Weight loss by the numbers


To lose fat, calorie deficit is the fastest and most reliable method. Your return on investment for tweaking macro ratios is going to be minimal at best.

Weight loss and losing fat are conceptually simple, but not easy. It takes time and work. The numbers are general, not specific, but they provide a roadmap. Metabolisms differ. Muggle food and snacking will have an impact on the amount of time it takes to reach a certain goal.

The key is managing your body fat percentage. As a general rule of thumb (it’s not a strictly linear relationship between caloric output and pounds lost) it takes a 3900 calorie deficit per pound of weight lost. If you’re getting sufficient protein per day, your muscle mass will maintain itself. Carbs and fats are intertwined in our metabolisms. Excess carbs get converted and stored as fat. Excess fat also gets stored, and also gets excreted.

Generally speaking, carbs are used for on-demand energy. Proteins get broken down into essential amino acids. Fats are used to shore up deficits. What this means is that after you burn up your on-demand energy, your body kicks in and starts converting those stored fat molecules into glucose for more on-demand fuel.

Step 1: Calculate your BMR: http://www.bmi-calculator.net/bmr-calculator/

Step 2: Calculate your body fat percentage: http://www.bmi-calculator.net/body-fat-calculator/

Step 3: Pick your body fat percentage target from the above chart.

Step 4: Calculate how many pounds of fat you have. If you’re 180 pounds and have 35% body fat, that’s 63 pounds of fat.

Now you have your numbers, you can create your goal. 0% body fat (and dead) would be 117 pounds. Lets say you want to have 15% body fat. This means your target weight will be around 138 pounds. From there, you know that you need to lose 48 pounds (180-132.)

Your body has to incur a caloric deficit in order to burn off the weight. It also has to obtain enough protein to maintain muscle mass. Ketogenic diets kickstart the metabolism to more efficiently burn fats. Low carb high protein diets do the same. The amount of effort you put in, however, remains about the same. There are roughly 9 calories per gram of fat.

Using that general rule of thumb, we can say that with 48 lbs to lose, we need a 187,200 calorie deficit to achieve our weight loss goal.

I have a BMR of 2300 calories per day, roughly. 2000 calorie Soylent meals daily gives me a 300 calorie deficit. By eating just Soylent, if my BMR stays the same, then in 20 months I’ll reach my target of 132 pounds. The tricky part is that you have to increase your level of activity to maintain the same BMR. As you lose weight, you’re burning fewer calories (by carrying fewer pounds) and becoming more efficient.

20 months seems like a long time. Consider that in this scenario, simply by walking 5 miles a day, you’re increasing the caloric deficit by 300-400 calories, without a large amount of exertion or stress. This changes the time to reach your target from 20 months to 8-10 months.

Now if you go all in and ramp up to a strenuous exercise program, you can increase your muscle mass at the same time that you’re losing fat. This means that you can have a higher mount of fat relative to your total bodyweight to achieve the same percentage. To keep it simple, lets say you want to gain 10 pounds of muscle. This puts your 0% fat weight at 127 pounds. For 15% bodyfat, your target weight is 150. You’ll be consuming more protein to build muscle mass while at the same time increasing your caloric deficit to burn fat. If you ran 5 miles and did 45 minutes of free-weight lifting and stretching, your caloric deficit increases to 1000. Since you’re wanting to increase muscle mass, you’re going to increase the amount of protein you’re taking in. 300 calories of protein would be a decent middle ground (assuming you’re operating on the US RDA.)

In this mildly strenuous scenario, you’re operating on a daily 700 calorie deficit, trying to achieve 150 pounds. This gets you to your target in 6 months.

Soylent + a carefully chosen protein source = weight management dream.

If you worked out in a relaxed way, you an burn 300 calories in a day with ease. If you work out really hard, you’re looking at 700+ calories. On the flip side, consuming less calories per day is easier. Since the example above expects 2300 calories per day, with 2000 calories of Soylent, the example gets a 300 per day starter bonus deficit. Moderate exercise is psychologically easier, and results in a 600 calorie deficit, compared to a 1000 calorie deficit for strenuous workout.

If you ease into it and manage your weight, you can be fit and cut like a movie star in 8 months or less, just by walking 5 miles a day and watching what you eat. If you work out like crazy and watch what you eat, you could get there in 4-5 months. Anything sooner I would be afraid of health consequences (this would be for an almost obese male at 180 pounds.) If you’re 10 pounds overweight, you could have a Brad Pitt physique in less than 60 days.

I was actually shocked to find out that women actually have it easier. They can have a higher body fat percentage and achieve a better physique with fewer calories burned.


Unfortunately, I can’t put too much stock in BMR calculators. According to them, I should be eating 3000 or more kCal a day (3 megaCal?).
My soylent recipe is half that. While I’ve experienced some weight loss, there’s no way that my body needs that much. I’m just more efficient at burning calories, I guess.


Well written. Good math, good explanations. Don’t forget though that working out itself alleviates physiological and psychological stress (assuming a well rounded program), as exercise also releases endorphins that can counter various conditions in most folks. Also, every body is different, so mileage will vary from person to person despite the calculations, so some personal experimentation and adjustment is always necessary. And lastly, once body fat reaches a certain point and muscle mass increases, there may actually be an increase in weight for some people.


Do keep in mind that those numbers change dramatically as you lose weight, because unless you’re also doing hardcore strength training, you’re going to lose muscle too.

I’m short, stocky, and have a butt ton of muscle for a girl. I have a BMI of 37 (class 2 obese) but that calculator puts me at 23% body fat. According to those numbers, for me to be at 0% body fat (and therefor dead) I’d weight 148lbs. I have been as low as 125lb in recent years, and did not die (though I did feel grotesquely skinny. It was however the only time in my adult life I was what BMI considers a “healthy” weight! Ugh, BMI…)

So yeah. Just remember to re-calculate your body fat percentage every 5lbs or so, and this should be a pretty useful guide.


It’s all pretty general - individuals have unique metabolisms, so some people are going to have significantly different BMRs. It’s worth a visit to a real nutritionist, or a week of research, to get your numbers done. Once you know where you are, you can map out how to get where you want to be.

Or… you can start walking 5 miles a day, and limit yourself to 2000 calories. For most people, that’d be enough to lose weight and get yourself to a healthy state within 2 years.


I’ve never really understood why people analyse this in such detail, or find weight loss so hard. Just eat a bit less of the unhealthy stuff and do some exercise. Easy.


Muscle mass + activity level = bmr
nothing to do with height or weight or age


Yeah I’m confused by that BMR calulcator, it says I should eat 1300 calories per day. I eat closer to 2000, and any less than that I start dropping weight fast. As I weigh 105lbs, that is not desirable to me.

The body fat calculator says I have 25% body fat (which it classifies as "acceptable), yet my BMI is 19 (which is one number up from being considered underweight). I don’t really put much stock into these calculators; it seems like there’s too many other variables they don’t account for. It seems like if you’re female and you have any amount of muscle, the numbers get whacked? I understand the basics of what you’re saying - eat fewer calories and lose weight. I just don’t think the calculators are really useful.


That sounds like a statement made by someone who’s never had weight issues.

For some of us, myself included, I was only able to lose weight pre-soylent by exercising every morning for an hour. And I lost the ability to do that once my wife started architecture school. Too hard to go to sleep at 1 and get up at 4:30 for a 20 hour day.

If you’ve never had a problem or don’t understand, then congratulations. Don’t belittle those of us who do.


@jrowe47 – Do you have a source for this assertion? Everything I’ve read in this regard would suggest that it is functionally impossible to add muscle mass under a caloric deficit – i.e., your system is either going to be in a catabolic state or in an anabolic one, but not both. The best you can do with exercise in the context of a calorie-restricted diet is minimize the loss of muscle tissue.

This is why adherents to body recomposition programs tend to put themselves through cyclical “cut” and “bulk” phases in order to reach their target.

By the way, for anybody considering the ketogenic approach to the above, I highly recommend the following calculator – it covers everything from the BMR calculation to macronutrient targets, and maps out projected weight loss given the supplied data:


Thanks QuidNYC, that calculator seems to take into account more info. It says I need to eat 2000cal for weight maintenance and have 18% body fat, much more accurate!


This article was written by someone who has never studied biochemistry. Calorie counting is and has always been virtually useless, because one calorie does not equal another. If you don’t change the type of food you eat, you won’t be able to eat fewer calories for any length of time. If you decrease your carb intake and eat more fat, you will effortlessly eat fewer calories and lose weight.

Gary Taubes wrote an excellent and extremely well-sourced book called “Why We Get Fat” that covers this in detail.


I’m not sure if that argument is a valid one in this situation? 'Cause like… the entire point of Soylent is that you’re changing the type of food you eat.


I’m frankly concerned with how many carbs the current official soylent recipe has, along with its glycemic index. Those two factors are crucial to weight loss, particularly for people who gain weight easily. Too many carbs spikes your insulin levels, causing your body to store calories as fat. I’m uncomfortable recommending more than about 100g of carbohydrate in a given day.


Personally, without carbs I get cranky and become prone to fainting. I would not be able to hold down my job on 100 carbs a day, because I would be constantly passing out. Not to mention that it makes it impossible to keep to my diet, because suddenly and inexplicably I feel like I NEED BAGELS TO LIVE. I’ve been having phenomenal success with a DIY recipe that restricts calories and nothing else. So it’s different for everyone.

Sorry to be argumentative, I just get really tired of constantly seeing the carb thing come up. At this point everybody on here knows the argument and is familiar with the research, and seeing it over and over again in every thread is starting to feel like constantly being preached to about a religion I don’t agree with


I can relate; I feel the same way about meat. If I don’t have any in a meal, soon I feel like I’m starving to death and nothing in the world besides meat is food.


And yet, caloric reduction empirically works. It’s not an article, it’s a forum post to start a discussion, and I specifically point out in several areas that the numbers are general. Individual metabolism varies widely, Amagi. It’s not as simple as adjusting your carb/fat/protein ratio. This contributes - it is a factor in adjusting your metabolism - but it is not a silver bullet for healthy weight loss.

You say that calorie counting is virtually useless, then say that one calorie does not equal another, and then say if you adjust the caloric ratio of macronutrients you will eat fewer calories and lose weight.

What you’re saying requires adjusting the calorie count to the individual metabolism. This works, if a given metabolism responds in a particular way to the ratio adjustment. This is not universally the case. Some people have had wonderful results with Atkins, others have had keto miracles.

What it boils down to is that you need to burn more calories than you take in. You can do that with finesse and tune your diet to your metabolism (diy Soylent, smart eating, etc), or adjust your metabolism through your diet (keto, Atkins, etc.) You can also do that by increasing your physical activity to the point that you’re operating on a caloric deficit.

As to building muscle on a caloric deficit, it’s possible, but requires timing protein intake during recovery at regular intervals, and muscle gain is minimal. It’s more productive to do intense aerobic exercises - bodybuilding is very inefficient.

Calorie counting works. Basal metabolic rates are tricky to calculate, and individuals will burn fats, proteins, and carbs at different rates. When you highly weight a particular macronutrient, you’re adapting your metabolism to optimally burn that particular macro, and you can gauge your BMR more precisely, and adjust your activity levels more precisely.

With a “balanced” diet, you need to account for intake levels. If you take a lot of carbs, then work out later in the day after those carbs have been stored as fat, your body needs to release enzymes that in turn convert the stored fat to energy again - whereas an intake of carbs has a more direct conversion to glucose that’s released in the bloodstream. Your body will take the most efficient route (barring disease or disorder) to obtaining energy.


Saying caloric reduction is the key to weight loss is like saying putting less fuel in your car is the key to it getting better gas mileage. A car that gets better gas mileage empirically uses less fuel, sure, but it’s the complete wrong angle for adequate understanding of what’s going on. That’s not a perfect analogy, but I hope it illustrates the point- if you’re eating the wrong foods, you won’t be able to eat little enough to lose weight. If you’re eating the right foods, you can gorge yourself, feel full all the time, and still lose weight. Count your calories later and you’ll discover you are actually eating fewer calories in the latter example, but you’re full and satisfied because your body is getting adequate nutrition.

Your body gets hungry for a reason, and given proper fuel, it’s really good at telling you when it needs more. Your body counts calories as needed- it does all the math for you. The issue is, if you’re spiking your insulin levels all the time, your body can’t access many of the nutrients it has consumed, so you’re hungry again while also getting fatter. As you said, metabolisms are different, and one person may get fat on a diet where another remains thin, but I challenge you to find someone reliably eating a low carb/high fat diet that has remained fat for long.

I stopped eating virtually all grain and sugar about 6 months ago, and immediately lost 35lbs of fat, at a consistent ~2lbs/wk. I put in no additional exercise, didn’t count a single calorie, and ate until I was full, as much and as often as I wanted. My girlfriend did the same a couple years ago and lost about 50lbs. My wife did the same and lost 15, bringing us all to our optimum weights. There are countless examples across the web of nearly effortless weight loss according to this strategy- and the biochemistry tells us why. Grain and sugar has extremely low nutrient density and extremely high carbohydrates.

So why am I here, you might ask? I recognize a diet full of organic meats and vegetables is extremely healthy, but it’s not sustainable with a world population of over 7 billion people. Either we need to depopulate, or we need to explore more sustainable methods of feeding that many people- and it’s my hope that soylent, with the proper nutrients, could work toward fitting that bill. I just want to make sure the nutrient profile is chosen correctly according to modern science, not done according to the bullshit pseudosciencey garbage fed to us by the FDA, propogated by discredited research and corporate lobbying.


The latter statement is true. The former is off the wall. Waaaay bad analogy, such as to be completely without value to the context of the conversation.

Your family will have similar metabolisms because you’ll share similar gut microflora, cultural adaptations, and lifestyles. This means similar diet changes will likely have similar impact. I’m glad your diet change worked for you! The fact of the matter is your body burned more calories than it took in.

Thats how losing weight works. What is stored as fat gets burned up when your body doesn’t have enough immediately available energy.

Calorie counting only works when you have a reliable, sound BMR. Random BMR XYX off the interwebs is not going to suffice. It will take research, or a visit to a competent doctor or nutritionist.

Not sure what you’re talking about. Carbohydrates are not sugar. Nor are they grain. Nor do carbohydrates have a direct causal relationship to any sort of ill effect in a healthy metabolism. You’ve got a flawed view of “biochemistry” as some sort of rigid system that requires a particular fuel to work optimally.

It doesn’t. We’re flexible, and adapted to consuming a diverse range of nutrient sources. While we can survive on high fat or high protein or high carb diets, we’re equally able to consume a balanced mixture of the 3. Soylent approaches that balance.


You’re missing the point, again and again, but I’m not sure how I can explain this any more clearly. I wish I had the time right now to troll youtube for a suitably educational video- perhaps if I have some time in the next week I’ll get around to it. In the meantime, I cannot recommend highly enough the book I mentioned earlier. I know the chances of you going out, buying, and reading a book recommended by someone you think is wrong has about a 0% chance of actually happening, but nonetheless, it is the best I can do right now. Sorry.