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Why eating too little calories is a bad idea.....

tinkerbellang83 Posts: 9,081 Member
edited June 2017 in Health and Weight Loss
I have been on MFP since 2011 but only used it properly and the forums for the last 6 months, the number of posts I see (mostly) from women eating 1000 calories and under or netting less per day when they could lose by eating a higher and healthier intake is heart-breaking. When I used MFP in the past and was a serial starter, I have eaten quite low calories (Around 1300) because I hadn't really a clue what I was doing so I hope this post goes some way to educating those who think that the only way to lose weight is to starve yourself and it will save me typing out the same response repeatedly :lol:

What is a healthy weight for you and what rate of loss is healthy?
The BMI range is a good place to start. You can calculate your BMI here
US & UK departments of health* recommend a steady weight loss of 1-2lb per week for those who are obese. If you have any medical concerns it's best to consult with your doctor.

The science behind weight loss/maintenance/gain
If you're new to MFP you may or may not have heard the term CICO being thrown around.
CICO is an energy balance of Calories In & Calories Out.
To lose weight your CALORIES IN must be less than your CALORIES OUT (CI<CO)
To maintain weight your CALORIES IN must be the same as your CALORIES OUT (CI=CO)
To gain weight your CALORIES IN must be more than your CALORIES OUT (CI>CO)

Understanding how your calorie allowance is calculated8kn2ubmrqx6s.jpg

Eating low calorie but still not losing weight
There are many posts already on this subject but in summary, those who are eating low calorie and not losing weight, for the most, this is down to logging inaccuracies either in underestimating calories in or overestimating calories out. Using measuring cups or estimating/eyeballing portion sizes are very inaccurate ways of calculating the calorie content of meals. Using the MFP database/Machine Readings/Non-HR fitness trackers for calorie burns can also be an inaccurate method of determining burns.

Net Calories and Eating Exercise Calories Back
Your initial calorie allowance is essentially a net figure - the way MFP is set up you are intended to eat back your calories burned as they are not accounted for in the calculations to acquire the figure. If you ate none of your exercise calories you are putting yourself in a larger deficit than you have set yourself in MFP. This may be ok if you're set at lower rate of weight loss, however if you're already at 2lb per week loss (1000 calorie deficit) then you could be getting less food than you need to fuel your body sufficiently. Going back to "Mildred" above if she didn't eat any of her calories back she would be netting under 850 calories on her active days and this would no doubt impact her energy levels and her running performance.

The Negative Effect on Weight Loss from Undereating
Some people may well be able to stick at a 1000+ calorie deficit for long periods of time, however for a lot of us what actually happens when you are being overly restrictive is that we can only manage it for a short while because it's too drastic and we are simply hungry so we decide to pack it in and go back to the way we were eating before and end up in a vicious cycle of binge and restrict that doesn't actually achieve anything.

The Short & Long Term Effects of Undereating Without Medical Supervision
In the short term undereating can have the following effect (this is by no means an exhaustive list):
  • Mood Swings
  • Fatigue
  • Constipation
  • Hair Loss
  • Menstrual Irregularities
  • Dizziness
  • Brittle Nails
  • Poor Skin Condition
  • Headaches

In the long term it can have far more negative effects, such as:
  • muscle loss
  • gallstones
  • electrolyte imbalances
  • organ damage
  • bone density loss
  • vitamin/mineral deficiencies
and whilst you might feel fine now, there is not always an advance warning of the long term effects.

Other useful posts that can be read in conjunction with this one:
Accurate Logging
Weight Loss is Not Linear
Why am I not losing weight?

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  • sak20011
    sak20011 Posts: 94 Member
    I am on my second start. my first, I lost no weight. Recalculated my TDEE to reflect the fact that yes, even though i work out a few times a week, I'm otherwise not that active--so its 1440 (I'm 5'1" and 125). . That puts me at 1200 to lose 1/2 lb a week. I'm going a bit under some days that I can have a nice meal out or two this week. My goal is to lose 5-8 pounds, but once I have a new 'set point' I'd really like build up enough muscle/get enough exercise that I can maintain on 1500. I know this seems low, but I am a 40 something short woman...