One week in and the only thing I have noticed is how tired I am. Has anyone else experienced this?

If you're taking in a decent minimum, it could be temporary.

BUT... big but... your deficit could be too low for your activity level.

TL;DR go ahead and calculate your TDEE off of a sedentary activity level and take a 500 - 1000 cal deficit off of that, but if you're super fatigued all the time, up your calories a couple hundred and see if it increases your energy level while still allowing you to lose weight.

I'm a 5'5" woman, and a LOT of women around my height on here seem to get by just fine on 1200 calories. According to TDEE calculations at a sedentary activity level, that would have been 1000 calorie deficit for me at my starting weight. 1000 calorie deficit is doable altho aggressive and 1200 is largely considered an adequate minimum for women of average height.

I started at 1200 for the first 2 days I was counting and could. not. do. it. I was confined to the couch all day, completely fatigued. I upped my calorie goal to 1500 and was fine. I lost at a great pace at this higher amount. ~2 pounds per week over the past ~3 months. So, by science, this means that, for me, 1500 really is about a 1000 calorie deficit. This means my activity level was bringing my TDEE up closer to 2500, rather than the 2200 predicted by the sedentary activity calculation. I had been increasing my walks, weight lifting at the gym, and doing sports. But also, I'm one of those people who can't sit still all day. I have a sit-in-front-of-the-computer-all-day job, but I am constantly popping up to get a drink or chat with someone in another part of the office. This is the NEAT that is often touted as the reason certain people lose weight at different rates, etc.

Granted, some of this was water weight, but, also, 1500 was my MINIMUM. I calculated the average over this time and my daily average was actually 1700. The undistputeable fact is, tho, that I was able to lose quite a decent amount of weight, 23lb since Jan 5, without going to the extreme minimum for women of average height, which is 1200 calories/day.

It's fine to start at the minimum, but it may be too little for you and your activity level.

/r/loseit Thread Parent