Many people confess that they've "tried every diet in existence", that they've "lost weight only to regain it again and again" and that they've been doing this for long periods of time – in some cases for up to 20 years.
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This vicious cycle of weight loss followed by weight gain to the same or higher weight has been dubbed yo-yo dieting. In view of the obesity epidemic that is overwhelming the world, it is particularly relevant to ask if this cyclic loss and gain of body weight can have detrimental effects on health in general.
A recent edition of the Arbor Clinical Nutrition Updates attempts to answer the question, "Is 'yo-yo' dieting bad for you?"
The findings of this Nutrition Research Review indicate that yo-yo dieting is potentially harmful to general health and that it can decrease immunity, predispose individuals to exponential weight gain and increase the risk of developing high blood pressure.
Yo-yo dieting and immunity
An American study conducted among 114 overweight women after the menopause investigated if there was a connection between repeated weight cycling in the past 20 years and their present immune status.
Although the time period during which the women had lost and gained weight was very long and some of them may not have remembered clearly what happened during the previous 20 years, the study did show that women, who reported that they had repeatedly attempted to lose weight, had lower natural killer cell immunity (a criterion of immune reaction).
Yo-yo dieting and continued weight gain
Experts have always suspected that anyone who loses weight over and over again, only to regain it just as quickly, will harm his or her weight control mechanisms.
Analyses of some of the data obtained from the so-called Nurses Health Study (one of the most comprehensive nutrition and health studies ever conducted in female subjects), found that 965 women who admitted to being "weight cyclers" tended to gain more weight than the 967 women who did not lose and gain weight repeatedly.
The women who were classified as "severe weight cyclers", which meant that they had lost at least 9 kg of weight three times in the previous four years, on average gained 4,7 kg more weight than the women who did not go in for weight cycling.
These results confirm the suspicion that people who lose weight and gain it back again will end up weighing more than they did when they started this self-defeating exercise.
Yo-yo dieting and hypertension
A German study among more than 12 000 adults found that in obese individuals with a BMI exceeding 30, weight fluctuations related to yo-yo dieting predicted the risk of developing high blood pressure or hypertension.
Another study showed that weight cyclers tended to reduce weight and lower blood pressure less effectively than patients who did not lose and gain weight over and over again.
Not all negative
The studies reviewed in the Arbor Clinical Nutrition Update (2005) did not all produce negative findings about yo-yo dieting. There does not seem to be an increased risk of diabetes in these subjects and there is no conclusive evidence that yo-yo-dieting will predispose individuals to a higher risk of heart disease or overall risk of death.
Why does yo-yo dieting occur?
The burning question is of course, "Why do some people tend to regain weight that they have lost and land up in the vicious cycle of yo-yo dieting?"
At the moment, experts don't know the answer to this question. It has been suggested that some individuals have certain built-in factors that make it difficult for them to sustain weight loss.
A number of factors are being investigated, namely insulin resistance and development of the metabolic syndrome, 'thrifty genes' and over-efficient energy regulation, but the research is still in the early stages and we don't know for sure why some people become yo-yo dieters, while others do not.
What can be done about yo-yo dieting?
If you have been caught up in the endless round of slimming, losing weight, regaining weight and then having to start all over again, the following points may help you to break out of this vicious cycle:
Try to change your lifestyle completely. Don't think that when you have lost weight that you can now return to eating anything and everything again. Stick to your diet for the rest of your life. This may sound like a prison sentence, but in the long run eating a healthy, low-fat diet that is rich in dietary fibre and protective nutrients is also going to pay off with other health benefits such as a decreased incidence of all the degenerative diseases.
Continue doing exercise for the rest of your life. Once again, this is not a prison sentence, and it will ensure that you don't regain the weight you lose with so much effort. Exercise also has a long list of health benefits such as preventing certain cancers, improving blood circulation, boosting your mood and preventing depression, strengthening the bone structure so that you don't develop osteoporosis, and motivating you to stick to your sensible eating habits.
Avoid all "instant" or "fad" diets, all slimming pills and potions, and any regimen that you know full well is not sensible and balanced.
If you have been a yo-yo dieter for as long as you can remember and your attempts always fail, consult a clinical dietician. Use a sensible, balanced, energy-reduced, low-fat diet and exercise to lose weight. Then stick to that healthy lifestyle for the rest of your life. – (Dr Ingrid van Heerden, DietDoc)
(Reference: Arbor Clinical Nutrition Updates (2005). Is 'yo-yo' dieting bad for you? Issue 215, June, 2005, p1-3)
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