Dispelling diet myths

For people looking to lose weight, there is no shortage of advice.  Unfortunately, not all of it is sound.  Everyone knows that one person who lost a huge amount of weight on some fad diet or another, and magazines and websites are populated by celebrities with perfect bodies and bizarre eating habits.  Some even go so far as to offer “scientific” explanations for how their preferred diets work.

But science is about measuring outcomes, not just postulating hypotheses.  An explanation can only be called scientific if it has undergone rigorous testing and analysis.  Let’s say, for example*, that a celebrity chef makes a claim that eating 50 mg of kale extract each day for a month leads to significant weight loss because it’s a powerful anti-oxidant.  It sounds plausible, right?  So, how can you test this claim scientifically?  It’s no good saying that John Smith tried it and he lost 10 kg in a month, because John’s weight loss may have been due to something else.  Remember Luciano Pavarotti the opera tenor?  Everybody thought he lost a lot of weight because he changed his diet and was exercising; it turns out he lost a lot of weight because he had pancreatic cancer.  So we need more subjects to try the kale extract to be able to measure the effect reliably.

But we know that simply enrolling people into a health trial can lead to health improvements for a variety of reasons, including the placebo effect.  So we need another group of subjects similar to the subjects undergoing the trial to be the control group, with the only difference between them being the kale extract.  If the group taking kale extract lose a signficant amount of weight, and the control group do not, then the weight loss may well be due to the kale extract.

But clinical trials like this are not easy to design, conduct, or analyse, and any number of problems at each of these stages may cast doubt on the findings in unpredictable ways.  In addition, clinical trials addressing the same question in different ways can lead to confusingly different results.  So how do you tell the difference between good, effective advice and celebrities selling magazines?

As it turns out, this course developed by experienced dieticians at the University of Newcastle is a good place to start.  It’s not just learning about what to eat, but learning to understand the science of nurtition and weight loss, and how to tell effective from sham interventions for weight loss.  That is what sets this course apart.

*This example is used only to illustrate a point; no claim is being made about the effects – or lack thereof – of kale.

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