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Obesity and Weight Management

Water gain



From doing some extensive reading, I understand that after being on a low-carb diet and reintroducing carbs, the body begins to gain water weight as carbohydrates rehydrate the body.

My question is this -- is there a "limit" or cap to this water gain? Is there a point where it stops and you finally begin to see the scale go back down as you lose fat? So far, it seems my numbers keep going up and up and away!

I had gastric bypass in February 08 and after sitting at the same weight for six months, discovered that I wasn`t losing weight because I wasn`t eating enough (go figure). So I started eating 1700-1800 a day and started losing weight. But any time I eat ANYTHING refined, I gain 2 pounds over night. I know this isn`t fat, because I`m not eating enough for it to be fat.

So if I gain water from the refined carb BUT AM STILL EATING WITHIN MY CALORIC BOUNDARIES OTHERWISE, is it possible to still be losing fat even while you`ve gained water? Or when you gain water, must you lose the water first before you start losing fat?

I`ve become so discouraged. It seems to be much harder to lose weight since having the surgery than it was before (again, go figure). It takes SO long to lose weight, so when you gain 2 pounds overnight, you wonder -- is it REALLY a setback? In other words, must I lose the water before I can start losing fat again?

From what I can tell, if I`m losing weight at 1700/1800 calories, then maintenance for me is about 2300. If that`s the case, then it would take me 3300 calories a day to gain two pounds in a week`s time. Impossible now since I`ve had surgery. I just want to know if there is hope with the water weight issue.


There is a often a natural phenomenon after gastric bypass surgery where one transitions from a faster weight loss where often the weight seems to slide right off to a time period where further weight loss is very dependent on your working hard with your diet and exercise. Making the diet and exercise changes are very important to increase the likelihood of long-term success after weight loss surgery.

Also, reasonable expectations after gastric bypass show a typical loss of 60-70% of your excess body weight after about 2 years. Your surgeon's office can calculate this goal for you. However, weight loss after any type of weight loss surgery is very dependent on the individual and factors such as their age, type of surgery performed, metabolism level, sex, weight before surgery, and adherence to the diet and exercise regimen. Some people lose to their goal or more, some do not.

If your physicians feel you can tolerate it, you may wish to add weight lifting to your exercise program. The muscles you build may help burn calories even when you are not actively using them.

I also encourage you to contact your surgeon's office about a weight loss surgery support group or look for one in your community. It will be comforting to talk with other patients.

Good luck to you!

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Response by:

Lisa  Martin Hawver, MD Lisa Martin Hawver, MD
Formerly Clinical Assistant Professor of Surgery
No longer associated