calories: how low is too low?

[Guest stephanie]

Hi, guys -

 

I'm fairly new to CR but have read a ton on the issue and still haven't found a set caloric point below which one should NOT go. I'm vegan and have done a few green juice fasts to lose weight in the past(but am struggling with weight again: currently 5'6" and 190 pounds so have quite a bit to lose). I love how nutritious green juices and raw, vegan diets can be when planned well.

 

Thing is, when I plugged in a diet of green juices (spinach, cucumber, lemons) plus other raw, green veggies and a bit of hemp oil into CRONometer, I was meeting 93% of nutritional requirements in 700 calories. Hard to imagine ever only eating 700 cals a day, but if the central tenet in CR is to get all your nutrients from the lowest amount of calories possible (without dipping too much under a healthy BMI), then what's to prevent someone (especially like me, with some weight to lose!) from starting there?

 

If you're getting your nutrients on CR, how low is too low on the cals?

 

Thanks for any help you can provide. :)

Stephanie

[Guest Bob F]

As far as I understand , the medical community advises not to go below 1200 calories/day

[GenGenimney]

If you're female and getting enough protein, at 5'6" most medical sources support a bottom limit of 1000 cal a day.

 

Below that, you risk diverticulitis and losing muscle and organ mass unacceptably.

[GenGenimney]

Argh, I need to add...

 

1000 calories minimum for SHORT TERM weight loss only, and your max deficit (difference between eat and burn) should be your fat mass * 27, which has to do with the maximum rate of fat mobilization (which is 31+/-3 calories per pound).  Right now, my max deficit is 810 calories, so I'm usually eating a lot more than that because I'm active.

 

Your individual maintenance will be much higher than that, but how much higher depends on your activity.  I was eating 1700 cal a day and was fat because I wasn't active.  (Estimated from what I was burning per day, measured well by an activity tracker, and the fact that my weight didn't change.)  I've up my activity by a solid 400-500cal a day, now, and would be nice and slim at 1700 calories a day.

 

"Enough protein" at rapid weight loss and that height is 60-100g a day.

 

Check out the "body weight planner" at the NIH to determine how fast you would lose and what you would get to at different intakes.  A BMI of 15 or below is in the "absolutely bad, you're starving, don't do that" range.  You're unlikely to be in CR with an BMI above 23.  18.5-20 is a possible optimal range, but there are so many confounding factors that benefits for a healthy person might continue to accrue down to 17 or so.  I'm pretty hesitant to declare this as fact.  You should definitely closely track all your health signs starting at a BMI of 19.