Very Low Calorie Diet Vs Normal Calorie Control diet

Hi,

I keep reading about how we need to keep our calories high enough to make sure we have enough to burn (short explanation) and remain fit and healthy. 

I also have been reading about VLCD's (like lighter life) that are often prescribed by Doctors for very overweight people.

My question is this... IF we need to eat at least 1200 calories a day to ensure we reduce weight healthily (workouts / excecise etc.. depending) and VLCD's (600 - 800 calories per day) are dangerous, then why are they recomended by Doctors?

IF a VLCD is bad for you and can make you dangerously ill, then why is it Ok for very overweight people?  Surely we all need similar amounts of intake (again depending on excercise, health etc..)

Any one have an answer... I am really interested, not just starting a debate between the two...

Thanks

According to Wikipedia:

"A VLCD is typically undertaken by an obese patient who wishes to lose a lot of weight quickly, as the risk to health that obesity presents is considered much greater than any risks of the diet itself"

I guess that in cases of extreme obesity, a VLCD is the lesser of the two evils...

It's a question of relative risk.  If someone is so extremely overweight that their health is already compromised, a few weeks or months on a medically supervised VLCD  is the lesser of two evils.   There's a similar argument for gastric surgery.   Note the words 'medically supervised' (not a Lighter-Life sales rep).  People in both those categories need a lot of monitoring and their diet supplementing to ensure that they don't fall prey to malnutrition and other health problems. 

For those people who aren't in immediate danger, the VLCD or surgery is overkill.... too risky.

When you diet your body doesn't only get calories from your food intake, it also gets calories from the stored fat in your body.  So if your calories are below 1200 then  your body takes more calories from stored fat to make up for it, but it can only take so many calories from fat.  The more extra fat you have the more extra calories it can take from them every day, so people who are very overweight can live on a lower calorie diet because their body gets more calories from their extra fat.

http://article.wn.com/view/2009/06/16/Weightl oss_surgery_seen_to_impact_bone_density/

I saw a story not too long ago about a link between bariatric surgery and bone density loss.  It seems that even with medical supervision and supplements that gastric surgery combined with VLCD is doubling the risk of bone breaks -- this needs to be verified with more studies.

I know that in extreme cases of obesity that VLCD with or without surgery is considered the lesser of 2 evils, but I wonder if that is really true?  If the medical community intervened with the same level of supervision that is necessary for bariatric surgery by monitoring moderately restricted calories, psychiatric therapy, and physical therapy would the very obese be just as successful with fewer risks?  I am not a doctor, but I wonder if they are not just falling prey to the quick fix for a chronic problem that plagues so much of Western medicine.

It does make me very happy that as out of control as I let my weight get I didn't face these decisions for myself.

To add to reply #3, the body can only take 31 calories per pound of fat per day (under ideal conditions; in practice, the number is smaller).  So, it can't be argued that "well, I have fat; I'll let my body use that".  If it needs more energy than that, it'll start breaking down muscles - including really important ones like the heart!

Also, medical supervision is necessary to minimise the effects of malnutrition from undereating.  As was noted in the first couple of responses, it really is a case of somebody being *so* sick from being morbidly obese that it becomes advisable to take the risks of the very low calorie diet because they are relatively less than the health risks of being so heavy.

Did you ever read the package inserts that come with prescription medicines?  It always lists the side effects, then makes a statement that your doctor has determined that the benfits outweigh the risks.

If you read about people who use this as a lifestyle, you'll be surprised to find out that what they are talking about is living on 1200 to 1800 calories a day, even when weight loss is not needed. 

All the research on longevity was done on animals like mice.  Part of the reason they lived longer was that they lost the ability to reproduce.  Since mice bear young very quickly, many times in their lifetimes, simply removing the stress of giving birth would do it. 

Who would want to lose their reproductive ability?

Original Post by gerbology:

When you diet your body doesn't only get calories from your food intake, it also gets calories from the stored fat in your body.  So if your calories are below 1200 then  your body takes more calories from stored fat to make up for it, but it can only take so many calories from fat.  The more extra fat you have the more extra calories it can take from them every day, so people who are very overweight can live on a lower calorie diet because their body gets more calories from their extra fat.

 This statement is quite misleading.  Here's a better explantion of what happens in starvation, from Ask Mary, our nutritionist.

The body burns muscle to meet the needs of the central nervous system.  That system, which accounts for at least 20% of calories burned, can only burn glucose, a carbohydrate  The body doesn't really store glucose, but protein, from the muscles, organs tissues, and cells, can turn into glucose, while fat cannot.  Protein breakdown continues until the metabolic rate shifts to burn fewer calories from all sources.  That shift is familiarly called "starvation mode" and it is a life-sustaining adaptation. To forestall starvation mode, lose weight slowly, do muscle building exercise to offset muscle loss, and eat about 20% of your calories from protein.