The skinny on fast weight loss

The skinny on fast weight loss

According to nutrition experts TODAY spoke to, people who crash diet periodically may weaken their immune system in the long run.

Their opinion is reinforced by a study published in the Journal of the American Dietetic Association, which found that yo-yo dieting - the repeated losing and gaining of weight - may have a lasting negative impact on a woman's immune system.

In the study, researchers from Seattle's Fred Hutchinson Cancer Research Center conducted tests on 114 women. The results showed that those who yo-yo dieted had less "natural killer cell" activity compared to women who maintained the same weight for five years or more.

Natural killer cells or NK cells are vital to the immune system. A decrease in NK activity has been associated with increased susceptibility to colds and infections as well as an increased risk of cancer.

Crash dieting can also lead to the "release of toxins" in the body and this can result in a weakened immune system, said Ms Yondi Lee, a holistic nutritionist at Ascension Healing.

"When one gains weight, toxins can accumulate in fat cells. With sudden and dramatic weight loss, these toxins may be released into the blood stream. This can tax the liver during the detoxification process and result in lower immunity," Ms Lee said.

In addition, quick weight loss often leads to nutritional deficiencies that can affect one's natural defence system, according to Ms Joanna Tan, a dietitian with Changi General Hospital's Dietetics and Food Services.

"Studies have shown that many infections occur or become more severe when there's a lack of specific nutrients such as polyunsaturated fatty acids, zinc, Vitamins A, E, B and C," said Ms Tan.

Other ill effects of crash dieting may include wounds that won't heal properly and in the long run, osteoporosis.

This is because as a person's weight plummets, they may lose bone mass, said nutrition experts. Over time, this may lead to weakened bones.

Lose it slowly, steadily

A good, healthy diet programme should be "slow and steady", said Ms Lee.

"It should address what you eat, as well as exercise and other appropriate lifestyle changes such as sleeping at a regular time and cutting down on alcohol intake," she said.

In general, a person should aim to lose only four to six kilos per month.

Even though you may be eager to lose those extra inches, added Ms Lee, you should never have to starve yourself to do it.
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