Wildly different TDEE/BMR results from different sources

csy108
csy108 Posts: 58 Member
in Health and Weight Loss
I apologize because this post is somewhat duplicative of others, but I'd like some specific advice on this topic.

I'm 5'9", 244, male, 31yo. Based on my appearance, and the YMCA and Navy measurement methods, I believe my BF% is between 42-45% (corroborated by a scale with electric current BF% estimation), so I'm using 44% in TDEE calculators. I started using MFP seriously on April 21st and have educated myself a great deal since then on creating a calorie deficit. I wanted to start using a TDEE method after hearing how many people believe MFP greatly overestimates calories burned by exercise. However, I have received wildly different results (using light exercise, 1-3 hrs per week):

Mifflin-St. Jeor (IIFYM.com): 2,825 (Scoobysworkshop.com): 2,826
Harris-Benedict (IIFYM.com): 3,105 (Scoobysworkshop.com): 3,095
Katch-McCardle (IIFYM.com): 2,353 (Scoobysworkshop.com): 2,353
Cunningham (Scoobysworkshop.com): 2,566
Fat2Fittools.com 165lbs goal weight calorie intake: 2,421

I am committed to the proposition that the sole factor in my loss of fat and lean muscle will be my calorie deficit. To ensure that it is mostly fat, I am eating a lot more protein than in the past and doing a weight routine, albeit a pretty meager one, and using an elliptical for some of my exercise for the first time in my life. Now, how can I figure out my TDEE? The numbers I got from those calculators are so insanely different that, for instance, Fat2Fit purports that maintenance at 165 will be almost 100 calories more than the Katch-McCardle formula says I need for maintenance at 244lbs.

Temporarily I'm aiming for 1,900 calories intake per day, but any advice on where to set my goals and how to proceed with adjusting that target would be appreciated.

Replies

  • weird_me2
    weird_me2 Posts: 716 Member
    Well, I'd knock out the Mifflin St Jeor and Harris Benedict equations off the top because they are not based on body fat % at all. On the others, I'd say they are close enough in number that I'd go with the average or middle number...around 2450 calories. If you are on the Scooby website and click on the icon by where you choose the equation type, they will tell you how each equation figures the caloric goals if you want more info about each formula.

    If you've been keeping a detailed and accurate log of your intake, you can get a pretty good estimate of your TDEE by taking your average intake for at least a month and then adding or subtracting calories based on whether you've gained or lost. This is only going to work if you keep an accurate and detailed log consistently, though. I just did this today and came up with a TDEE that's pretty close to the Scooby Katch-Mcardle number.
  • EvanKeel
    EvanKeel Posts: 1,904 Member
    I haven't checked your math for those equations. But based on my own experiences, for whatever that's worth, I'd probably start out putting your TDEE at around 2500ish, knocking off 20% would put you at 2000 cal per day. So 1900 per day seems reasonable.

    All of the estimating in the world, though, is not going to be at useful if your logging is inaccurate. If your logging is accurate, you can adjust your numbers over time based on what the results are. It's all kind of a process of trial and error in the end.
  • csy108
    csy108 Posts: 58 Member
    Thanks for the input. I've been extremely detailed in my logging so far. Perhaps not perfect since there is some eating out, but I would be truly shocked if I am outside of 100 calories on any given day. I'm using a food scale and being neurotic about it (not guessing or eyeballing stuff), because I have never, ever tried to create a calorie deficit before and I had literally no real concept of how many calories were in certain foods at certain volumes.

    I guess I had a little bit of a fear that eating too few calories (like a 1,000 calorie deficit, if my TDEE really was around 2,800) would be detrimental, causing me to lose lean muscle. I only have two weeks of data right now, but I will adjust at the one month mark based on my own findings.
  • vismal
    vismal Posts: 2,463 Member
    I wouldn't worry about it. All those equations are merely estimates. Pick any one of them and use it as a starting point. If you are not losing weight at the rate in which you would like, reduce total calories. Don't get caught up in a million numbers. The keys to fat loss are eating less and moving more. Whenever fat loss stops, just eat less or move more.
  • EvanKeel
    EvanKeel Posts: 1,904 Member
    Thanks for the input. I've been extremely detailed in my logging so far. Perhaps not perfect since there is some eating out, but I would be truly shocked if I am outside of 100 calories on any given day. I'm using a food scale and being neurotic about it (not guessing or eyeballing stuff), because I have never, ever tried to create a calorie deficit before and I had literally no real concept of how many calories were in certain foods at certain volumes.

    I guess I had a little bit of a fear that eating too few calories (like a 1,000 calorie deficit, if my TDEE really was around 2,800) would be detrimental, causing me to lose lean muscle. I only have two weeks of data right now, but I will adjust at the one month mark based on my own findings.

    Given your BF%, I wouldn't worry about that deficit contributing to lean muscle mass loss. However, if that is a concern, I would strongly suggest adding some lifting to your routine if you don't already.

    As you get leaner, you may want to reduce the deficit a bit, but for a point of reference, I have some pretty muscled friends who cut on 2000(ish) calories a day. I have some pretty severe hunger issues if I go below 2100-2200 calories.

    EDIT: I'd also suggest eating a decent amount of protein.
  • rbiss
    rbiss Posts: 422 Member
    No matter the calculation, they will all be a little off. Take your best guess, see how much weight you loose, and back calculate your total needs. I would do this over 3-4 weeks to get a good average and recalculate every 10-20lbs based on how fast your loosing. If you notice your loss slow down, drop the calories a little.
  • AmyRhubarb
    AmyRhubarb Posts: 6,890 Member
    I agree with picking one and going with it - preferably one that takes BF% into account. Stick with it for 4-6 weeks, make changes if needed.

    Side note - I used the Fat2Fit tools, but rather than entering my goal weight to get my future TDEE, I entered my current weight into that box, to get my current TDEE. Every time I lost 5lbs or so, I'd rerun my measurements and numbers and make adjustments if needed. It's worked great for me for the past 2+ years, and still going strong. :smile: Good luck!
  • awesomek001
    awesomek001 Posts: 167 Member
    I haven't checked your math for those equations. But based on my own experiences, for whatever that's worth, I'd probably start out putting your TDEE at around 2500ish, knocking off 20% would put you at 2000 cal per day. So 1900 per day seems reasonable.

    All of the estimating in the world, though, is not going to be at useful if your logging is inaccurate. If your logging is accurate, you can adjust your numbers over time based on what the results are. It's all kind of a process of trial and error in the end.

    I agree - - pick a point and start there. Tweak from that point based on what works for you (since no one else is exactly like you). I've found that it's trial and error the whole way. As your body evolves / changes, what worked before doesn't work now (maybe because your body gets used to it). I've been tracking for quite some time (4+ years), and it's amazing what I find when I look back over the information and compare results.

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