Beware of following fad diets to shed unwanted post-Christmas kilos - dietitians are warning that most of them do more harm than good.
Only one in four of 20 fad diet books examined in an Australian study meet with national dietary and public health guidelines, the Dietitians Association of Australia says.
Most were of questionable nutritional value at best and could lead to serious health complications at worst, study author Dr Peter Williams warns.
"The recent popularity of high protein, low carbohydrate diets is of particular concern as the study showed they rarely meet nutritional needs and are difficult to sustain in the long term," Williams says.
"If followed to excess, possible complications include dehydration, calcium depletion, weakness, nausea, inadequate vitamin and mineral intake and kidney problems."
In addition, most fad diets rely on the loss of water, not fat, meaning that lost weight is easily regained when the dieter returns to his or her usual eating pattern.
"We know that rapid weight loss followed by rapid weight gain can have adverse effects on the metabolic rate, making it easier to gain weight in the future," Williams says.
Features that help identify a diet as a fad rather than a sensible weight loss programme include the promotion or banning of a particular food or food group, an implication that food can change body chemistry and the promise of quick, dramatic or miraculous results.
Dietitians Association spokesman Trent Watson says any extreme diet is bound to cause damage over time.
"For example, bananas are good for you but if they're the only thing you eat then you're going to have health problems in the long term," Watson says.
"If you cut out a major food group you're going to end up with vitamin or mineral deficiencies.
"If you eat too much animal fat, such as in some of the high-protein diets, you increase the risk of heart disease and some kinds of cancer."
The best way to deal with the Christmas party season is to try not to over-indulge in the first place, he advises.
"Enjoy yourself, have a few drinks and eat a few treats, but follow a well-balanced diet on most days," Watson says.
"And of course, don't forget a bit of regular exercise."
© AAP
