Dieting can weaken the immune system

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2nd June 2004… ?

The date is not a misprint. The findings are as accurate for NOW as for THEN. "A new study has found that “yo-yo dieting” – repeatedly losing, then regaining weight – may harm a woman’s immune system".

Researchers in the study, published on the 2nd June in the Journal of the American Dietetic Association, interviewed 114 overweight but otherwise healthy sedentary, older women about their weight-loss history during the past 20 years. The women had to have maintained a stable weight for at least three months before joining the study, which was funded by the National Cancer Institute.

The study, which found that long-term immune function decreases in proportion to how many times a woman has intentionally lost weight, measured natural killer cell activity in the women’s blood. Natural killer cells are an essential part of the immune system, killing viruses and leukemia cells, said Cornelia Ulrich, senior author and an assistant member of the Hutchinson Center’s Public Health Sciences Division.

The study by the Fred Hutchinson Cancer Research Center found that the women who maintained a fairly stable weight over several years had higher levels of such cells than those whose weight frequently fluctuated.

Those who reported losing weight more than five times had about a third lower natural killer cell function, the study found.

Only 5% of "dieters" succeed in taking weight off – and keeping it off.

Although the study suggests that “yo-yo dieting” is harmful, Ulrich stopped short of saying that people should stop attempting to lose weight BY MORE NATIRAL AND SCIENTIFIC MEANS.

“There’s clearly evidence that weight loss is beneficial for your health”, she said. “What we’re concerned about is this pattern of weight cycling where women go up and down.”

Exercise has been shown to boost immunity and temper some of the negative effects of weight loss on the immune system, Ulrich said.

Katherine Tallmadge, a spokeswoman for the American Dietetic Association in Washington, D.C., said that people should avoid popular low-carb and low-fat diets that can produce initial weight loss but rarely work in the long term.

"Don't be guided (or misguided) by the scale – rely on body composition and fat loss, not muscle loss!" Almost every diet will involve loss of muscle and fat. No one can afford to lose muscle and this loss means that you will have increased your fat ratio to muscle ratio – with disastrous affects!