Help! Backing into your base metabolic rate using MFP data

rynathan

Ok someone please let me know if I am missing some thing here?

I looked back at the past 75 days of MFP data. Added up all calories consumed, subtracted all calories spent on exercise, and then came up with a net daily caloric intake of 58k, or 770 calories per day (yeah, a little low, but I worked out a lot).

In this period I lost 16 lbs. @ 3,500 calories a pound, that represents a caloric deficit of 56k calories, or 747 per day

That would seem to indicate that my natural resting metabolic rate is a measly 1517 calories per day!

Ok, let's say I put on some muscle in this time as well. Let's assume 8 lbs (I wasn't lifting weights, all exercise was running and cycling, so can't believe it was any more than 8 lbs). I understand that 1 pound of muscle requires about 1750 calories, so let's say this required an additional 13.5k calories, or 181 per day.

That makes my resting metabolic rate still only about 1,700 calories a day. I am a very active 5'8', 37 year old male who now weighs 161 lbs. Most basal metabolic rate calculators say my base consumption should be about 2,200 calories. Can anyone point out any flaws in my logic?

Thanks,

- Ryan

sunraze

Not to be a goofball or anything but is it possible that you could have overestimated calories expended? Not all methods are exactly accurate. Also maybe you forgot some little bits of foods here and there? Adds up. Don't overthink the whole thing. Losing weight is not a mystery--eat less, exercise more. I seriously doubt that is your BMR. Look how well you did during that time! Awesome.

gmrgirl

I think the first flaw in the logic is the definition of "Basal Metabolic Rate". your "Basal Metobolic Rate" is the amount of calories you would burn if you were laying in bed, doing nothing, just breathing. It doesn't include tossing and turning or anything else - just laying in bed, supporting life.

So you're saying you burn 1500 cal(approx), laying in bed doing nothing. this isn't bad given your weight and age.

Secondly, if you're not doing some sort of resistance training (bodyweight or weight lifting) you're not going to build muscle. Some cardio will help you maintain what you have, but it will not ADD muscle, for that, you need resistance training of some sort (body weight, bands, pushing metal, functional training, crossfit etc). Assuming you build easily (like one of my clients) a gain of 8# is normal for 3 months of resistance training where you are working to overload or fatigue 3x/wk. If you do not build easily (like me) 2-5# is more likely

Now, the calculators that are telling you what you should consume are saying "Lets take this person's BMR and multiply it by their activity level and tell them how much they should be eating."

So.... To give you the WHOLE calculation... here you go: to manually calculate your OWN BMR (Basal Metabolic Rate)

Men: Basal Metabolic Rate (BMR) = 10 x weight (kg) + 6.25 x height(cm) – 5 x age (yrs) + 5

Women: Basal Metabolic Rate (BMR) = 10 x weight (kg) + 6.25 x height (cm) – 5 x age (yrs) – 161

(to get your weight in kg, just divide your weight in pounds by 2.2, it's close enough. To get your height in cm, just type it into google (ie: 5'5" in cm) it'll come up)

now, if you want to find out how those calculators are getting those numbers they toss out at you, take your BMR and multiply it by your activity level

1.2: Sedentary: sitting at a desk all day, taking the elevator rather than the stairs, parking as close to the building as possible, doing no fitness activity

1.375: Lightly Active: light activity 1-3 days a week, walking a total of 2 hours a day, doing some sort of fitness for a total calorie expenditure of 590 calories a day (taking the stairs + parking further away + 30 minutes on the elliptical/treadmill at a moderate pace may meet these requirements)

1.550: Moderately Active: moderately exercise 3-5 days a week, walking a total of 3 hours every day, doing some sort of fitness for a total calorie expenditure of 870 calories a day. This can be a moderately intense workout for 30-45 minutes as well as taking the stairs, parking further away.

1.725: Very Active: hard exercise 6-7 days a week, walking a total of 4 hours a day, doing some sort of fitness for a total calorie expenditure of 1150 calories a day.

1.9: Extra Active: very hard exercise and a physical job, walking a total of 5 hours a day, doing some sort of fitness for a total calorie expenditure of 1580 calories a day.

So, lets say your BMR is 1517 and you are "Very active" meaning you do VERY HARD exercise 6-7 days a week and burn approximately 1150 cal/day *on top of* what you need to survive.

you would take your BMR (1517) and multiply it by your Activity Level (1.725) to get a total of 2616 (2617 if you round up) to *maintain* your current body weight. If you want to lose, you need to eat less.

Does that make sense?

rynathan

gmrgirl, true, I was mixing definitions (BMR vs. target daily caloric consumption). And thanks for the background on the target consumption calculators, that is very helpful.

My fear is that I just have a very slow metabolism. Which I think the MFP data proves. My true BMR, according to your formula should be 1633. Taking exercise out of the equation, so "sedentary" for purposes of the calculation ... that puts me at about 2,000 calories per day (before exercise).

The MFP data indicates that over the past 75 days I consumed a net of ~750 calories a day, and lost the equivalent amount of fat equaling to ~750 calories per day for a total theoretical net daily caloric rate of 1,500 per day. If my "base calorie consumption rate before exercise" really were 2,000 over this time, in theory I should have lost another 11 lbs ... (75 days x 500 calories a day / 3500 calories per pound of fat).

My conclusion is that I just have a slow metabolism and that I need to stick closer to a net of 1500 calories per day vs. 2000. Which is kind of a bummer!

My whole point in this exercise is that I am more or less at my ideal weight, and I am trying to figure out how many calories I need to consume to maintain it (again, taking exercise out of the equation). Of course trial and error will work to ... but trying to come up with an educated guess first!

Best,

- Ryan

gmrgirl

somethings to remember about metabolism:

- the body is efficient. it will only do what it has to. if you weigh less, you burn less because you need less energy to support your body.

- muscle is inefficient for the body to maintain. it takes a lot of energy, so if you are not resistance training, your body will break down muscle to make itself more efficient. This will slow your metabolism (a little bit, but a little bit over time adds up)

- If you wish to remove exercise from the equation, then yes, you are correct, you will need to adjust your intake appropriately.

it sounds like you have your educated guess, now you just have to go from there and decide what you want to do with it.