that explicitly when you sign up... I only used the app for probably the first monthish and there isn't much info on there
  • onwarddownward
    onwarddownward Posts: 1,683 Member
    I think it's important to realize that both of these rates are estimates. Your real rate is unique and will change day to day and with every drop in weight. It's constantly in flux.

    Having said that, I've changed from eating a very low net to sticking to my estimated TDEE minus 20%. I feel much better.i was starving before.

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