Is there a limit to the amount of calories the body can store as fat at any one time?

October 9, 2006 8:50 PM

Is there a limit to the amount of calories the body can store as fat at any one time? My question is, let's say you go over your caloric needs by 4,000 on one day. Does that mean that your body will add 4,000 calories worth of fat? Or is there any limit to the amount of fat the body can store in one sitting?

(Secondary question: how does one post anonymously on metafilter?)

posted by mintchip to Health & Fitness (12 answers total)

form to post question anonymously
posted by neda at 8:52 PM on October 9, 2006

You will poop it.
posted by Ambrosia Voyeur at 9:02 PM on October 9, 2006

For most people, most of the time 3500 calories=1 pound. So if you go over your caloric needs by 4000 calories you should expect to gain a little more than a pound. However, there are a gazillion factors (type of calorie, presence of fiber, hormones in the body) that modifies this relationship somewhat.
posted by Tallguy at 9:09 PM on October 9, 2006

My understanding is that your body can only process about 10,000 calories a day. Enough for the average person to gain a couple of lbs, but a potential problem for touring cyclists (for example). I'll try to find a reference.
posted by crabintheocean at 9:10 PM on October 9, 2006

This is completely unscientific, but during The Fat Project two people struggled to gain one pound per day for one month. This could indicate that the body has difficulty processing much more than 3500 calories over baseline. Or that they just had difficulty finding ways to cram down the appropriate foods.
posted by Humanzee at 9:14 PM on October 9, 2006

In studies where caloric intake and expenditure were tracked over long periods of time, it has been found that there is little correlation between calories used and calories ingested on a day-to-day basis, but the correlation was much higher over spans of several days. This would seem to suggest that gorging on food one day will result in reduced appetite, and therefore lower consumption over the next few days.
posted by Maxwell_Smart at 9:15 PM on October 9, 2006

Ha. I got that right here. I copied randomstriker's post almost exactly. Sorry (and thanks!).
posted by crabintheocean at 9:16 PM on October 9, 2006

I'm under the impression that while there isn't a limit on calories, that there is a limit on how much your kidneys and liver can process over time; I know that very obese people occasionally encounter organ problems as a result. So i guess that's a limit of some sort...
posted by Kololo at 9:56 PM on October 9, 2006

This also depends highly on your metabolism, and, most recently discovered, possibly the bacteria in your gut that help determine how efficiently you absorb calories.
posted by gramcracker at 10:37 PM on October 9, 2006

There's a limit to what your intestines can absorb. The Nathan's hot dog guy eats 53 hot dogs, that's about 13,000 calories right there, he does NOT immediately gain four pounds of fat, because his system simply can't process that much that fast.

One of the things the hormone progesterone does is slow down the processing of food through your intestines, so that pregnant women can absorb more calories from the food they eat. (Which leads to a lot of flatulence and constipation, but hey, small price to pay for being able to get enough nourishment to feed your baby.)
posted by jellicle at 5:15 AM on October 10, 2006 [2 favorites]

Fat storage is a complicated process. An enzyme called Acetyl-CoA Synthase is what makes fat from food you eat. This enzyme is activated by insulin, which in turn is released in response to high blood glucose concentrations that occur when you eat a lot of carbohydrate-rich food. The ACC enzyme is inhibited by epinephrine and glucagon, which are present when you have low blood sugar levels. ACC is also inhibited by the presence of fatty acids such as palmityl-CoA, which means that fat intake can inhibit fat synthesis. That's the idea behind low-carb diets. Eating mostly protein keeps your blood sugar from rising, which keeps insulin low. Eating fat with the protein provides calories and also inhibits fat synthesis and storage while promoting fatty acid metabolism.

So a high intake of calories, by itself, doesn't necessarily result in fat storage, rather it's the degree to which the calories ingested raise blood sugar levels.
posted by Mr. Gunn at 7:40 AM on October 10, 2006

If you wish to study the effects of long-term very-high-calorie intake you should consider reading up on how sumo wrestlers bulk up: what they do does boil down to 'eat lots and lots of food each and every day', but it's not quite so simple as that.
posted by little miss manners at 8:12 AM on October 10, 2006