Over the last 3-4 weeks, I've lost 3.2kgs (about 7 lbs, if the online conversion is correct lol). Yesterday, I had a bit of a bad day, found out that my IVF treatment wasn't successful, and I ate half a block of chocolate and half a packet of corn chips (as well as a healthy breakfast and dinner).

When I weighed myself this morning, I'd gained 4.2kgs!!!!! That's over 9 lbs, in one day!!!!!

I don't understand how it happened. Sure - I didn't eat well. But the combined weight of all my food wouldn't have even weighed that much. How is it possible to put on 9lbs in one day? I'm so disappointed. I've blown my whole month's worth of weight loss

It isn't possible. Your bad day yesterday certainly made the scale go up as you are probably retaining water from the chips and you probably ate a bit too much. Get right back on plan and that weight will undoubtedly drop back off in the next couple of days. Sorry about your IVF. Don't worry too much about this weight, just weigh again in a couple days and you will be back near normal...it is absolutely physically impossible to gain 9 lbs. overnight so rest assured, you didn't.

Corn chips are LOADED in salt...so much that it makes perfect sense that 9 lbs of water could have stuck around. Drink lots of water today...I bet you'll see a drop in the scales tomorrow.

There is no way you can gain 9 lbs of fat in a day. You'd have to eat over 31,000 calories above and beyond your normal calorie expenditure. I don't think it is physically possible, and some chips and chocolate is NOT going to do it.

Deep breaths, lots of water. All but a few ounces, at most, will disappear once you clear out the water weight.

As the other have said, scales are , that's why. They have a sick sense of humor that messes with our heads. One day you will eat off plan and LOSE weight one day and wonder how it happened... but it's just the scale, messing with you again.

Think long term, and don't sweat the small stuff!