"Water weight" - temporary fluctuations during fat loss

How to recognize the patterns and how to think about them

tl;dr:

• Rapid weight loss will often include 3-7 days of initial “water weight” loss (1-2lbs/day for me)

• Going off the diet even briefly will rapidly put that weight back on

• This doesn’t mean the diet “doesn’t work,” it’s just noise to ignore

• Important is the slower, sustained (0.3lb/day for me) loss after the initial swing settles

ZOMG I lost 13lbs in 11 days!

Yea, but it was just water weight, bro.

That’s a common refrain. And it’s not wrong. Many rapid fat-loss diets including low-carb, keto, carnivore, fasting (and many others) will induce an initial weight loss that consists not mainly of body fat and that won’t continue (at that pace) for much longer than a few days or maybe two weeks.

And yes, that weight will come back just as rapidly if you go off the diet even just briefly (e.g. just one meal).

But is that bad?

I don’t think it’s bad at all. It just means you have to set your expectations correctly. Your weight loss won’t continue at a pace of 13lbs per 11 days forever. And if you ever take a break from the diet, cheat, or refeed, you’ll gain back a bunch of pounds instantly.

That’s just something to know and keep in the back of your mind. And it means you should run drastic diet experiments for at least 30 days so you can identify and correct for this initial, super-rapid weight loss.

Let’s take a look at my weight for the last 6 months. Yes, it’s been almost exactly 6 months to the day that I started doing ex150!

Weight loss over almost exactly 6 months. Notice distinct phases of initial super-rapid loss, followed by slower loss, and very rapid short-term regain of weight on refeeds.

The green shaded areas are when I was running (mostly ex150-based) diet experiments. There is a very distinct shape to my weight after I begin a diet.

1. An initial, super rapid (1-2lbs/day) weight loss phase that lasts for around 5 days

2. A sustained, slower (.3lb/day) weight loss phase until the experiment ends

It kind of looks like a hockey stick. The shorter, steeper head is largely temporary “water weight loss.” The longer handle is the sustainable rate of actual fat loss.

So if you’re trying to lose a substantial amount of weight you can just ignore the first few days of any given diet you’re trying. For me it’s typically about 5 days but it might be more or less for you.

One thing to be said: the disappearing water weight definitely makes me look a lot slimmer, less bloated, and my clothes fit looser, especially around the midsection. So it’s not like there is no positive effect to the water weight loss. Just realize it’s not going to continue at that rate.

Example: crazy swing sizes

This blog is about graphs and numbers. Let’s view the above chart a bit differently. Here I’m just highlighting the craziest short-term changes I’ve seen over the last 6 months.

First, notice how tight and smooth the weight usually is on ex150. Very little day-to-day fluctuation. A pound here or there. Maaaaybe two.

Red: short-term weight gain. Blue: short-term weight loss.

And now look at the crazy hairpin turns my weight makes when I go off and back on the diet:

1. After I went off ex150-1 I gained 7lbs in 3 days. Then I lost 8lbs in 4 days going back on ex150-2.

2. During ex150-2 I had a “social cheat meal” consisting of Very Delicious BBQ, including a lot of coleslaw. Up 3lbs the next day from a single meal.

3. After going off ex150-2 I gained 6lbs in 1 day. I might’ve totally stuffed myself that day (still keto foods).

4. The 14 day break between ex150-2 and ex150-3 was an ABA experiment to verify to myself that it was really the diet making me lose weight and I didn’t have cancer or anything. I did gain a ton of weight. Some of it was temporary and some was fat.

5. After the 14 days, before the start of ex150-3, I lost 9lbs in 5 days eating only pemmican. This was most of the weight I had gained during the 14 days off-diet. About 3-4lbs remained and those were probably fat I gained during that time.

6. I went right from eating only pemmican into ex150-3 and my weight didn’t tick up even a single pound in the transition. Both pemmican and ex150 are very low water retention.

7. After going off ex150-3 I gained 10lbs in 3 days. This was the first time off ex150 that I was actually quite unhappy with my off-diet “feasting.” Most of what had been my favorite foods weren’t actually that appetizing any more. Everything made me feel stuffed & bloated. Nothing gave me satiety. It all felt like junk food.

8. Going back on ex150-4 I lost 9lbs in 5 days. On this one I’m not sure if I gained 1-2lbs of fat in the 5 days off or if the water weight just took a little longer to come off.

9. I went right from ex150-4 (after only 20 days or so) into ex150deli. There is not a single pound uptick in weight during the transition. This was actually a great baseline to test ex150deli: had I had 5-10lbs of water weight to lose, I would’ve had to discard the first 5-7 days of ex150deli and it might’ve been quite inconclusive. At the least I would’ve had to run the experiment longer. This bit me later with ex150choctruffle when I didn’t start with an ex150 baseline.

10. Going off ex150deli I gained 5lbs in 1 day. I only stayed off-diet for that single day because I was finally convinced that most of my “cheat foods” had ceased being appetizing and just made me feel bloated and bad. I missed the simplicity and “empty belly satiation” of just eating cream, lol.

11. I went back on ex150choctruffle the next day and lost 3lbs that very day. Unfortunately this initial water loss really confounded the experiment and I ended up not getting a clear conclusion for that experiment.

What can we learn from these spikes?

• +5lbs in a single day is easily possible

• +10lbs in 2-3 days is easily possible

• This temporary weight doesn’t come off quite as fast as it comes on, but it’s close.

• -8lbs in 4 days, 2x -9lbs in 5 days.

My conclusion is that it’s best to just ignore the spikes. Identify them on your graph or however you track your weight. Once you’re back to your baseline weight from before the water gain the rate will slow down to your sustainable fat loss rate and you can start counting that.

For the tape measure people: yes, waist circumference changes just as quickly with these hairpin turns. In fact it changes more. I see 5cm changes in a day, which is equivalent to about 10-15lbs in measurement accuracy.

It would be interesting to run back-to-back DEXA scans before/after a refeed and see if the values change dramatically.

Is it really water weight?

Probably mostly water weight, yes. But there are other factors too.

Muscle glycogen depletion

Glycogen is a form of sugar that is stored in the liver and in our muscles. The muscles use it to refill their energy storage and the liver can dump what it stores into the bloodstream to maintain stable blood glucose should demand for energy rise.

The Wikipedia article says that an average adult human can store up to about 500g, or just over 1lb, of glycogen. Since many of the diets causing these temporary weight swings are very-low-carb or even ketogenic it makes sense that glycogen would get depleted, especially combined with working out.

I don’t currently work out. But I can tell my arms look way thinner when I’m a week or so into ex150. Then when I re-feed they suddenly look way bigger again. It’s a pretty stark difference. That’s probably just muscle glycogen and some intramuscular water retention.

So we can attribute approximately 1-1.5lbs just to glycogen depletion and refill. The rest is probably mostly water retention.

What causes water weight retention?

In short:

• Salt intake

• Carbohydrate intake (via insulin)

• Protein intake (via insulin)

• Fiber (binds water in the colon creating massive 💩)

• Inflammation (I went up by 2lbs for 3 days just from getting a sunburn!)

ex150 is technically not opinionated about salt (I don’t think salt is bad) but I don’t use any. So, in practice, ex150 for me is very low salt, very low carb, very low protein, and very low fiber. That’s why the weight line is so neat and has such little fluctuation. On previous diets I would often see 3-5lbs of “noise” in day-to-day weight fluctuation (and worse in waist circumference).

What about PUFAs?

Some people think that polyunsaturated fatty acids can increase water retention. I am planning to spike myself with some soybean oil while on a baseline-low-variance diet to test this hypothesis. So far I don’t know.

Inflammation, really?

Absolutely. Check out this picture-perfect flat weight loss until I get a sunburn one day - and my weight goes up 2lbs. After 3 days it drops back down to where it was.

Author’s unfortunate inability to tan.

The Whoosh

The Whoosh is a phenomenon in fat loss circles that describes how people will often see an increase in weight briefly only to suddenly drop to lower than they were before (“whooosh!”). They also often report that their body fat (e.g. on the belly or legs) feels different during that time, as if it’s kind of grainy or there’s little bumps in there.

The idea is that maybe the fat cells are emptying out and somehow, instead, water is retained. Then at some point the water is released from the body and total weight drops.

I will say that I definitely do experience such “plateaus” and then sudden drops. But I don’t know if they’re cause by water retention, the inherent inaccuracy of the scale/measuring tape, something else, or a combination of it all.

It definitely feels like a “whoosh” sometimes.

Do these temporary fluctuations stop actual fat loss or do they just mask it?

The money question. Why is this important?

If fat loss continues unabated and we’re just not seeing it because of the temporary increase in muscle glycogen and water retention then we can take short breaks from the diet all the time and not worry about it. We’re not going to gain any fat in 1-2 days off diet, be it for social reasons, going to a wedding, to refeed on protein, enjoying our favorite foods, whatever. We’ll just take a few days to get rid of the temporary swing and then continue right where we left off.

If, on the other hand, this actually does stop fat loss then taking breaks will halt our progress. Should we do it enough the diet becomes useless. (This isn’t just true for ex150, by the way, but for any diet.)

I am not sure which one is true or if it’s something in the middle. It’s definitely demotivating to see the scale jump back up 5 or 10lbs. The pants definitely become tighter again because water has mass. I’m not a bodybuilder but I think muscles look bigger when they’re full of glycogen vs. completely depleted. So your shirts could be tighter too, lol.

One cool experiment to test this:

Do a very brief, weekly refeed on non-junky food that causes both glycogen to replenish and water retention through insulin. If you’re keeping it keto I would suggest just eating a whole bunch of lean meat. If you’re not doing keto.. well, pick some healthy carbs or something.

If you do this long enough (e.g. 30 days) with roughly the frequency that it takes you to gain/lose all that temporary weight you should either see the trend line plateau or keep going down.

E.g. it takes 2 days to gain 10lbs and 5 days to lose 9lbs in some of my examples above. That neatly adds up to a week. So I could do ex150 for a month but eat a ton of ribeye steaks (or other lean meats (yes, ribeye is a lean meat)) every Sunday. I will definitely see a huge weight spike due to muscle glycogen and water retention through insulin. But over the course of a month or more I should be able to determine if my fat loss continues through that water weight roller coaster or if I’m the same weight at the end of the experiment.

If only we had someone who did a ton of really weird experiments.