Why does my weight change after eating?

[ConcealedDreamer]

Over these past few weeks, I've be wanting to watch my diet carefully, so I scale myself every day. I noticed that before dinner, I was 140, but after dinner, I was 143.5. Why is that? I am sure I didn't instake 3 pounds of food...

 

[Moonbear]

Two things come to mind. First, how much water are you drinking with your meal? Maybe you're not eating much food, but are consuming a lot of water? Second, how accurate is your scale? I know my bathroom scale isn't that good, and I can step off it and step right back on and it will be 2 lbs different. It's close enough for my needs, but won't be useful if you're trying to track every pound. If you have a slightly uneven floor, that will also affect the accuracy of your scale. So, it may have nothing to do with your actual weight or what you consume, but just that the scale has some variation in accuracy.

 

[honestrosewater]

Ah, am I crazy or have you -Moonbear- made almost the same exact post before?

Oh, and 3 pounds of food doesn't sound like an unreasonable amount, though maybe in one sitting? Okay, I can't vouch for the sources, but they were quick:

The average American consumes 2-3 pounds of food per day.
- http://www.drlam.com/faq/Diet.cfm

According to the USDA itself, in 1994 the average American ate the following:

* 586 pounds of milk and dairy products
* 394 pounds of vegetables
* 199 pounds of meat, and
* 193 pounds of products containing flour and cereal
* 121 pounds of fresh fruit.

That totals over four pounds of food per day per person -- and nearly forty percent of that is milk and dairy -- which makes one very lopsided food pyramid!
- http://www.vegsource.com/articles/milk_pyramid.htm

I'll check the USDA in a minute. And for more detail.
I can't find pounds per person per day data all compiled in one list, but you can find the data at http://www.ers.usda.gov/data/FoodConsumption/FoodAvailSpreadsheets.htm
and do the calculations yourself, if anyone really cares that much.

 

[ConcealedDreamer]

I'm pretty sure my scale is right, I go on it everytime and I get the same reading.

 

[Moonbear]

Ah, am I crazy or have you -Moonbear- made almost the same exact post before?

Can't it be both? I might've if a similar question was asked before.

Oh, and 3 pounds of food doesn't sound like an unreasonable amount, though maybe in one sitting?

Well, since he said he was watching his diet, I was assuming that meant he was paying attention to how much he was eating during that meal. 3 lbs of food would be pretty hefty for a single meal (not that I haven't seen people pack that much down), but if you count in drinking a lot of water, it doesn't seem so unreasonable.

Of course, I'm also making the assumption that before and after dinner means you weigh yourself twice in the same day, just before dinner and just after dinner, not some days before dinner and some days after dinner or first thing in the morning vs after dinner.

 

[honestrosewater]

Can't it be both? I might've if a similar question was asked before.

Yeah, I already found it: https://www.physicsforums.com/showpost.php?p=526840&postcount=15
I'm not crazy! My scale also varied a bit as I moved it around, BTW.