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Question: Severe Caloric Restriction


I know there is a slowing of metabolic function during times of prolonged caloric deficit, but is there a ceiling to that number. Meaning, despite very low caloric intake, will the body 'switch' out of that mode and start using fat for fuel?

Practical example, a 6 foot male, 30 years of age about 190 eating 1,000-1,200 cal a day for a at least a half a year. Despite moderate exercise, will the bodies metabolism deregulate to adapt to that caloric intake and actually stall weight loss or even encourage fat gain?


I hope you're not the 6 foot male, 30 years of age and 190lbs eating 1000-1200 calories a day for 6 months...

In the example you gave above, I think it's safe to say that your body is storing anything you shove in your mouth as fat. I also think it's safe to say you've probably got some other imbalances going on and should give some serious thought to what you're doing to your body.

Lets change this up a bit in another example:

You're 5'6 and weight 225 and want to cut some bodyfat for summer so you look good on the beach. You currently eat a boatload of food (5-6k cal's a day) and work out hard in the gym. You're a monster in the gym, great strength and muscle development and just want to shed that little bit of fat.

  1. Consume 6-7 meals a day watching your diet and eating clean
  2. Reduce your calories slightly (my suggestion is 250-350 cal/day)
  3. Each week reduce your calories a bit more (again slowly)
  4. When you're in the gym, you really work your ass off.

If you do a set and can talk about anything afterwards, you are nowhere near the intensity level you need to be at. If a set calls for 10 reps and you bang out 12 the first set, then that's a warm-up set - your first set counts when you either fail on 10 reps, or do 9 reps and can't do one more. At that point, you can do a set and be gasping for breath between sets - there's the right intesnity level.

  1. Ensure you do steady-state cardio at the end of every weight training session for 20-30 minutes.
  2. Pick 1 day a week for high-intensity cardio and nothing more (no weights this day).

In a few months you notice that when you walk by, women are looking - and I mean LOOKING...

Continue the way you are, and people are looking, but wondering if you're an HIV patient...


I am not that guy, this just popped into my head as a scenario and the effects of it. Metabolic function and the way the body responds to things interests me greatly.

Expounding on what you said, what imbalances would exist in such a case, testosterone, HGH? What about long term damage, if any? Also, in a situation like that, would upping the calories too fast be overload, or would your body adapt within a few days and start to use fuel as it should?


In all honesty, I'd suggest looking up anorexia nervosa, as in the example you provided, someone that is severely restricting their calorie intake would/could end up in a borderline anorexia state. They'd have all sorts of imbalances that could lead to long term health issues.

I'm no expert in anorexia (quite the opposite), as the people I deal with on a daily basis are never in this state. Most cases, we're looking to have them put on weight.



Eventually the fat will be used, but only after a severe amount of muscle is catabolized and burned for fuel first. Basically, to get to that point, your body will strip the muscle down to the bare minimum for basic locomotion (this is part of your body's way of lowering your metabolism. Less muscle = less energy expenditure).

Also, when you start eating again, your body will replenish your fat stores before starting to build muscle again. It's all part of the human survival mechanism. Your body is pretty damned ruthless when it comes down to the nitty gritty. If you were stuck in a cave with your family and a pantry full of food, you'd logically ration out the food as long as possible so that everyone would have a better chance to survive. But your body? He'd kill and eat your family one by one, starting with the one that eats the most. And if/when he got rescued, he'd restock the damned pantry before worrying about anything else.

True story.


I'm not a doctor and I likely don't know what I'm talking about, but that said, over the past year (plus a few weeks) I've lost almost 100 pounds. My caloric intake isn't that extreme, it hovers in the area of 2500 a day. In the past year I've done a lot of cardio + weight training, in addition to diet.

My point in bringing this up is that, for me, I think that restriction is/was extreme and it might have effected my body's T levels. My T levels are low, having been tested twice in the last few months and they are in the gutter. I've talked with a doctor (an endo and another one) and both say that it might be related to the weight loss. Since I'm still losing weight, both the dr's I've talked to suggest losing more weight (30ish pounds) and then 'maintaining' weight for a few months and get my levels checked again.

My point for bringing this up is that you could be doing damage to yourself, hormone-wise. I don't know if my case is permanent (or if it's even related), but I just wanted to throw this in there.


Points noted. Hormone damage is an interesting point, even touched on in the 'best damn cardio' article just posted.

As alluded to in that article, metabolism and hormone regulation can be damaged in extreme cases. How extreme are we talking? I know of anorexic females who were consuming sub 700 cal diets for years on end coupled with several hours of cardio a day and they seem to walk away unscathed after psychological. Also, I've noted several doctors say the metabolism isn't as fragile as some would like to believe. No real point to this paragraph other than voicing my inner confusion on the spectrum of ideas this one topic generates.


I'm not sure how extreme is 'extreme' - I think it's individual. I know that when I stepped up my cardio last year (2 5k's a day, three times a week) that I set myself up for injury. I was dragging. I've cut back some and I'm still losing weight and (seemingly) retaining my muscle.

I suppose I bring it up as something to be aware of - I'm not suggesting that you might have an issue or that it is necessarily permanent. I don't know in either case.


The first time I lost weight I went from 215 to 180 by reducing calories to something like 2200-2500 a day. Then I wanted to keep losing weight, so I kept reducing my calories even though I wasn't leaning out. I ended up losing a lot of muscie, lowering my testosterone levels, and crashing and burning, pigging out, and putting on a lot of fat.

I couldn't figure out what was wrong until I really started to learn about how the body works. In short, the advice on this thread is good, pay attention :wink:


Excess cardio never seems to be the way.

Oh, and guys, I'm not the example in this thread, it was a totally hypothetical question to satisfy my own curiosity of the workings of the body. I did know a guy who could fit the hole, but he wasn't as extreme as my example. Come to think of it, more of my male friends have body issues than females I know.


That is indeed the best damn cardio article I've read.

For humongous bodybuilders, the game is played differently. But for the Average Joe or even someone on the large-ish side, that article is absolute gold.


x2. It has scientific reasoning behind the things that I've found to be true.


1 000-1200 kcal is too low.190 lb. male would soon enough turn to 1oo lb.


Guys go pick up this book, Good Calories, Bad Calories http://www.amazon.com/Good-Calories-Bad-Controversial-Science/dp/1400033462/ref=sr_1_1?ie=UTF8&qid=1287668000&sr=8-1 its excellent. Much better than Omnivore's Dilemma and a much deeper read on more than one topic related to food.

Anyhow I have a few little tidbits I've picked up in my reading about super-low calorie diets.

This is from the above book.

Back in the early 1940's they did a study, on men, a sample size of 36. Anyhow, they put these men on 1,600 calories a day for 24 weeks in an attempt to recreate the SEMI-STARVATION conditions that would be found in Europe following World War II. Read about the results of the study here: http://en.wikipedia.org/wiki/Minnesota_Starvation_Experiment#Goals_and_methods

Guys attempted and some succeeded with self-mutilation, had severe depression, and a whole shitload of other negative side-effects.... and thats on 1600 calories.

One of the best Ex Phys Books you can buy (Brooks Bioenergetics etc... book) talks about low calorie diets saying anyone on 1000 calories or less should be under supervision of a doctor. No distinction is made as to whether male or female makes a difference, but I'm sure for a big guy its even worse.


Well, my last post was deleted for linking to a 'competitors site'. So for those with the inclination to read an article pertaining to this subject, a real world case example, you may want to google '700 calories and obese'.