How chocolate can help you lose weight

Can you indulge your sweet tooth and lose weight at the same time? If it’s chocolate you crave, then the answer seems to be: yes. That is the surprising conclusion of a study by German researchers published this week in the International Archives of Medicine.

Confusion reigns in the diet world, with conflicting recommendations for diets that range from high-protein to low-carbohydrate and even high-fat. According to many nutrition researchers, the problem is that these tools are too blunt. “What is important is the specific combination of foods in your diet,” says lead author Johannes Bohannon, research director of the nonprofit Institute of Diet and Health. “Just lowering the proportion of carbohydrates is not a reliable weight loss intervention because it has different physiological effect depending on the bioactive compounds in your diet.”

Chocolate is a rich source of bioactive compounds, particularly a group of molecules called flavonoids, plant compounds associated with several positive health impacts. But teasing out the possible effects of such compounds in your diet, and how it may interact with various diet interventions, is rarely studied. It could be that simply consuming chocolate in combination with dietary interventions has no effect, or it could make such diets even more effective in the right dose.

To test the idea, the researchers divided volunteer human subjects aged 19 to 67 into three groups: One group followed a strict low-carbohydrate diet, another group followed the low-carbohydrate diet and also consumed 42 grams of dark (81%) chocolate per day, and a control group followed their status quo diet. Besides tracking their body weight and measuring blood chemistry before, during, and after the intervention, subjects filled out questionnaires to assess sleep quality and subjective well-being, a key predictor of dietary compliance.

As predicted, the low-carb group lost weight compared to the control. But surprisingly, the low-carb plus chocolate group lost 10% more weight. Not only that, but the weight loss persisted, compared to the low-carb group which saw a return of the weight after 3 weeks—a classic problem in dietary interventions known as the “yo-yo effect”. The chocolate group also reported better sleep and well-being, and their blood cholesterol levels were significantly reduced.

“To our surprise, the effect of chocolate is real,” says Bohannon. “It is not enough to just consume chocolate, but in combination with exercise and reduction in carbohydrates, our data indicate that chocolate can be a weight loss accelerator.”The researchers suggest that high-cocoa chocolate has the potential to enhance other diets as well. “The best part about this discovery,” says Bohannon, “is that you can buy chocolate everywhere, cheaply and without having to believe diet gurus or purchase expensive nutrition products over the Internet.”

Press release from The Institute of Diet and Health

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Don’t you just love this press release? It is just the kind of thing to get some newspaper editors salivating and social media users sharing online. If it sounds too good to be true, I’m afraid it actually is. The chocolate-helps-you-lose-weight hoax was the brainchild of German television reporter Peter Onneken who pitched the idea to American journalist John Bohannen. They set out to prove how easy it was to get a dodgy scientific study published. In fact, the study did take place, but as we shall see, it was deliberately shorn of any scientific value.

Some people may find this unethical, but elaborate hoaxes are a tradition among sceptics. In previous posts I have mentioned how physicist Alan Sokal was able to get a bullshit article, Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity, published in an American cultural-studies discussion journal, Social Text. The spoof piece was made up of ideas and quotations from various postmodernist philosophers and full of mathematical absurdities, which the editors failed to spot. I have also featured the magician James Randi, who coached stage performer José Alvarez to pretend he was channelling a two-thousand-year-old spirit named “Carlos”. And who can forget science writer Dr. Ben Goldacre’s dead cat, Henrietta, who became a certified member of the American Association of Nutritional Consultants after Goldacre paid $60 to the Clayton College of Natural Health?

For the experiment Bohannon claimed to be Johannes Bohannon, Ph.D., a health researcher and lead author of the study. Onneken and his collaborator, Diana Löbl handled the logistics. They had a few thousand Euros to recruit research subjects on Facebook. They also required the services of Gunter Frank, a German doctor responsible for running the study, and Alex Droste-Haars, a financial analyst, to massage the data. The study was intentionally flawed with a ridiculously small sample size, measuring 18 variables (weight, sleep quality, and cholesterol levels among others) that naturally fluctuate in participants. The 16 subjects (5 men and 11 women, aged between 9 and 67) chosen were from Frankfurt, and were paid €150 to go on a diet for 3 weeks. They were divided into three groups – one was a low-carb. Another was low-carb plus chocolate a bar every day, and the final one was a control group who were told to follow their normal diet. The participants had to weigh themselves every day for the three weeks, and the researchers also took blood tests, measuring all the variables you can measure from a drop of blood. The subjects also filled out surveys about their sleep quality and well-being and physical complaints.

By the end of the study they had a mountain of data. The control group’s average body weight fluctuated up and down around zero. Both of the treatment groups lost an average of around 2.5 kilos over the course of the study. But the people on the low-carb diet plus chocolate lost weight 10% faster, a statistically significant result. Moreover, the chocolate group had better cholesterol results and higher scores on the well-being survey.

The amount of data was of course one of the problems with the study. If you have a small number of people and a large number of variables that you’re testing for, you’re more or less guaranteed to find something that will appear to be statistically significant. It is a tried-and-tested recipe for false positives. And If you don’t say ahead of time what exactly you’re looking for, then you can just pick up wherever random result you do get and claim that you have made an important discovery. In this case what varied was the speed at which the participants lost weigh, but the result could have just as easily been that chocolate improves sleep quality or lowers blood pressure or cholesterol levels.

Now Bohannon and Onneken wanted to share their “scientific breakthrough” with the world. They needed to get their study published ASAP. As it was such patently bad science, they had to avoid any kind of peer review. They had the perfect solution. For €600 Euros iMed.pub published it in their premier journal, the International Archives of Medicine, an open access medical journal.

What happened then? It did get picked by the German newspaper Bild and Britain’s the Daily Star. It also made it on to Cosmopolitan’s German website and both the German and Indian websites of Huffington Post. On the other hand none of Britain’s broadsheets were fooled. Nor was the New York Times. The story also failed to appear on a major national network. However, I’m sure that this kind of material does frequently get through. Just go to Ben Goldacre’s website.

Curiously, the Facebook page for the International Archives of Medicine featured a statement from Carlos Vazquez the journal’s CEO, claiming the paper was published by mistake and was only live for hours:

Disclaimer: Weeks ago a manuscript that was being reviewed in the journal “Chocolate with High Cocoa Content as a Weight-Loss Accelerator” appeared as published by mistake. Indeed that manuscript was finally rejected, although it went online for some hours. We are sorry for the inconvenience. We are taking measures to avoid this kind of mistakes happens [sic] again.

This appears to be a terminological inexactitude as the paper appears appears to have been on a number of weeks. What’s more there is apparently this email from Vazquez:

I’m contacting to let you know your manuscript “Chocolate with High Cocoa Content as a Weight-Loss Accelerator” has been pointed by our editors as an outstanding manuscript and could be accepted directly in our premier journal *International Archives of Medicine.

Bohannen’s hoax raises questions about scientific experiments. This has been an ongoing theme in this blog. The abovementioned Ben Goldacre is a trenchant critic of such practices by the pharmaceutical industry. In “Missing Data“, the first chapter of Bad Pharma he shows the tricks employed by Big Pharma so that clinical trials will reach conclusions favourable to the drug company. He describes publication bias, in which only tests with important results are published. If a lot of tests with inconclusive results are ignored, this will skew the results. If the trial seems to be producing negative data, it may be stopped prematurely and the results not published, or if it is producing positive data it may be stopped early so that longer-term effects are not examined.

Ultimately we have to look at the role of the journalists. If you’re reporting on a scientific study, you need to actually look at the paper. You need to talk to a source with real scientific expertise. They need to actually interview the people behind the studies, and they should seek independent researchers’ opinions. And a healthy dose of scepticism wouldn’t go amiss.

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