Advice is Really Appreciated: 10 lbs in 5 Days

Hi, Last week, I returned from vacation. I maintained a healthy diet throughout the week, though likely too few calories. Since I returned five days ago, I increased my calorie intake (+500 daily, with much of it an increase in protein powder and fruit) to my normal, pre-vacation level and also completed four half-marathons. In this period of only 5 days, however, I have also gained 10 lbs – all of it in my stomach. My abs (typically six pack) are totally gone, and my stomach is distended and incredibly flabby and jiggly.

What could cause such a rapid increase in weight? Is this belly fat?

I visited my DR yesterday; though he was concerned (“10 lbs in 5 days is not good”), he provide no insights and only requested blood work, which was normal. A second DR requested an ultrasound, which didn’t reveal any problems.

I thought someone on this forum may be able to provide more help. I’m not sure if I should be really concerned.

Thanks for any recommendations on what could have caused this and what I can do to return to normal.


Unless you are exaggerating I would go to an er if you develop more symptoms such as fever, confusion, cough, etc.

You did 3 half-marathons in 4 days and only upped your calories by 500 a day? You may be suffering from an electrolyte imbalance that has caused you to retain water. Get plenty of potassium and things should get back to normal.

Do you normally do 4 half marathons within a week?

The only reasonable answer is water retention.

Thanks for the recommendations. I typically run 30 or so miles per week (rather than 4 half-marathons = 52.4 miles). So yes, I did increase my mileage. I’ll increase my potassium intake ASAP. Thanks again for the quick replies.