# How fast do extra calories convert to weight gain? **URL:** \ **Category:** Factual Questions\ **Created:** [August 3, 2008, 7:06pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726 "2008-08-03T19:06:45Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![DeadlyAccurate](https://avatars.discourse-cdn.com/v4/letter/d/ac91a4/32.png) [@DeadlyAccurate](https://boards.straightdope.com/u/DeadlyAccurate)\ **Post date:** [August 3, 2008, 7:06pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/1 "2008-08-03T19:06:45Z")
For simplicity’s sake, let’s say I ate exactly 3500 more calories today than my body needed, but the rest of the week I had precisely the calories needed. When does that extra one pound show up on the scale? ---
**Author:** ![Duck\_Duck\_Goose](https://avatars.discourse-cdn.com/v4/letter/d/50afbb/32.png) [@Duck\_Duck\_Goose](https://boards.straightdope.com/u/Duck_Duck_Goose)\ **Post date:** [August 3, 2008, 8:08pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/2 "2008-08-03T20:08:47Z")
Speaking anecdotally, in my case, the morning after the 3500 calorie pigout. [sigh] [MadSci](http://www.madsci.org/posts/archives/2005-03/1112145910.Gb.r.html) is reluctant to give a hard and fast figure, because there are a lot of variables involved, but after considerable hemming and hawing, allows as how… > [@](#): > > With this in mind, fat can be formed at approximately 5 to 8 hours, on average, from the start of a meal. ---
**Author:** ![d0nk3y](https://avatars.discourse-cdn.com/v4/letter/d/f6c823/32.png) [@d0nk3y](https://boards.straightdope.com/u/d0nk3y)\ **Post date:** [August 3, 2008, 8:11pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/3 "2008-08-03T20:11:07Z")
It varies on several things, such as metabolic rates, age, hormones, and types of foods, etc. ([cite](http://www.madsci.org/posts/archives/2005-03/1112145910.Gb.r.html)) Fat can be formed about 5-8 hours after a meal. 😉 ---
**Author:** ![d0nk3y](https://avatars.discourse-cdn.com/v4/letter/d/f6c823/32.png) [@d0nk3y](https://boards.straightdope.com/u/d0nk3y)\ **Post date:** [August 3, 2008, 8:12pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/4 "2008-08-03T20:12:55Z")
hehe… I admit defeat… ☹ Sorry I didn’t refresh. ---
**Author:** ![DeadlyAccurate](https://avatars.discourse-cdn.com/v4/letter/d/ac91a4/32.png) [@DeadlyAccurate](https://boards.straightdope.com/u/DeadlyAccurate)\ **Post date:** [August 3, 2008, 8:26pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/5 "2008-08-03T20:26:20Z")
Thanks for the prompt responses. I never would have guessed it could be so quick. ---
**Author:** ![Otara](https://avatars.discourse-cdn.com/v4/letter/o/a88e4f/32.png) [@Otara](https://boards.straightdope.com/u/Otara)\ **Post date:** [August 3, 2008, 10:16pm UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/6 "2008-08-03T22:16:13Z")
That cite doesnt really cover the main question, ie is there a threshold on how much you can gain, eg if you eat say 10000 excess calories in one day, will you weigh 3 pounds more by the end of digestion/elimination, or will some certain amount go unused in some form because the body simply cant convert more than a certain amount of energy to fat at one time? The body is extremely efficient but Im not convinced its limitless. My impression is theres a gating effect and your body can only absorb so many calories in fat at one time, but Ive never seen it written about. Is the body really 100% efficient at converting excess calories (after healing, heat etc) to fat? Otara ---
**Author:** ![MC\_E](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@MC\_E](https://boards.straightdope.com/u/MC_E)\ **Post date:** [August 4, 2008, 1:50am UTC](https://boards.straightdope.com/t/how-fast-do-extra-calories-convert-to-weight-gain/458726/7 "2008-08-04T01:50:58Z")
On a similar note, if you process a meal very quickly through your digestive system, do you get all of the calories/fat/nutrients the food should have contained? I’ve had experiences where something didn’t agree with me and was in my body about 90 minutes tops. (TMI alert - it was still identifiable as what I had just eaten).