This may sound stupid but I was wondering why it's bad to have too few calories (for example 800 instead of 1200 to lose weight).

I think there are a number of reasons -- here are two!

1) It's hard to get enough nutrients! Food fuels us and we need to get something out of it. 800 calories just isn't enough for us! Some doctor supervised diets are that low, but that is a medically supervised program where they pay attention to nutrition.


2) there's some thought that if your body doesn't have enough fuel that it will try to conserve-- hold on to everything -- because you might be starving. So it might then make it paradoxically harder to lose weight.

3) Your body can actually consume more muscle when you dip your calories too low. It needs fuel to run smoothly and when you dip below your basal rate, it is going to get that energy from somewhere. To burn more fat, and less muscle - you just can't go that low.

good question...800 vs. 1200 is quite a bit, but when people say adding 100-200calories, like going from 1600 to 1800..I wonder how much of a difference 200 calories really makes to our bodies.

I totally did not understand how eating more would actually help weight loss. I went through surgery and barely ate for like four days, I ate healthy but like barely anything. I lost five pounds! I was so excited. I decided that I would eat about 1000 calories a day so I was eating about 900-1150 a day and I was so proud of myself. I LOST NOTHING! I actually bounced around with the same three pounds for four weeks! I totally ignored what everyone was saying about how eating too little calories would not help with weight loss until one day I ate about 1700 calories by having two slices of pizza. Then for a few days I kept it around 1300-1400 and I lost two pounds! Plateau busted, Yeah!

Don't eat too little calories, it doesn't help for more then a few days.

I'm pretty sure having too few calories is not good for your organs either. Plus it tends to make me miserable You need some energy to maintain healthy functioning and muscle building, repairing things you might hurt when exercising, fighting off infections, etc. 1200 is way below maintenance levels for most people, so dropping below that can become dangerous.

Here is a case in point. I am a 6 year maintainer and I was losing more weight and didn't want to. So I slightly upped my calorie intake. When I saw I was gaining a little more than I wanted I reduced my calorie intake well several hundred calories below my originial daily intake but the weight came on even faster! The last 10 days I have been on bussiness travel and I've been eating 700 -800 more calories per day and I've actually lost 2.5 lbs.

To keep it short, extremely too few calories can make you can weight.

Eating too few calories seems to be why I'm here in the first place. Most people get overweight because they eat too many calories but I'm the opposite. When I started tracking my food on spark people I realized I was barely consuming 1000 calories a day if that, and it was mostly dinner and snacks, I rarely ate breakfast or lunch. Now I use my gowear fit and it told me to eat 2000 cals a day (and expend 3000, so a 1000 deficit a day). The first few days I was barely reaching 1500 cals a day and I felt stuffed. Now I'm used to eating that much and my body appreciates breakfast and lunch, plus the steady blood sugar levels I'm maintaining. PLUS, I'm steadily losing which is what I want to be doing!
It's a weird concept but it's true. You need to eat more to lose. Plus, if you're a past yo-yo dieter like me, your metabolism is likely shot and instead of losing pounds on a low calorie diet, your body will most likely immediately go into starvation mode, hold on to everything it can, and make you gain 5 pounds.
Finally, we're all here to be healthy and you know what that means. There are no fast solutions to be found in this journey we're all on- as impatient as I am ( I just want to be at GOAL already!) I know that this is the right way to go in order to be able to maintain my success.

The greater your caloric deficit, the more muscle that will waste away, and consequently the lower your metabolism will be. Rushing your weight loss will likely mean that you'll have to eat a starvation-level diet to maintain your goal weight when you finally reach it. Think about this, would you rather be eating 1800 calories or 1200 calories at goal?

One more here: stuttering on 1200, cruising at just over 2lbs a week on 1500.

wow, i'm amazed to hear your stories because i really thought the less you eat, the more you lose since you're creating a calorie deficit!
thank you all for the insight, I really really appreciate it

hah? well, your body need at least 1200 calories to provide you the energy you needed to do your activities. Just imagine if you only consume 1000 calories... your body not get enough energy for facing the day.... you will feel sick because not get enough energy...

I think energy level is part of the equation, because when I'm eating too few calories, it seems I barely have the strength or mental concentration to just not eat. If I'm eating a moderate amount of calories, I probably burn more calories just because I feel like doing more. I think that little things really add up without our notice, things like walking a bit faster or further, or doing a couple extra chores or errands or even sleeping a half hour less... They're not necessarily things you'd notice unless you had a pedometer on and really looked and wrote down everything you did and for how long.

Also, more than a day or two under 1200cal and I get starving. Like ready to eat my clothing starving. It is not fun.