Wierd question: How does your body measure "time" in regards to calories?

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ISeeNoChanges

New member
This may sound like a weird question, but it is something i have wondered about for a while. (I'll admit that I am an Engineer and am not at all surprised about my mind wondering about this...)

Most people agree that weight loss can be simplified as Cals In vs Cals Out (i know it is much much more than than, but im simplifing here)

For my mind to make sense of this i almost need to associate a time frame with it. Is this per sleep cylces? Per 24 hrs? per Week? etc?

Just for example consider the following


Day 1
Cals in 1500
Cals out 2000
Day 2
Cals in 2500
Cals out 2000
Day 3
Cals in 1500
Cals out 2000

So this is a 3 day net of -500 (aka weight loss), but i often wondered about what time frame your body uses to determine when it takes nets?

Im curious to hear what the pro's have to say. Do we know what time frame our bodies are on in determining nets?

Leave it up to an Engineer to try and bring logic into weight loss... Sorry!

Interested to hear your thoughts?
 
I have thought about this also and the way I think about it is like a car. You put petrol in and the activity you do in the car requires fuel. The more activity you do in the car the more fuel you burn.

In terms of our bodies they are constantly burning calories every minute of every day even just sitting there watching TV or sleeping. The body is running so many processes with regard to keeping you alive and regeneration of cells etc it never stops.

People work out how many calories they will need for a day (24 hours) so that they do not over feed themselves. You could equally work out how many calories you need for a week, a month or a year but its not really practical.

The truth is you could get up in the morning and eat nothing and work out for a couple of hours and you will be -1500 calories, that is if you are working on a DAILY allowance of calories. Where our bodies differ from cars is that we store energy that we can use at a later time. The energy you burn in your morning workout could be from food you ingested yesterday...

The trick is to try keep it balanced. Rather than fuel up in the morning on 2500 calories and then try live off it for the day it makes more sense to spread that out throughout the day.

A great way of considering calories is to think of 1lb of fat being equally to roughly 3500 calories. If you are over eating and storing these calories on your body... for every 1lb of fat you have stored you are going to have to burn 3500 calories more than your body uses in its day to day operation. Every time you burn 3500 extra calories you will drop a lb (in theory). This could take a week a month or a year...

Interesting thread by the way :)

EDIT: just re-read your original post and realised I never mentioned when your body calculates the NET calories used. The short answer is it doesnt. Your body burns these calories in real time. If you burn off 1000 calories you have burned off 1000 calories. Go back to the car analogy. If you put 10 gallons of fuel in your car your car doesnt decide when the 10 gallons is gone the mileage you do dictates when it goes. If you kept filling your car up with more fuel and you never drove anywhere it would get full and you you would have to start adding extra containers to hold what you were putting in to it. You could start driving one day and not put any fuel in it and use up the extra you stored when you over filled it.
 
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Your body is rarely at '0 net' - and it's in fact in a state of constant integration. The exact details depend on what foods you ate and how your body processes them and how many calories you're burning at that point in time. However, the best way to look at is that you're integrating the area under the curve for the period of time you're interested in. Since weight loss generally takes weeks or months, then a weekly average or even a monthly average is perfectly legitimate.

In your example, you're down 500 calories over 3 days - or about 2 oz. That's still weight lost overall, but the scale won't exactly match that in terms of pounds (or ounces in this case) but long term that's what matters. You can eat over maintenance for a day and 'make up' for it on other days if that's what you want. In fact, there's a philosophy of dieting that alternates between surplus and deficit days, trying to have surplus on strength training to build muscles and deficits on other days to burn fat.

In a more specific sense of 'body timing' I've heard that there's a 24 hour window after a strength training workout where your body is more inclined to gain muscle - eating at a surplus after that window won't net you as much muscle per pound (or calorie surplus) gained. Meanwhile, there's a muscle preservation effect that lasts around 5 days after a workout - you're less likely to lose muscle while in a deficit for 5 days after a strength workout. (I think - I admit I am loosely basing this on the general recommendations of how often you need to workout, plus the 'no more than 5 days between strength training a muscle group or you'll lose strength' rule).

As you can see, the timing is different - however unless you're trying to directly work with these smaller cycles of deficits and surpluses it's perfectly fine to just consider the average over the period you're interested in.

If I eat 1200 calories 6 days out of the week and then pig out and have 4000 calories on the 7th... The average of 1600 calories a day over the week would still work out to a deficit and therefore weight lost for me.
 
Thanks for your reply. I have thought of the car analogy as well. The problem my mind has with it is that a car tank can only hold so much, while our bodies will "keep adding tanks" as you put it.

I have been on a diet and exercise program for about 8 months with great results. The summer months and their weddings, vactions, parties, picnics, etc. have me on a very healthy monday-noon on friday routine and a not-so-healthy noon on friday to sunday routine.

Yes, i know this is bad, and i do try to limit the excess, but i know im un-doing alot of my hardwork with it.

Would you say it is as simple as this?

I want to burn (for example) 10 lbs (35,000) cals over an unknown time.
Day 1
-1000 cals
Day 2
-1000 cals
Day 3
-1000 cals
Day 4
-1000 cals
Day 5
-500 cals
Day 6
+2000 cals
Day 7
+2000 cals

So in 7 days im a net -500 cals or 1/7th of a pound... again, it brings me back to the time frame
 
you are pretty much doing what I am doing and what the other member that posted above is. It is working for me so I dont see why it wont work for you.

Of course there are variables like how much exercise you manage to get in during the week as it may fluctuate from week to week so overall may give you different results. But in basic terms...

If you burn through 2000 calories a day that is 14,000 a week. If you consume less than 14,000 in a week you will burn more than you consume and so will lost weight.

My aim is to create a significant deficit in calories and add in significant exercise. I am probably around 1400 calories a day, which for me is fine at the moment as I go through phases of eating and not eating much. I am doing a minimum of 25 miles a week which is about 2600 calories. Without counting every little thing I eat it is pretty obvious that my body is using up far more energy than I am supplying it with food and so I am losing weight.

I try not to be over analytical with these things as they begin to feel a bit regimental so I am just following it loosely.

I used to weight train a lot a few years ago and back then I would be very careful about how I ate and when I ate. As mentioned above it is widely believed that their is a good time to consume protein after working muscles for growth and repair. I must admit it was hard work simply trying to consume enough food. It makes losing weight seem easy in comparison.
 
You say you're an engineer, right? well think of it like this. Calories burned is a rate. dC/dt, basically. You integrate dC/dt, as jeanette explained. Its a continuous integration, not a 'delta' C / 'delta t' summation. So the time frame can basically be whatever you want. Whenever the total of the calories you eat for any time frame is greater than the integral of the calories burned for the same time frame, your body stores energy, and vice versa.

If you eat a 500 calorie meal and your body takes an hour to digest it, its unlikely your body will use all those 500 calories right away - some of it will be stored. But 2 hours later when you're in between meals, you're body is still burning energy, and if it has no food to digest, it will pull from the stores.

You can think of a time frame as a limit. Just as an example, you might need 100,000 calories in a month, but if you eat 100,000 calories the first week and 0 the next 3, its not going to be very healthy. You never want to be in a deficit of more than 30%, at least not for very long - your body quickly begins to adapt to a larger deficit (starvation response), and you're likely to lose muscle mass. Plus, just guessing, but there is more to it than calories - I'm sure there are some micronutrients that your body needs to intake daily that aren't stored if you take in extra, just passed out of the body as waste.

All this being said, I wouldn't put that much thought into it as others have said. There are diet plans such as Intermittent Fasting that is as aggressive as zero intake 1 day and double intake the next. Eating larger meals in a surplus on the weekends while still in a weekly deficit can delay or prevent the bodies starvation adaptations to a calorie deficit. I think a weekly average is fine if done as you describe above, but it wouldn't be healthy if an individual tried to eat a week's worth of calories on monday and then didn't eat again until the next monday.
 
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