What really happens when you don't consume enough calories?

court0109 · February 2014

Hi Everyone,
I am just curious, last week I was under my calorie goal pretty much every day of the week. I would have a kale shake that I made in my Nutribullet for dinner, and by the time I was done with that, I was just too full to eat any more. Every time I finished logging, I got the "You are consuming too few calories" message. I guess I should have listened because when I did my weekly weigh-in on Friday I had GAINED a pound, even though I really was not eating very much that week. I know that there are some facts and details about WHY it is bad to eat too few calories, and I was hoping someone could break it down for me in layman's terms.
I should also add that while I did gain a pound, my measurements all went down, so i guess it is possible that I'm gaining more muscle. Anyway, I just would like to hear more about why it is important to reach your caloric goal each day.
Thanks!!

kk_140 · February 2014

I would say gaining from muscle if all measurements went down. No matter what a deficit is a deficit, you will continue to lose fat stores if you're at one. It could also have been a normal weight fluctuation.

Don't let anyone start throwing starvation mode at you. You would have to be eating dangerously low nutrients and calories for a very extended period of time for that to be a possibility.

jellybaby84 · February 2014

In my experience if you don't eat enough you lose weight.

Seems like simple common sense.

Only of MFP have I heard people claim that they are gaining weight because they aren't eating!

However, if you don't eat you will lose muscle along with your fat and end up like me - thin but struggling to get through an hour's gym class without the shakes.

WBB55 · February 2014

There's structures in your body that measure your blood composition. Cells in need send signals to your body asking for energy to grow and repair themselves. If the balance between those "send me energy!" signals and the saturation of available glucose in your blood are off kilter, your body tells you to eat. If you DON'T eat enough glucose (or things that turn into glucose) to meet your body's requests for it, then your body sends signals to fat and muscles that say "hey, if you have any extra energy laying around, the brain could use some right now." And your muscles and fat cells break down to provide your brain with glucose (and other byproducts).

However, if that balance between the "send me energy!" signals and your blood sugar levels is chronically WAY OFF for a long period of time, your body will not send the same messages as before asking protein and fat cells to release their energy stores. You'll still lose weight over time. But the signals are different.

kgeyser · February 2014

If she's getting that message, it means she's eating below 1200 calories a day. And no, she's not gaining muscle, it is impossible for any human being to gain muscle while eating at a deficit.

You don't say how far below 1200 calories you are and I can't see your diary. But consistently being under 1200 calories can lead to screwing up your metabolism, lack of nutrients, fatigue, moodiness, hair loss, losing muscle mass in addition to fat (remember that your heart is also a muscle), and many other very bad things.

If you are exercising, you should be eating back your exercise calories on top of your daily goal. And let's all be honest, if you are on MFP to lose weight, there is no such thing as "I can't eat enough." Our ability to eat enough and then some is why we're here; saying it's hard to hit the goal is more psychological than anything else. It seems counterintuitive to be able to eat so much and still lose, and it makes us feel kinda stupid to realize how easy it would have been to eat at maintenance and how much we really ate to put on the weight. But you really can eat plenty and still lose.

So eat more to be healthy, well fueled, and not scare the bejesus out of everyone around you with hangriness.

court0109 · February 2014

Thanks everyone for your answers! I certainly have no plans to eat as few calories as I did last week, and I know the importance of feeding my body with the nutrients it requires. I was just curious more than anything as to the science behind what actually happens in the body when a person doesn't eat enough.

TeaBea · February 2014

Thanks everyone for your answers! I certainly have no plans to eat as few calories as I did last week, and I know the importance of feeding my body with the nutrients it requires. I was just curious more than anything as to the science behind what actually happens in the body when a person doesn't eat enough.

Your body needs a minimum amount of fuel for basic function.....heart, lungs, kidneys, etc. BMR - basal metabolic rate. These are the calories your body would use if you stayed in bed all day.

When you don't give your body enough fuel (think macros.....protein, fat & carbs).....not "micros" - vitamins, minerals ......your body will have to choose.....fuel your heart or fuel existing muscle mass.

One week is not a big deal, but week after week.....not a good idea. Make sure your weight loss goals are appropriate for the
amount of weight you need to lose.

Pounds per week
75+ lbs to lose 2 lb range
Between 40 - 75 lbs to lose 1.5 lb range
Between 25-40 lbs to lose 1 lb range
Between 15-25 lbs to lose 1 -.50 lb range
Less than 15 lbs to lose 0.5 lbs range

bwogilvie · February 2014

If she's getting that message, it means she's eating below 1200 calories a day.

Technically speaking, it means she's logging under 1200 calories a day.

http://www.myfitnesspal.com/topics/show/872212-you-re-probably-eating-more-than-you-think

That post is an eye-opener. One study (linked in the post) found that even trained dietitians underestimated their calorie intake by more than 200 calories a day; the control group, more than 400.

What really happens when you don't consume enough calories?

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