Can you lose weight "too fast"?

73CL350 wrote: »

What's the real risk ? Is it the loss of muscle? Anything else?

I'm down 16 lbs in 32 days and wondering what the potential issues are. Obviously starter water weight is a big chunk.

5' 8" male
SW 186
CW169.2
GW ~149 (acrual goal is 12.5% BF)

Dude, that's a lot. I lost 15 lbs in my 1st 32 days (actually in my first 21 days, and then plateaued for a week and a half, but I started out at 313 lbs and I'm 5'9." I'm also female, so it makes sense you'd lose faster, but still - that's a lot.

To get scare-monger-ey on you for a bit:


Overly rapid weight loss can make your liver deposit extra cholesterol in your gallbladder, where it forms part of what's medically termed "gallbladder sludge." And what may eventually creep forth from the sludge are gallstones - it turns out that most gallstones are made of mostly cholesterol.

The thing about loss of muscle is that your heart is, basically, a muscle. So are a lot of important parts of your other important innards.

It's rare for electrolyte imbalances to get really severe; but when they do get severe, they can lead to kidney failure, liver failure, and/or heart failure. You don't want any of those.

73CL350 wrote: »

I guess I need to say "yes its 17 lbs in 33 days ... but its 10 lbs of water"

So more like 7 lbs in 33 days which is what I could expect if I just kept everything the same. And is reasonable.

We now swap sacre-monger-ey stuff for geeky numbers stuff. The rule of thumb is that you should lose no more than 1% of your body mass per week. For your start weight of 186 lb, that's 1.86 lb/week.

Assuming you lost 10 lbs water weight in your 1st two weeks:

17 - 10 = 7 lbs

32 -14 = 18 days = 0.39 lb/day

7lbs/18 days = 0.39/day = 2.72 lb/week

Or about 1.5 times faster than is considered a safe rate of weight loss. So, depending on just how fast you lost that first 10 pounds, what you're doing now may not be the reasonable way to continue.

And, since you now weigh 169, your current safe-weight loss rate is about 1.7 lb/week. Since 3500 calories excess/deficit = 1 lb gain/loss:

500 calories excess/deficit per day = 1 lb gain/loss per day.

2.72 lb/week current weight loss rate - 1.7 lb/week safe weight loss rate = a very convenient 1 lb/week or 500 added calories/day.


Since this all depends on my assumption about how much water weight you lost how fast, you might want to add just an extra 150-250 calories/day for a few weeks to see how it all plays out.

Early on, people tend to have lots of enthusiasm for their weight loss, but not much data about how the weight loss process works for their individual and idiosyncratic bodies. I'd recommend you take things a bit slower, and pay careful attention to how your body responds.

The number MFP gives you already includes your deficit.