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Gained ten pounds in a week--it's not real, it's not real, it's not real

29 replies22 peopleMar 6, 2026☆ Follow
Summary

why does weight jump 7-10 pounds after starting gym exercise plus more carbs and salt

The thread shows the gain is temporary water from glycogen storage, sodium intake, and exercise-induced inflammation rather than fat or muscle. Multiple people report similar overnight jumps after carb loads or restaurant meals that reverse within days once habits return to normal. Nighttime weighing and low-carb history amplify the effect because glycogen binds several grams of water per gram stored.

What this discussion establishesWhere people disagree

whether muscle literally weighs more than fat or simply packs denser for the same weight

Still open

how many days the water typically takes to subside once salt and carbs drop again

Nothing here is advice.

29 replies · 22 people
SteadyQuill55archiveopening postMar 6

My target is 125 and I was sitting at 131. Signed up at the gym because it was time to move activity from very light to moderate so I could get strength and stamina back. Rode the bike there and back daily for nine miles round trip plus swam about forty minutes, and allowed a bit more food and protein so I would not feel wiped out. Scale hit 141 last night. I know the math on calories does not add up to real fat, but I ignored salt and had several salty meals. This has to be water and I am trying not to spiral while I go back to the prior deficit and keep the swimming and biking. Clutching the cat and repeating it is just water. Bodies are mean for hanging on to ten pounds like that.

QuietAlder25archiveMar 6

You are probably adding muscle too. It weighs more than fat. When I ramped up workouts I saw the scale rise yet lost an inch at the waist. That kind of change is positive.

SlowAlder76archiveMar 6

I get it. I put on 22 lb in two weeks a month back just from eating a little above usual. Dropped ten of those pounds fast and can usually shed two or three pounds a day once I return to my normal deficit. The whole situation feels absurd.

LevelTimber64archiveMar 6

Still discouraging even when I remind myself it is not actual gain. Impressed you ride the bike to the gym though.

IronCinder88archiveMar 6
↳ replying to @SteadyQuill55 (opening post)

That added weight is muscle. Do not worry about it because it is beneficial long term. Extra muscle will help burn more fat later. Have you tried a scale that also reads body composition? It can ease the focus on the plain number.

NorthLantern99archiveMar 6
↳ replying to @QuietAlder25

Strictly speaking that is not accurate. A kilogram of muscle and a kilogram of fat weigh the same. Muscle is simply denser so the same weight takes up less space.

SlowBramble78archiveMar 6
↳ replying to @NorthLantern99

Technically correct. It is like saying a pound of feathers weighs the same as a pound of gold.

QuietAlder25archiveMar 6
↳ replying to @NorthLantern99

I meant it takes up less room. One cubic centimeter of fat weighs less than the same volume of muscle. I should have been clearer. The smaller volume and higher metabolism are still good.

LevelFenwick52archiveMar 6
↳ replying to @NorthLantern99

Hard to tell if this is meant to stir things up. Same idea as claiming a pound of feathers equals a pound of steel.

QuietAlder25archiveMar 6
↳ replying to @LevelFenwick52

That brings back a trick question from a college physics test.

PatientAlder89archiveMar 6
↳ replying to @SteadyQuill55 (opening post)

Could be PMS or lots of other reasons for the jump. Do not let it wreck your weekend. Body composition is probably shifting in a helpful way toward your goal.

SteadyQuill55archiveMar 6
↳ replying to @LevelTimber64

I vented then went to work. Thanks everyone for the support. Doubt it is muscle already. More likely the pad thai, salami, cheese, rice dish and similar salty restaurant meals after months of low-carb home cooking. That combination turns me into a water balloon. I do not drive so I walk, rideshare or scooter, but four and a half miles is too far for those options and the bike works well. Feeling oddly young again at 45 and have not ridden a bicycle in twenty years.

SteadyTimber49archiveMar 6

Scales can really mess with your head. Not real gain but still frustrating.

KeenTimber66archiveMar 6

After a big sushi carb day I woke up seven pounds heavier. It is glycogen plus the water it pulls in. Leg day burns it off and the scale drops again. Over the week I still trend down in a deficit. Learned this pattern after two years on keto then adding carb cycling around workouts.

GreyCompass75archiveMar 6

The actual density difference between fat and muscle is only about fifteen percent. Water adds far more weight.

BlueAlder28archiveMar 6

Episodes like this make me consider a body-composition scale. Regular scales give useful but sometimes misleading numbers. Good ones cost a lot though.

KeenTimber66archiveMar 6
↳ replying to @BlueAlder28

I use a budget smart scale. Weigh daily, screenshot, and let AI summarize trends. After a carb-load day the jump is expected from glycogen and water. The scale shows higher body-fat percent but that is just the water. Schedule has lower-body work the next day so the stores get used. True fat loss keeps happening underneath.

LevelTimber64archiveMar 6
↳ replying to @SteadyQuill55

Nice. Glad the bike is bringing back that good youthful feeling. You are doing great.

CopperSignal27archiveMar 7

After low-carb eating glycogen stores are low. Adding carbs refills them in the liver and each gram pulls several grams of water. A fast ten-pound change without huge calorie intake has to be water. You cannot add that much muscle in a week or two and fat would require far more calories. It is basically the reverse of what happens when a diet starts.

SteadyPebble62archiveMar 7

Sounds like body recomposition. I am trying to focus less on total weight and more on measurements and whether muscle is trending up. Gym four or five days a week and hitting protein goals but the medication makes eating difficult.

ClearLantern81archiveMar 7
↳ replying to @SteadyQuill55 (opening post)

This happens often when activity jumps suddenly after weight loss. New exercise causes tiny muscle tears and fluid moves in to repair them. At the same time glycogen stores refill and each gram holds three to four grams of water. Saltier meals add more retention. Weighing at night also shows several extra pounds from the day's food and fluids.

PatientAlder37archiveMar 7

No need to panic. I have stayed at the same weight on the new medication yet can see visible change and needed a smaller belt. The body is still reshaping even without scale movement. After big initial loss it makes sense that priorities shift from storage to using energy.

CopperFenwick68archiveMar 7

Started lifting again the same weekend I ate Chinese food three days straight. Both caused water retention that showed as eight pounds on the scale.

BrightWillow80archiveMar 7
↳ replying to @KeenTimber66

I have the same brand of smart scale but have not set it up yet. Planning to because the extra data looks useful.

ClearBramble68archiveMar 7

Salty meals really do cause surprising temporary gains. Same idea as the opposite of starting a diet where twenty pounds can drop in a week that is not all fat.

SteadyQuill55archiveMar 7
↳ replying to @CopperSignal27

I expected some increase once I started including rice, noodles, bread and potatoes, especially from restaurant versions high in salt. Portions were not huge yet still enough to matter. Thought it might be four or five pounds, not ten. Added the food so the longer bike and swim sessions would feel doable and also tried more salt to help with lightheadedness on standing. The lightheadedness improved but the scale surprised me anyway.

ClearWillow59archiveMar 7
↳ replying to @SteadyQuill55 (opening post)

I only weigh first thing in the morning after using the bathroom with no clothes on for the lowest reading. Salt alone can add two to five pounds right away.

KeenBramble97archiveMar 8
↳ replying to @ClearWillow59

Once bought a whole prosciutto leg and worked through it over months. Gained six pounds the week I started it and lost those six the week after I finished.

CopperSignal27archiveMar 8

Had eight straight weeks of losses then saw a half-kilo increase. Real weekly change is only one or two hundred grams so random swings are larger than actual progress. A five-kilo jump would feel awful.

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