Losing Weight and Fast


I am on a 30 day Nothing-but-soylent diet (I don’t want to say diet but I couldn’t think of any other words). I built up to it per instructions from Rosa Labs so I have had hardly any side effects other than a mild headache and some mild dehydration at points. However today (day 4) I weighed myself and I have lost 15 pounds in about a week and a half after starting Soylent. I don’t know if this is healthy to be losing weight this fast. I am not in the slightest bit upset, after all this is one of the reasons I bought it. However I am just concerned if this is healthy or not. To give some insight into my situation before Soylent I weighed 276 and I currently weigh 261. So I definitely have extra weight to lose but I’m just worried.


My first guess would be that you have lost a lot of water due to the lower carbohydrate intake of the Soylent diet.
Most people eat way to much carbs and carbs retain water.


I wouldn’t be too concerned at this point. Even if you’re adding the salt as instructed you are probably getting a fair bit less with Soylent than you were before, in which case the majority of that weight is likely water. If you continue to lose 10lbs/week and want to slow it down you can increase your caloric intake.


I was 6’5 280 when I was on a diet several years ago. And I was on a my own kind of diet that was approved by my cardiologist and I was losing a minimum of 2 pounds and as much as 4 pounds a day. I only followed the diet 5 days a week. I was drinking tons of liquids especially tea. But tea is a mild diuretic. And my doc said dont worry about it. I was way overweight and its not uncommon to lose a lot of weight initially.


So if it is water weight does this mean I need to be drinking more water or that I am losing more water than I am taking in? Is that a bad thing?


One possibility is if your diet was high sodium before you started soylent, then you might simple have been retaining water. In other words, the weight you’re at now might be closer to what weight you would have been at anyway if not for the sodium. (Aside from the couple-few pounds you might have actually lost since starting.)


The easiest way to tell if you need more water is the color of your urine. If its clear or a really pale yellow you have plenty of water. Its when it starts to get to the darker yellows that you may be considered dehydrated. That being said, if you are losing more water than your taking in and its a clearer yellow then no, its not necessarily a bad thing.

If you lose weight fast and feel fine, I wouldn’t be too worried. If however you don’t feel well, you may be losing weight to fast. Your body does talk to you, if you listen. Its just a matter of learning how to understand what its telling you, and no two people are the same.


I would say make sure you are well hydrated for sure. As long as you arent a heart patient drink as much water as you feel comfortable with. And like Matt8 says as long as you feel good and have energy you should be okay. (go to your doctor)


Same thing happened to me the first week and half. I lost around 15+lbs then it kind of leveled off. I have been hovering between 15-20lbs down since starting official Soylent 7 weeks ago.


I am dying of jealousy. No weight loss for me because I like that stuff too much. I don’t like the taste of the low-kcal recipes and Soylent, schmoylent and marion chow have too many kcals to allow weightloss. Using only 75% of the recipe per day would only work if someone locked me in a cage around 4 pm.


When people refer to losing “water weight,” what they’re generally referring to is glycogen depletion. Our bodies store carbohydrates in lean muscle tissue, in organs (mostly the liver) and a little bit in some other bodily tissues in the form of glycogen; this is returned into the bloodstream when sugars are depleted, either because of exercise demand, or because of several days of reduced carbohydrate intake.

When people “carb load” before a marathon, they’re trying to increase this glycogen storage.

What does this have to do with water weight? Glycogen can’t be stored by itself; each gram of glycogen is stored with three to four grams of water. When you release the stored sugars, you also release the stored water.

So if your body had a pound of stored carbohydrates, and you’ve been on a reduced-calorie diet for several days, and you use up one pound of stored glycogen, you’ll also release and lose close to four pounds of stored water, for five pounds of total weight loss. This is not water you need to replace, nor is this loss of water an effect of dehydration. This also has nothing to do with whether or not you lost any fat - you might have also lost fat, you might not.

It’s also useful to note that when you end a diet, and begin eating normally, your body will replace the glycogen stores. So if your body stores away a pound of glycogen in your muscles and liver, those tissues will also be plumped with an extra four pounds of water… which means that as you “come off the diet,” you may gain five pounds of weight… but none of this weight is re-gained fat. It’s normal volume of lean body tissue.

So when you regain a couple of pounds in a few days after coming off a diet, don’t panic. You may just be carb-loaded. Go exercise; you’ve got the energy. :smile:


Yeah, what he said. Drastic weight loss at the start of a diet is typically “water weight” which includes those glycogen stores.

Losing fifteen pounds is also a meaningless metric. What is that as a ratio of your total body weight? For you, that is slightly more than 5%. Not a huge amount if you have a higher than average amount of body weight. I suspect you do, based on the fact you are using Soylent to lose weight.

Now if we had a 150 lb marathon runner with 4% body fat lose 15 pounds, that would be a 10% loss in weight for someone who is already very lean and who likely does not have much in the way of glycogen stores (he uses energy as fast as he consumes it). That would be a reason to seek medical attention.

If you continue to shed that much weight on a Soylent-only diet after 10-14 days, that might be an issue. I would keep track of other symptoms such as lethargy and headaches (be sure you add 1/4 tsp non-iodized table salt to a day’s batch). But keep in mind that as your glycogen stores deplete and your body is forced to switch to fat-burning mode, you will likely feel very tired for a couple days until your body adjusts.


Just wanted to second @Snowman’s comment about taking your total body weight into account. If you’re mostly muscle or extremely tall, the weight loss might be more worrying than if your body composition is not as lean.

Similarly if you’re, say, 6 ft and 250 lbs, then your weight loss will probably slow relatively soon because your ‘healthy weight’ will probably be around the 180-200 mark (that might be low, I’m not sure…I’m a girl so I’m not familiar with normal weights for tall dudes). On the other hand, if you’re 5 ft 2 in and you weight 250, you can expect to have rapid weight loss like this with a controlled, healthy diet/caloric intake, and you will continue to see rapid weight loss until you get to probably 130-140, which is closer to the ‘healthy’ weight for your body. Then your weight loss should slow to 1-2 lbs per week.


I am about 5’ 11" and I have never had my body fat percentage calculated by a doctor but I am fairly athletic. I ran cross country for the past three years and ever since I’ve been out of school I’ve been continuing running including running in local 5K’s. That’s not to say I don’t have a high body fat percentage. But according to calculators online I am probably somewhere between 25 and 30 percent body fat and I’d like to get down to around 12 or 15.


It sounds great to me. Like others have posted this will be mostly water weight. I typically lose 10 pounds in the first few days of starting an atkins type diet. Soylent isn’t low carb, but the low sodium may be doing the same thing.

Can you estimate how many calories a day you used to eat?
Take that number and subtract the 2000 you get from Soylent. Every 3500 is about a pound. So once things level out in a couple weeks you probably won’t lose more than 1/2 pound a day unless you are very active.

I think the main thing is that water comes and goes just don’t get to dehydrated, and after that you want to be losing fat and not muscle. If you finances allow for it, consider getting a DEXA scan done asap. This will give you your exact pounds of fat in each region of your body. Then redo the test every ten or twenty pounds of weight loss to make sure what you are losing is mostly fat.

This way you have some hard numbers as to what exactly is being lost, if significant muscle is being lost as well then you need to slow down the weight loss.
These scans aren’t cheap, as much as 150$ each, although I know in Austin the university will do them for 1/2 that so maybe other schools have similar deals.
This cost will be a deal breaker for many, but to others it might be a non-issue. If you are in the later category I recommend them.


I’ve personally settled after that first 10ish pounds of bloat/water/bowels, and am losing between 2-4 pounds a week (which is the edge of what’s considered safe).

I’m 6’1", broad frame, started at 290. Goal weight is 210, currently down to 276. According to most calculators, my basal rate is about 1900 calories. I’m drinking between 1250 and 1500 depending on activity levels (I actually had just 1000 on a couple of exceptionally lazy weekend days).


One way to try and make sure you’re losing fat and not muscle is to do at least 15 mins of moderate strength exercises at least every third day. Even just a round of 15 squats, push-ups and tri-ups. If you have even 5 or 10 pound weights, throw in 15 curls. You won’t bulk up, but it’ll encourage your body not to eat what you’ve got.

I don’t think it’s possible to lose bone density at the rate described without some kind of hyper-osteoporosis.

(edit: I used to be in really good shape until I wasn’t)


Those tests sound great for the data but I definitely cannot afford them. Also, as crazy as it sounds, part of me wants to lose some muscle mass. As I mentioned before I am what most consider to be an athlete. I run all the time despite the extra weight I carry so I’ve built up muscle to carry all that weight. And perhaps it’s stupid but I don’t want massive muscles from my old body I want mucles that are proportional to the size I will be.


I am just under 6’ and started around 250 with an average frame. I used to be in the military and know what their ideal weight is, combined with the BMI charts and real world experience… I should be between 190 and 200. With my build I could get down to 175 and be healthy but it would be a ton of work to maintain. Not realistic.

Just my twenty cents being a man around the size you mentioned.


You can do a poor man’s body fat measurement with your neck and waist. It is actually fairly accurate as long as you are not obese. Calipers are 90% accurate, a water test is 100% accurate (both cost money and tell you what you already know). But take a measuring tape (literally tape, the kind tailors use) and you can plug the numbers into a web site for free.

Calculator 1
Calculator 2

Or just Google it