15/08/2012 13:02 BST

Yo-Yo Diets Do Not Affect Long-Term Weight-Loss (PICTURES Extreme Diets)

Whether you call it 'yo-yo dieting' or 'weight cycling', the repetitive loss and regain of body weight is generally thought to thwart women's chances of losing weight.

Not only do experts agree that yo-yo dieters tend to regain any weight they lose as soon as they resume sensible eating habits, it's also been suggested that weight cycling could damage your metabolism, making it less efficient.

However, a new study by researchers at Fred Hutchinson Cancer Research Center, published online in the journal Metabolism, appears to show that a history of yo-yo dieting does not negatively affect metabolism or the ability to lose weight long term.

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"A history of unsuccessful weight loss should not dissuade an individual from future attempts to shed pounds or diminish the role of a healthy diet and regular physical activity in successful weight management," said the study's senior author Anne McTiernan, in a statement.

According to NHS figures, nearly a quarter of adults in England are obese, while just under a third of women, 32% and 42% of men are overweight. In American, two-thirds of the US population is currently overweight or obese.

Obesity is a known risk factor for many cancers as well as heart disease and diabetes.

A relationship between body fat and the production of certain hormones and inflammatory markers is thought to contribute to increased cancer risk.

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"We know there's an association between obesity, sedentary behavior and increased risk of certain cancers," McTiernan said.

"The World Health Organization estimates that a quarter to a third of cancers could be prevented with maintenance of normal weight and keeping a physically active lifestyle."

The study was based on data from 439 overweight-to-obese, sedentary Seattle-area women, ages 50 to 75, who were randomly assigned to one of four groups: reduced-calorie diet only, exercise only (mainly brisk walking), reduced-calorie diet plus exercise and a control group that received no intervention.

At the end of the year-long study, participants on the diet-only and diet-plus-exercise arms lost an average of 10% of their starting weight, which was the goal of the intervention.

The analysis aimed to determine whether women with a history of moderate or severe weight cycling were at a disadvantage compared to non-weight-cyclers when it came to losing weight.

Of the study participants overall, 18% (77 women) met the criteria for severe weight cycling (having reported losing 20 or more pounds on three or more occasions) and 24% (103 women) met the criteria for moderate weight cycling (having reported losing 10 or more pounds on three or more occasions).

Although severe weight cyclers were, on average, nearly 20 pounds heavier than non-cyclers at the start of the study, at the end of the study the researchers found no significant differences between those who yo-yo dieted and those who didn't with regard to the ability to successfully participate in diet and/or exercise programs.

The cyclers also did not differ from the non-cyclers with regard to the impact of diet or diet-plus-exercise on weight loss, percentage of body fat and lean muscle mass gained or lost

Other physiological factors such as blood pressure, insulin sensitivity, and blood concentrations of hormones such as leptin (which helps make one feel full) and adiponectin (which helps regulate glucose levels) also did not differ significantly among those whose weight fluctuated and those whose did not.

"To our knowledge, no previous studies have examined the effect of prior weight cycling on the body composition, metabolic and hormonal changes induced by a comprehensive lifestyle intervention in free-living women," the authors wrote.