"With low-fat diets, we see a lot of skinny fat, where they get lean, but their body fat goes up because they're losing muscle, " Jampolis said.

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In this case, the worm Caenorhabditis elegans (C. elegans) was found by scientists at Rutgers University in New Jersey, US, to losing its muscle mass and strength as it aged, without any accompanying loss in nervous system function.

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At most, Kim could probably lose an additional half-pound to pound a week, "but any more than that and she would probably be losing water weight and muscle, " Jampolis said.

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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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