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Rapid Weight Changes in the Same Week

I’ve been experiencing rapid weight loss and rapid weight gains in the same week.

I’ve been working out for almost year every weekday.

I’ve done my homework and know that I’m a mesomorph and I have my macros dialed in. I use MyFitnessPal to record my food and I wear a Fitbit charge2 everyday and record each workout with it. I have a water coach app that helps me drink 85+ ounces every day.

I change my workout every 4 to 6 weeks and I’m trying to reduce my body fat. I’m very serious about losing the fat and I don’t have cheat meals or cheat foods but have weighted the same for over 2 months​.

I first experienced this issue 2 weeks ago when I injured my levator scapula (had to see the chiropractor to fix it), so I was told to take a week off. I followed my meal plan and kept​ my macros and calories in check and didn’t do any lifting for 1 week. I did my weekly weigh-in and found in 4 days I loss 3 lbs. I was excited.

However, after only 1 day of working out (yes, I weighted myself everyday during this time because of the rapid weight loss) I found myself weighing the same prior to my injury.

Is it possible to lose and then regain 4+ pounds after only 1 day of working out?


It is not possible to lose 4 pounds of fat and regain it in a day. But it is possible for your weight to fluctuate that much through changing levels of water and glycogen retention.

This is normal.


Yup. The rule of thumb I’ve heard is that fluctuations of up to 2% of bodyweight are considered to be within normal limits (ie, attributable to changes in water, glycogen, waste, etc).

Thank you for the replies.

I find this change frustrating and fascinating. I was worried I might be missing something or that there was a physical issue rearing it’s head.

This is why I weigh myself every day–so I can see and get a sense for these fluctuations.

I like to weigh myself the night before I go on a 36 hour fast…fun to see you ‘lose’ 5 lbs in 1 day…then again…you gain it all back…maybe that’s why I switched to weighing myself once a month…as long as my pants fit I don’t worry how much I weigh day-to-day.