Fat or muscle was used to fill in the area after tissue was removed.

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Secondly, losing weight too quickly when you don't have a significant amount of weight to lose can result in muscle loss as well as fat loss, which can decrease your metabolism and make it more difficult to maintain your weight loss.

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What appeals to Mr. Bartakovics (who has added 2 pounds of muscle and brought his body fat down to 10% in the past month) is how effortless the process is.

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Conversely, BMI may underestimate body fat in a very small-framed person, someone who has very little muscle mass, or a person who carries his or her excess weight mainly around the midsection and has very thin arms and legs (the so called apple shaped body type).

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Because many of the thin diabetes patients included in the new study were elderly, they likely had less muscle mass and more fat.

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But it's still a little low in calories and fat for optimal health, she said, and could lead to a loss of muscle mass, which is difficult to rebuild.

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