When it comes to serious testing of claims made by food manufacturers for products designed to promote weight loss, the proof of the pudding really is in the eating.

Professor Peter Rogers and his group in the School of Experimental Psychology are well known for their expertise in the field of nutrition and behaviour. Back in 2002, they were approached by Unilever when the food and consumer products giant was considering a new ingredient called Fabuless for its range of slimming aids.

Previously known as Olibra, Fabuless was first developed by Swedish company Lipid Technologies Provider and then marketed by Royal Dutch State Mines (DSM) who acquired Lipid Technologies Provider in 2006. Early studies had looked promising, suggesting that Fabuless might help people lose weight through appetite control.

Testing the theory

It appeared that tiny amounts of Fabuless, an emulsion containing palm and oat oils, triggered a phenomenon known as the ileal brake, a biological mechanism thought to increase feelings of fullness, or satiety, after eating. Whatever the validity of that theory, genuine benefits can only be established by carefully monitoring the calorie consumption of people eating meals containing the ingredient against those being fed a placebo. That is where Rogers and his team came in.

“In the end, you need to demonstrate an effect on behaviour,” Rogers says. He points out that it is easy enough to make people eat less than normal by making them feel nauseous or uncomfortable, but much more difficult to do that by mimicking normal satiety without any negative effects.

But while Rogers and colleagues did find a marginal effect with the unprocessed ingredient, those benefits disappeared when Fabuless was subjected to standard preparation and processing methods used by the food industry.

Reviewing ALL the research

So did Fabuless work or not? As Rogers explains, the value of any single experimental study is inherently limited, particularly in an area as tricky to test as food consumption. To properly establish its effectiveness required a meta-analysis, collecting together the results of all the experiments done so far and ironing out any anomalous results or flawed experimental designs.

By 2006, confident that it would back up the earlier positive findings, DSM had funded a meta-analysis by Rogers and the Bristol team. What they found was that the earlier studies, all done by the same group and showing a sharp reduction in calorific intake were in fact outliers. Overall, the various studies showed extremely marginal benefits, and only when Fabuless was used in its unprocessed, unrealistic form. Adding salt, other oils, emulsions or acids, or simply heating food containing the ingredient could all render it ineffective.

Consumer protection

Despite those findings, DSM did not abandon Fabuless and it can still be found in certain products. However, Unilever’s decision in 2009 to abandon plans to use Fabuless in its popular “Slim-Fast” range has proved highly influential. Particularly as Unilever was happy for the “null” result to be published and urged other companies not to use it. This would have had a significant effect in a market sector estimated to be worth an annual $13bn.

A scientific panel formed by the European Food Safety Authority (EFSA) concluded that a cause and effect relationship between Fabuless consumption and maintaining or achieving of a normal body weight “had not been established”. This was independently corroborated and the findings published in 2012.

“The key impact is that this research has protected consumers,” Rogers says. It seems evident that publication of the Bristol research limited dramatically the sale of a product the group had shown to be ineffective at controlling appetite. And with strict regulations from EFSA demanding a strong body of evidence before any company can use supposed weight-loss benefits to market foods, this is set to continue.