weight loss and fat loss question

Question
Dear Dr. Zilberter,

I am curious about the connection between weight loss and the loss of muscle mass.  It seems that so many people have differing (and conflicting) views on this.  Most people seem to agree that, when you lose weight, you also lose muscle (to a certain extent).  Therefore, you should weight train while you're losing the weight to preserve (or increase) lean muscle mass so that your metabolism won't slow down and your weight loss won't plateau.  These same people also seem to say that, as long as you keep your weight loss to around 1 to 2 pounds per week, you won't lose muscle-just fat.  My question is, is it possible to go on a conservative diet (maybe a 200-500 calorie per day deficit), do some cardio (maybe hight intensity interval training) and lose 1-2 lbs per week with no weight training and still preserve lean muscle while you're doing it?

Also, I've heard that weight training is essential for "reshaping" your body.  To me, it seems that if you don't want a big stomach or flabby arms or whatever you should just lose fat, and once all that fat is gone, your body will be reshaped. Am I wrong?

My general question is this; is weight training essential for the type of weight loss in which the vast majority of weight lost is fat?  

Thanks,
Chris  

Answer
Chris,

You are right about the connection between preserving muscle mass and strength training during weight loss. However, this is also about diet composition, not only weight loss rate. To keep the lean body mass while losing body fat, one has to consume enough protein. For one thing,

Dr Sears (the Zone diet) recommends that for body weight 180 pounds, daily protein intake would work out between 127 g and 158 g.

Dr. Lemon (Journal of Applied Physiology, 1992) suggests 1.6-1.7 g of protein per kilogram of body weight for those doing strength training.

The minimal requirement for preserving muscle mass during rapid weight loss is described in the clinical diet plan called Protein Sparing Modified Fast. The diet allows only meat, fish and vegetables. It provides a caloric intake equal to or less than 800 kcal/day; protein intake ranges from 1.5 to 2.5 g per kg body weight per day.

You might want to read more:
http://dietandbody.com/weightloss/nfblog/?p=52
http://dietandbody.com/Tips/nfblog/?p=93

As to your question about "reshaping" -- it depends on one's standards I guess. I can imagine someone being skinny while having a poor body image if there's not enough muscles and motor skills to insure good posture and gracious movement.

So yes, I do support the idea that strength training of some kind or another is essential for such aspects of your health and body image as sparing the muscles and insuring sufficient metabolic rate.

Read:

http://bestofweightloss.com/subpage11.html
http://bestofweightloss.com/subpageHomeGym.html
http://bestofweightloss.com/exercise/2006_07_01_archive.html

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