Can we settle this calorie debate???

OP, I'm an engineer. So, in our world, two and two equals four. Every time. No matter how large the numerals are, no matter if you used a pencil or a calculator, no matter what. It's four. Unfortunately, this site must also adhere to that law, but our bodies do not. Sometimes, it's 3.9; others it's 4.1.
Did you REALLY burn 600 or was it 596 or 604? Did you REALLY eat 1500 or was it 1490 or 1510?
Yes, this site is a good guide, a good indicator to follow for the AVERAGE person, if such a person exists.
Since I have a bad back, I didn't have to worry about eating back the exercise calories because I couldn't exercise.
Just follow MFP's guidelines and you'll be OK.
But recognize the fact that they are simply guides and not laws.

TL;DR:
Pick a number. Any number.
Suggest 80% for walking/running/cycling.
Less (even 50%) for other activities that are not as easily measured and extensively researched.
Eat that number back.
Use a spreadsheet.
Compare your expected and actual results over time.
Adjust.

Longer answer:
Variables: how well you log your food; how close to average your body is when it comes to using energy; how well you record your exercise; what percentage of your weight loss or gain is water, fat, or lean mass.

"Definitive answer": In order to maintain your target deficit (given an accurate calculation of food intake) you should eat back the actual "additional" calories you spend exercising.

How can you know that amount ahead of time? You can't! Heck, you probably can't even know it after the fact because both your actual weight changes and your body composition changes are unknown too.

If you weigh in at 200lbs today, after eating our last night, did you maintain a 3500 calorie deficit this past week given that you weighed 200lbs a week ago? How about if you also weighed 200lbs 14 days ago?

Answer is quite likely yes. A 2lb overnight gain is easy enough in response to a single meal out.

So what does one do?

One evaluates their MFP settings (sedentary, lightly active, active) and considers their daily movements and exercise regime.

Sometimes truly sedentary people add exercise and eat back calories before meeting the upper bounds of the definition of sedentary (about 45 minutes of movement or 5000 steps a day). Their weight loss stalls.

More often people who are highly active (2.5+ hours of movement and 15000+ steps a day), think they are being brilliant by calling themselves sedentary, not eating back their exercise calories, and losing weight faster.

The result tends to be excess lean mass lost and generally speaking additional adaptive thermogenesis which, over time, reduces the amount of energy expended for a given quantity of apparent effort and reduces the effectiveness of the apparent caloric deficit.

So, really, all you can do is be fairly consistent in terms of how you calculate CI and CO, and figure out over time how your body is reacting to your assumed/purported deficit.... and adjust based on your own experience

You can create your own spreadsheet to track your weight loss.
You can use some of the tools that have been created by @heybales and @EvgeniZyntx.
Or you can use or modify the following more basic spreadsheet I cobbled together: https://docs.google.com/spreadsheets/d/1VDmqNpLPu7sbQSochUJNXdp2F7AN15AGgkvS3zLw1GU/edit?usp=sharing

Motions28 wrote: »

I'm a math teacher. It drives me crazy there isn't a set answer to this....a yes or no would be fantastic. I've been doing this for 50 days and have lost 11.5 pounds so things are moving in the right direction. I just want to know if what I am doing is causing my body harm. I don't plan on staying at this once I reach my target weight...but it seems like the consensus is to eat half workout cals back. I'm never going to be hungry...

If you're a math teacher, you should be well equipped to figure this out for yourself with data you have but some of which you haven't given us.

11.5 lbs in 50 days is just over a pound and a half a week (1.61 lbs/week). At approximately 3500 calories per pound, that means you are averaging a roughly 800-calorie daily deficit (805).

The first thing you can do with that information is calculate your TDEE, assuming you've been logging your food. (Add up all your intake calories, divide by 50 and add 800. Hopefully as a math teacher you didn't need me to tell you that, but there's the method for lurkers.)

The second thing you can do is decide whether you should be eating more. We can't tell you, because you haven't told us your weight, height, and body fat %. You don't want your deficit to outpace your body's ability to make up the deficit by breaking down fat, so that you sacrifice more lean mass than is necessary or force your body to start deprioritizing things like skin repair, immune system, etc. The biggest number I've seen for the limit on calories recoverable per pound of fat per day is just over 30. Personally, I would want to be more conservative than that--by which I mean assume 25 calories per pound of fat or even 20 calories per pound of fat--because it's not likely you're consuming your calories perfectly in sync with when your body needs them throughout the day. If you don't know your body fat %, you could get expensive lab tests done to determine it, or just try to get an estimate (here again, I'd go with a conservatively low estimate for this purpose) from multiple caliper and impedance tests and by checking out pictures of people with different BF% and comparing them to your own body. Once you know your BF%, you should be able to figure out how many pounds of fat you have, and how large a deficit you want to run to try to maximize fat loss and minimize lean mass loss. (Lurkers: multiply BF% by body weight and divide by 100 to get your current pounds of fat. Multiply that result by .3, or .25, or .2, or however low you want to go to be conservative. That would give you your daily deficit goal.)

Finally, subtract your deficit goal from the TDEE you calculated from your own data, and you have your daily calorie goal. Don't adjust for exercise, unless you do something much more than what you were doing during the original 50-day data period -- i.e., you take up marathon training when you were only doing 20 or 30 minutes of cardio a few time a week during the data period.

The beauty of this approach is that it doesn't matter if the exercise calorie estimates you were using during the data period were inflated or not. It doesn't even matter if you were estimating your food intake instead of weighing solids and measuring liquids by volume, so long as you were reasonably consistent in your estimating (consistency does not equal accuracy) and continue to be reasonably consistent as you go forward.