You've got to hand it them; food manufacturers are a canny lot. Far from following the law of diminishing returns, they've worked out that products that curb our natural desire to pig out could prove to be the next best thing since oh-so-edible sliced bread - even if the science behind appetite suppressants leaves some experts hungry for more evidence.
"There's a lot of baloney," says Gary Frost, professor of nutrition and dietetics at Surrey University, who waits to be convinced that such functional ingredients can make a difference to the growing problem of "globesity", now affecting 300M adults.
"The whole area is fairly controversial and is full of some very good science and some fairly sensational stuff. It's difficult to pick a group of foods that you can confidently say will actually reduce your desire for a certain other group of foods."
That didn't stop Unilever putting £6.5M up front last year for Cambridgeshire-based Phytopharm to develop Hoodia Gordonii as a functional food ingredient and planting up acres of the ugly cactus in South Africa to supply its labs with an extract that tricks the brain into thinking the stomach's full.
Not surprisingly, Unilever, which has just paid a further £3.5M out of a total £21M to progress to clinical safety trials on a product that must prove credible in a sector peppered by quack claims, is pretty aggressive about defending its patent.
"Hoodia is already on the market [in the US]," says Unilever's Trevor Gorin. "And this is the worrying aspect. There are a lot of pills and supplements, particularly US-based. We have tested a lot of them and effectively what they are doing is duping the public. Chiefly, that's a concern for consumers. From a more selfish point of view, it damages a fledgling sector and will make it harder for us should we get as far as bringing it to market. Should we find anything that contains the active ingredient, we will be passing it to our lawyers."
According to Kavan Ranasinghe, business line manager for food and ingredients at DKSH, which is working with a number of ingredient suppliers on appetite suppressants, including Belgium company Orafti's BeneoP95 based on oligofrustose from chicory root, the problem for finished food manufacturers is often the ingredient's distinct lack of cultural history in the country for which it is intended.
"Whoever signed the Hoodia cheque off must be sweating," he says. "We would always go for ingredients with a natural slant that have a decent history of use, because once you start talking about cactus you end up going through the novel foods process, which can be expensive."
But with demand for functional foods ballooning as big as our waistlines, that's unlikely to deter the major players - including Danone, Kraft and Unilever, that are all involved in blue sky research and eager not to make the same mistakes as those that have gone before, including the manufacturers of the so-called fat magnet chitosan, derived from a polysaccharide found in shellfish, which has run into problems with both the US Food and Drug Administration and the UK's Advertising Standards Authority for making unsubstantiated weight management claims based on frugal scientific evidence.
Danone is believed to be working on special types of fibre that slow down the passage of food through the body, leaving you fuller for longer, while Kraft is experimenting with starch blockers or amylase inhibitors. Unilever, on the other hand, is one of several companies already incorporating fat-binding technology into slimming products that play with the body's ileal brake mechanism, switching off hunger pangs when undigested fat molecules hit the lower part of the small intestine. Typically, Unilever says, it convinces the body that it has consumed 500 calories, when, in fact, it's only eaten 190. Hoodia, on the other hand contains active ingredient P57, which works like a super powered glucose, sending messages to the hypothalamus that you're fit to burst.
Other non-applied research is looking at the effect short chain fatty acids, such as those contained in vinegar, have on hunger hormones and how incorporating barley beta glucans to reduce the glycaemic index of food can suppress the nibbles.
Dutch firm DSM's Fabuless, a patented emulsion combining palm and oat oils, which also steps on the ileal brake, is much closer to the UK market. Already being sold in two premium dairy products in Italy and Portugal - Latte Merano's Action Calorie Control 200ml drinking yoghurt and Adagio's 'young and wild' brand Versus as a 90ml dairy shot - it's caused a flurry of interest among functional drinks manufacturers, according to DSM's David Jobse.
"The diet market is one week after Christmas and one week before the bikini season, but people want healthy products all year round and are not prepared to compromise on taste. The flavour profile of Fabuless fits particularly well with breakfast foods," he says.
In the UK, the functional foods market breached the £1bn mark last year, according to Mintel, growing a spectacular 143% since the beginning of the decade, with sales of appetite suppressors, including pills, piling on an extra £1.2M. By far the biggest growth in value was among yoghurt and juice drinks, many of which have now jumped on to the own-label wagon.
"There's huge potential," says John Kurstjens, global marketing manager for Dutch-based Lipid Nutrition, which says it has also been approached by several companies looking to incorporate hunger-curbing PinoThin, made from Korean pine nuts and currently only available in liquid form, into dairy products.
"A lot of things are happening in the market. Consumers are very conscious about their health and are very open for it. To describe what the benefits are of these ingredients is not difficult," he says.
Professor Frost begs to differ. "It's not straightforward. There's obviously something that comes into play that tells you you're full, but, on the other side, humans have survived over many thousands of years because they have been able to eat at times when food is around to excess to get them through the times when there's less."
However hard the food companies strive, the Squirrel Nutkin factor is going to be tough to crack, says Frost. "The idea that there's this highly developed way of controlling your food intake is going to be difficult to find - we are probably more geared up to being an eating mechanism."
Which might help explain why obesity has increased dramatically, despite the huge parallel growth in demand for lower fat and other functional foods over the past 10 years.
What's been so obvious to generations of mums and apparently so obscure to food scientists is that our eyes are, after all, genetically programmed to be bigger than our bellies, which means sales of appetite suppressing foods are - ironically - probably set to soar.
"The cat's out of the bag, in that people want to eat indulgent foods without feeling guilty about it afterwards," says DKSH's Ranasinghe. "That opens up interesting areas for developers - even putting appetite suppressants in chocolate. And if you look at those products per kilo compared to similar products the margins are crazy." FM