Down side to LOW low calorie intake?

The last couple weeks there have been a few times where I've come in more than 500 calories lower than my target RDI (which I also set lower than what FS suggested).

So my question is, clearly it's helping to drop weight now, but am I doing myself a disservice long term?

Clearly I'm not going to be able to maintain a 1200-1300 cal diet nor do I intend to - I'm not really even meaning to now. Tonight it was more a matter of not wanting to eat a huge meal late (after 8pm), but on other days it's just worked out that way.

Should I be forcing myself to eat a bit more so my body doesn't revolt when I go back to eating normal amounts longer term?

It's tough to give you a lot of feedback about this since I don't know much about you except for the fact that you are 30 years old. How tall are you and how much do you weigh? Do you exercise regularly? If yes, what do you do? What's the quality of your 12-1300 calories? Do you log your food/calories strictly or do you just guess at things?

If you're attached to your bodily organs, skin, hair etc... it is best to eat more than 500 calories. Without enough fat and other important nutritional blocks you'll cause damage to your body, lose your hair, etc. You cannot get enough nutrition on 500 calories, it is physically impossible.

You do need to force yourself to eat the full 1200 calories. If you find yourself full then use things that are less dense as your calorie blocks, like fruit and vegetable juice and milk.

i did read your profile ... at 5'7", being as active as you say in your profile, you need a lot more calories than 700 - 1000 ... even if you hit your target, i still think you would need more. i have to believe, even after training for your marathon, etc. and not losing, it is more of too little caloric intake ... but, like erika mentioned, the quality of the calories you do eat matters too.

what does fatsecret say your RDI should be? Remember, based on losing 1 pound a week and your activity level, the RDI FS recommends is about 500 calories lower than what you should eat to maintain your weight.

@Erika - I'm just shy of 5'7 and I weigh about 151 right now. I have a medium to large frame so I'd like to get to the mid to low 140s. I exercise quite a bit - at least three or four days of running 4-6 miles, one day of one hour spin and one day of one hour eliptacle. I also try to do at least a half hour of weight training every other day (though, I could be better with this part). I try to log my food as closely as possible, so my calorie count should be pretty accurate. Food intake is probably a bit carb heavy, fairly low fat - could definitely up my protein - working on that as well. What do you think?

@Sherilyn - I eat AT LEAST 12-1300 calories a day, with a target RDI of 1800 which I'm often almost spot on with. My question was a matter of the days where I come in at 12-1300 - 500 calories less than my target RDI - whether this going to have a negative long term affect on my body and metabolism. I don't want to do anything that is going to shock my body. When I get to a point where I'm just trying to maintain my weight I don't want my body to revolt when I adjust to a more typical calorie intake. Fear not, I'm no where near starving myself and have zero intention of ever going in that direction. Hope this is more clear.

I think you should be fine, especially if you mix up the total calories from day to day. You are not going to go into starvation mode for a few days of low caloric intake (think about when you are sick and you don't eat much). But, you should make sure you are eating nutritious foods b/c if you are eating low calorie, then you are probably having a hard time getting enough vitamins and minerals. If you eat a lot of fruits and veggies, then you should be getting the vitamins and minerals that you need. I recently started eating more fruits/veggies with lunch and dinner and have found that I am filling up with those and don't have room for much else. I was eating <1500/day and now <1400/day, but could easily eat less if I took out my evening snack. I exercise twice daily (which is only a temporary situation, I think)

Maintenance is a whole nother ball game. I plan to gradually increase my intake but will focus on a diet that is mostly vegetables. I will plan to decrease my exercise routine, but will keep an eye on the scale in that regards. Maintenance is where the real motivation/dedication comes in- that is for the long haul!

Sorry, I misread that as sometimes you're only doing 500 calories not realizing you meant 1200 for the day.

I'm 5'7 and maintained my loss very consistantly for the over a year eating 1200-1600 calories a day during the week (m-f) and then allowing yself to go over on the weekends and not worry about what I was eating. It all evens itself out over the course of time and won't shock your body at all. 1200 calories is enough as long as you are eating quality foods.

APK623: There are some hazards to insufficient calories. You may end up deficient in some important or essential nutrients, both macro- (protein and dietary fat) and micro- (vitamins, minerals, phytonutrients, etc). This isn't necessarily going to be a problem, though, if you're still getting enough through a diverse and careful selection of foods.

Longer term, the more aggressive your calorie deficit, the more likely you are to have some undesirable effects on several hormones, and you're encouraging a slowdown in your resting metabolic rate, above and beyond what you'd normally experience from simply having less mass. This will make it easier to regain the weight in the future. You can help protect against this by occasional refeeds, eating at your maintenance calorie level once a week or so.

The most immediate risk, though, is probably losing lean mass, which you probably don't want for health, performance, metabolic, and aesthetic reasons. There has been an observed limit in how much body fat can be lost per day, and it is estimated at around 31 calories per pound of body fat. More than that, and you're very likely losing weight from your lean mass instead of fat.

Here's how that might affect you:
You are 5'7" and around 151 lbs. With those numbers, you probably don't have a very high body fat percentage, so we'll guess that it's, say, around 25%.
That would mean around 38 lbs of body fat. If the observed model is right, you would be catabolising lean mass if your deficit is over about 1150 calories. If you're eating 1200 calories per day, you will therefore be losing lean mass if you're burning about 2350 per day or more. And if you're 151 lbs with your activity level - there's a fair chance you're burning more than that.

Consider eating more on those low days; burning through muscle is just about the last thing you want on a diet. From what you've described, there's no guarantee that's happening, but it's a risk.

I would say to focus more on your protein intake, since you said that's a little low. Maybe if you focus on hitting a certain number of grams of protein, it will naturally increase your caloric intake as well.. I'm 5'11", 153 pounds, and also a runner/spin class/zumba girl - carbs are important since you're so active, but try to get that protein up also. I'm typically pleased if I hit 90g/day.. some days I'm up around 120g, a few days as low as 65g..

I guess the bottom line for me is if you can get enough GOOD calories by eating 1300/day, then don't force yourself to gorge on more if you're feeling satisfied.. There's no sense in eating a bag of chips and an ice cream treat in order to hit your RDI.. even though it's fun to be able to sometimes.. But if you can add in some extra protein/fruits/veggies to your day (maybe add a banana to breakfast, greek yogurt with lunch, an extra 1/2 chicken breast with supper or some cottage cheese for a snack?) then I would do that.

If you're getting enough fruits/veggies/protein in your day, don't fret.. but maybe look into a good multi-vitamin (other good supplements are Calcium/Magnesium/Zinc and Vitamin D - take at the same time) since you're so active.. It's always best to get nutrition right from the source, but a multi could be a good addition..

I completely concur with erika. Pretty much what I preach and practice as well.

There's some good advice up there.

The bottom line is that doing something occasionally is not going to hurt you at all. If you're 500 calories under your RDI three days a week then that might be an issue. If you do it once every few weeks, it's going to be no factor at all.

The real problem with undereating is that doing it on an ongoing basis will screw up your metabolism, and likely cause you to be undernourished. Just don't make it a habit and you should be fine.

I have read a lot of benefits to calorie cycling. As long as you are not hungry you shouldn't force yourself to eat more. If you are worried about nutrients, look into a good supplement.