I have been getting conflicting opinions on this, and with a quick search on Google was not able to come up with much... so, I decided I would ask y'all.

How long does it take your body to digest the food you eat, and how long before calories you eat will turn to fat?

Example: If I eat late at night and then am totally inactive overnight do those calories basically turn straight to fat, other than what my body uses for basic functions?

or...

Does the body take long enough to digest/process my food that if I do something in the next 24-48 hours like workout extra hard that it will not turn to fat.

I understand that the two above are extremes, but the conflicting opinion that I am up against is: Calories are calories and even if I/they eat 1900 calories right before going to bed and 300 all day leading up to that, that they are still fine because calorie are calories and the body takes 48 hours before extra calories turn to fat anyway.

I know this is dumbing it down a lot, but I am trying to just understand this a bit better.

(I will be away from the computer all day so will not be able to respond till tonight)

Thanks,

Tim

Also looking forward to seeing some responses on this one.

Good question Tim!

wow, did it take me a long time to find some relevant info. i believe this link may have some answers, but i don't have the time to read/interpret it myself (i'm at work!)

http://www.med.unibs.it/~marchesi/lipsynth.html

i tried a lot of keywords before i found this. it came up under "fat synthesis" on google.

btw, a lot the info in this article doesn't make any sense if you haven't studied biology in a while. this article also has a lot of useless (but interesting if you care) info about the production of fat at the molecular & cellular level.

i'm going to point out one fact before i continue. molecules of fat are not what you see in the mirror. the fat on your body is adipose tissue, or groups of fat cells. you may have a lot of fat molecules traveling around in your body that do not show up as flab. i hope that makes sense.

i'm going to take an educated guess here and say that eating food with a lot of carbs is the worst thing you can do before sleeping. i think fat and proteins are less likely to be converted into fat tissues (adipose). since insulin has a direct effect on the conversion of carbs into fat, and also the the activity of lipoprotein lipase (the molecule that regulates the import of fats & lipids into fat cells), including carbs in a late night snack/meal will probably encourage your body to store the nutrients as fat (tissue).

the useful conclusion i'm leaning towards is that you should try to exclude any carbs from a late snack. the calories in your last meal may be converted into useful molecules of fat, which possibly will not become part of fat tissues, but including carbs in your meal will make it more likely that the calories you consume will be converted to fat molecules AND stored in fat cells (flab).

i'd like to emphasize that this is statement is what i derived from the info i read. if i'm wrong, feel free to correct me.

i also took some info from this site as well -- http://www.pubmedcentral.nih.gov/articlerender.fcg i?artid=23350

Joel,

Thanks for your hard work. I am just now getting to sit down and take a look at it and it is almost time for bed for me. I will read up on it tomorrow morning.

I am glad I wasn't the only one that was having trouble finding anything about it. I didn't do much searching, but usually I find something more than what I did.

Thanks again! Will post something back in the morning.

Tim

WOW - that is a lot of information, and much over my head. I am still not sure how to make heads or tails of it.

Thanks Joel for your interpretation of what the sites are saying.

There is a lot of good information there to help understand how your body processes it.

Thanks!

Tim

Now this is not a scientific explanation in the strictest sense; however, this is how I understand the process.

Fat "synthesis" or the creation of fat in the body can only happen if there is a caloric surplus in the body.

Basically if you eat more than you expend then you can gain fat.

As far as I understand, that's pretty much the end all be all of the entire equation.

If you burn 2000 calories in a day, and you eat all 2000 calories right before you go to bed, then you still won't gain any fat. Because in that situation the total calorie excess = 0. Where would the energy possibly come from to generate any fat tissue?

Well it looks like I'm a year behind in adding a comment to this... But, I think there is more to it than just 2000 calories in 2000 calories used.

For instance, I've been running about 2.5 to 3 miles about 3 times a week. I've also been on a calorie restricted diet fairly low in carbs.

What I noticed today at lunch when I went for my run was that I had a huge amount of stamina and engergy compared to every other day I've run since I started up again after a 25 year break.
The difference in today's results, I believe, is that I pigged out on a pile of awesome french fries last night about 3 hours before bed. Felt really guilty about those fries until I had a great run today.

So my big question is how long do recently eaten calories stay in your body waiting to be used before they turn into fat. And, when is the best time to tap into those calories?

Marathon runners load up on carbs the night before running so they will have endurance.

Wish I knew the secret formula!!

I would argue that dedicating too much time and energy into thinking about this is a distraction at best and a justification of poor eating habits at worst.

Your body is burning calories constantly throughout the day, even if you are completely stationary. Your heart pumps blood and all sorts of other things happen as long as you're alive (which is a reasonable assumption if you're reading this). If you've exercised, especially weight training or other muscle building activities, then your body is also repairing itself, a process which requires calories, in addition to other nutrients. It's not a constant burn, of course. When you're actually exercising then your calorie burn goes up and when you sleep you're burning less. Some foods also take more time to process and some foods actually burn calories as they are being converted to a usable form by your body. A "calorie" is not just a 'calorie" and there is no simple magic formula to being healthy and losing weight... focusing too hard on calories is, again, a misleading distraction and can actually cause people to go the wrong direction.

Most calorie restrictive diets, especially the extreme ones, cut off many of the foods your body needs. Carbs are not the enemy, neither is fat. Your body needs carbs for several reasons (such as the energy you felt on your runt oday), and if your calorie intake is too low (which most people who go on "hardcore" diets do) your body will actually cannibalize muscle and not fat, so people can still look fat and have loose skin despite the fact that the number on the scale is dropping.

The important thing to think about is WHAT you're feeding your body so that it can be most effective and HOW OFTEN you feed yourself to offset the calorie burn. Feeding yourself in spikes (ie 2 big meals a day) tells your body to do two things: a) lower it's calorie demand for the long periods between replenishings by burning muscle and b) store whatever it can as fat so that it's got access to that potential energy during the next drought. Muscle burns calories just being in your body, fat doesn't even need water to exist in the human body so, by lowering the net burn and storing fat for energy when none is readily available, your body is becoming more efficient at what you're telling it that it needs to do, which is the opposite of what you actually want.

The general rule of thumb is to eat six times a day (3 meals, 3 snacks), but smaller portions. The analogy I like to think about is a coal engine, you can't overload the engine twice a day or it will explode. If you forget to shovel in coal, the engine dies. It has to be a constant process; but once your body trusts you to keep it fueled when it needs fuel it will stop seeing a need to store as much fat.

The last post before you resurrected the thread is, in my opinion, very wrong. If you eat 2000 calories all at once, your body will have an excess of what it needs IN THAT MOMENT and it will store that excess as fat because it won't trust you to provide for it again... your body doesn't burn all 2000 calories at once, once again, it burns throughout the day and by trying to load it up all at once you're going to be signalling your body to burn away protein (muscle) to lower it's energy demands and store fat for tomorrow's dry spell.

I didn't read the article, but basically your body operates on a supply-demand cycle. It's not so much a time frame. At any point in time, if your blood sugar is elevated, insulin is produced. Insulin is a storage hormone that will send the excess sugars first into your muscles (can store about 100 g of carbs IIRC), and then what's left over will be converted to fat and stored in the adipose tissue.

What that means is that if you eat a high GL meal in which you've eaten excess carbs and it spikes your blood sugar, you can be guaranteed some of it will be stored as fat. Also take note that excess protein has the same effect - and the protein to energy to fat conversion process produces ketones that aren't so great for the ol' kidneys.

In general, don't eat more than 30-40 g of protein at once, and keep your carbohydrates the low GL kind. This will keep your blood sugar stable and minimize fat storage. Obviously don't eat too many calories either, because that also spikes your blood sugar, duh. At night aim for about a 100 calorie snack within an hour of bedtime. This will be just enough energy to fuel your body for your long slumber without causing an insulin spike (provided the carbs that you ate wasn't a "bad" carb that digests all too easily).

hi

i have glanced your article it is interesting. i got more information about burning our calories. as per my knowledge drinking the ice cool water rebuses the calories faster... thank you for the great information

[url=http://www.burning-calories.com/]
[/url]Burning Calories

What an interesting thread with a whole range of opinions. For the record, here is my 2 pennyworth.

In a crude sense calories are just calories and it really is that simple. However, there are a whole range of factors that determine how many calories you can get away with eating and how many you can't that go way beyond the simple formulas we all cling on to for our maths. At the end of the day if your body has no use/ requirement for calories then they are stored as fat.

I think a useful thing to add now will be how your glycogen stores work.

I think that this will in part answer Joanna's query about carb loading for endurance events and how that works. Basically energy is extracted from the food you eat and stored in the muscles as glycogen. Then when you require this energy it is ready and waiting. The energy is naturally derived from the food you eat and generally speaking is from the glucose of digested carbs that is drawn from the blood by insulin (which is spiked as blood sugar rises). So this store of energy is where all your carbs go, so to speak. On the other hand, when this store gets low the opposite of insulin, which is glucagon is released into your bloodstream to break down fatty acids for energy and get energy from elsewhere, which I believe forms the basis of ketosis.

Are you with me so far? I'm trying not to get carried away with the complexity of it. The concept is actually quite simple really.

Now when this store is low, everything slows down to conserve energy, including metabolic rate and the energy available for muscles to expend for energy. So of course you will be lethargic, and over time in weight loss despite early gains, this is a bad method of weight loss. It is generally accepted that these stores are low in the morning after your body has been growing and repairing through the night. Hence the emphasis on breakfast.

For optimum athletic performance it is great to have these stores at max when you begin the event, which is what carb loading aims to do. So that answers Joannes question about stocking up in advance. Of course you can not perform if your glcogen stores are near empty. For endurance events these stores need topping up as you go as the store is not always big enough to cater for the entire event, which is why athletes sip on sports drinks with sugars and carbs held within.

The next thing to note is the body gets good at what it is used to doing. So if your body frequently hits hard sessions, it will build larger stores to house the glycogen and prepare for that. Which is why non-endurance athletes fade mid way through an event, as their body has not catered for the stores required to house that much glycogen. Similarly, if you crash diet and restrict food, your body will diminish the stores so when you do have a good feed, the glycogen has nowhere to go except into fat stores as it doesn't have the capacity to store it as fuel. And it also knows that the body will never use that much fuel anyway based on recent fuel consumption by the body.

So in answer to the question about when to eat. It is more about when is your glycogen stores low? If you haven't eaten all day and your stores are totally empty, then what you eat will ot be stored as fat until your stores are refilled. Only the energy that can not be stored is converted to fat. This is the basis of GI diets, where a steady stream of digestion never overfills the stores, so to speak. However, it has to be balanced as this will not always suit the goals and requirements of a training programme.

Recovery requires glycogen stores to be full. Growth requires glycogen stores to be full and performance requires glycogen stores to be full. While stores house the energy there is no concern of fat gain. Only if stores overflow is fat storage an issue.

Also, your stores adjust to your routine. Some people always have one big meal a day and have done all their life. If that is the case, their body will adjust to this pattern and will be prepared for the energy ingested at that time as the body knows the pattern. Sometimes you see people doing completely the wrong thing but getting good results. This is often simply because they are consistent, and the body gets good at what it is used to doing. It is an art to get the balance right between routine and keeping your body guessing. Tricky, but worth getting to understand your own body.

So in essence calories are calories, so long as your glycogen stores have room for the energy.

I hope that I haven't lost anyone here, and that this very crude understanding is of some use to you guys.

Keep up the Intensity!!!

Yep, that is exactly what I was trying to say. Insulin, your "storage hormone" will attempt to store in your muscles (glycogen) first, then what's left over (assuming your blood sugar level is still too high for your body's taste) gets stored as fat. Your body likes to maintain a certain level of blood sugar for nueral / brain activity. In fact, your brain is the biggest glucose hog in the body. When your blood sugar gets low, there isn't an adequate food supply for your brain, which is one reason why you feel foggy / sleepy.

So in short, in order of importance, 1) feed your brain, 2) store the excess in your muscles, 3) store what's left as fat.

That is a great read Dean.