What ill effects might I get from eating 2000 cal/day if I need 3300 to maintain?


I’m a 315lb male. I try to be a bit active (exercise 4 times a week ideally, usually more like 2-3 (for 45-60 minutes a pop, decent mix of strength & cardio).

According to the calculator I need 3300/day or so to maintain my current weight.
I want to lose weight.

I am wondering if I am going to have horrible things happen if I drop my intake to 2000/day (one bag of soylent), or if I absolutely need to supplement that?
(I have good food available at work, but figuring out calories is tough.)


Normally you would want to see a doctor about that. I’ve gone 5 days on 0 calories a day, and I’m not dead. I personally would try it and see how I feel .


Depends on your height, weight (which you provided), age and excercise level (which you provided).

There are numerous calorie calculators on the web. They will tell you exactly how many calories you need in order to lose [x] pounds per month.

Another option, if you think tracking food calories too difficult, is to consume more than one bag of Soylent per day (assuming the calorie calculators recommend you consume more than 2000 calories/day).


You’ll lose about 2-3 pounds per week. Nothing terrible, but that is fast weight loss if you keep it up for weeks/months. Give it a try. You’ll probably be pretty hungry, so some small snacks would be fine and you’ll still lose weight at a good pace and good nutrition.


Personally, if it were me, I would consume the 2,000 calories of Soylent, and substitute either a good quality protein shake, or one meal of real food every day. Something like hard boiled eggs and fruit. Just as important as knowing how much to eat, is knowing when to eat. Eat often enough that you don’t feel hungry, even if you only eat a small meal; 4-6 meals per day. Of course, Soylent should do its part to keep you feeling sated.


6’ tall, 32 years old, 315 lb, ideally 4x 45-60 minute exercise sessions per week (realistically 2-3 most weeks), little other activity (park in a garage attached to my office, drive to the office, little walking during the day, little weekend walking).

The calculator here (http://diy.soylent.me/nutrient-profiles/calculator) indicates 3323 to maintain, 2520 to lose rapidly.


Lose weight but try not to aim to lose it ‘‘rapidly’’.


I saw this study in the past year (Myths, Presumpstions, and Facts about Obesity) that said losing weight quickly did not have the ill effects we were all led to believe and that people who lost the weight faster tended to keep it off longer than those that took the slow and steady route.


Really it seems like the issue with losing weight too quickly is more about starvation/nutrient deprivation than the weight loss itself.

@Morik, switching straight to 2000 cals overnight is probably more than I would cut for a guy of your height and activity level, but I don’t think it would really be a serious issue as long as the Soylent kept you full and feeling good.

I think the recommendation of ~2500 cals is a great place to start. You could try the Soylent but make that 2500 calories your ‘upper limit’ of in case 2000 calories of Soylent isn’t enough to fill you. You could easily get the extra calories from some mixed nuts, cheese and crackers, or some other delicious snack food that takes no effort to prepare.


My 2 cents is to consume the 2000 calories of Soylent and eat up to a 500ish calorie meal very high in protein. During weight loss extra protein will help you keep more lean muscle mass and increase the amount of fat lost. Over all you will lose the same amount of weight but keep more of your muscle in the end.


Hi Morik,

I’ll second genevens opinion that you should check in with a doc (a regular GP should be fine, no need to find a fancy dietary doc).

The “maintain” vs “lose” calorie calculators have always seemed a little suspect to me, and I have zero faith that they scale correctly at the low or high ends of the weight range.

Given your weight and activity levels it seems worth it to ask.


That’s why I call them guestamators :smile:


Also dont go lesser than the lower limit of any macro. Exercising while losing weight rapidly, could lead to lightheadness and sometimes fainting, so keep an eye on your electrolyte consumption too if you are sweating a lot.


I personally think you’ll be fine at 2000 calories. If your body needs more energy, it’ll begin converting fat storage. With that said, listen to your body.

I would look into figuring out your body fat percentage (caliper not scale), which will help figure out your lean body mass. Knowing your LBM will help you figure out how much protein you should be taking. I personally would focus on strength training 2-3 times a day to maintain muscle. Keeping as much muscle as possible will keep your metabolism fast.


@Altriox: Did you really mean 2-3 times per day for strength training, or 2-3x per week?


Sorry, yes full body strength training 2-3 times per week.


Yeah so right now I do:
2 days weight training with trainer. Functional movement focus, generally circuits or super sets, etc, of medium weight 8-12 reps per set. (We occasionally do higher strength days with high weight, 3-6 reps per set.)
Somewhat full body, sometimes focussed on one area.
E.g., today was step-ups, pushups, farmer’s carry w/ 135 lb, bent over sandbag rows (maybe 40lb?).
40 sec on, 40 sec off, one of each per circuit, 4 circuits. Then we did renegade rows & sandbag plank/drags for 20 sec on, 20 sec off (2 circuits).

That wasn’t atypical of what we generally do.

  • 1 day MMA class (grappling/wrestling & striking). Its exhausting and I’d say mostly cardio (though I am sometimes sore the next day depending on what we worked on)

  • 1 day cardio kickboxing class (essentially all cardio)


“Horrible” things will not happen.

Faster weight loss will happen.

You will, however, be very hungry - gradually more and more so as time goes on - and your workout recovery will not be at its best, and you may find it harder to sleep.

Consider taking in extra after a workout and the morning after workout days, to boost your recovery, if you find that it’s impacting you too much.

You’ll also need to get used to not being physically full, as well as not being chemically satiated by food - you’ll have neither a full belly, nor a full calorie count, when you cut calories that hard and start on liquid food at the same time.