Designing Foods for Weight Loss

The biomarkers discussed in the review include short-term drops in blood glucose (which tell the person to begin a meal), plus longer-term changes in the level of the hormones leptin (which signals negative energy balance) and ghrelin (which appears to have an effect on both long- and short-term energy balance). These biomarkers are hard to measure, and their total effect is still somewhat unclear. But what is clear is that the study of satiety is moving along at a fast clip.

Pulling the trigger

Other triggers of satiety have been reported by testers of Nestle Co.'s Lean Cuisine line. Those conducting the study found they had to ban outside publications containing pictures of foods. The subjects testing the products were required to wait in the facility and report every 30 minutes how full they felt. If they saw pictures of chocolate cake or other foods, they felt hungry earlier.

"If we only judged hunger by how full the stomach was, we'd never eat dessert," says Mark Friedman, a director at Monell Chemical Senses Center, Philadelphia. Friedman has expressed doubt about the food industry's ability to develop products that solve all of the mechanisms that contribute to hunger.

Because of the difficulty in translating the health effects into viable products, a number of researchers measured the feelings of satiety by different methods to produce an index called the Satiety Index. Suzanne Holt of the Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia, used white bread as a baseline and compared 240-calorie portions of various foods, as consumed by volunteers who then rated their feeling of fullness every 15 minutes over a period of two hours.

Although not all of the findings were landmark, they may be especially important to companies providing foods for dieters. Or, for that matter, for school or office lunches or anyone who wants to avoid the 2 o'clock "slide" and resulting dash for junk food.

For the interested food processor, specific ingredients included in complex foods can make a big difference to the dieter. Holt found simple category designations, such as "cereal," "vegetables" or "fruit," can be misleading. "You can't just say that vegetables are satisfying or bakery products aren't, because there can be a two-fold difference between similar foods," she declares. For example, under the category of starch, pasta, bread, potatoes or rice elicit different results in how hungry someone feels after eating them.

Compared to the CSIRO satiety value of 100 for white bread, the same caloric count of brown rice provides 155 percent of the satiety and white rice 119 percent. And the same caloric serving of boiled potato provides 323 percent of the satiety of white bread.

The greatest thing since…

Interestingly, some food companies, including ConAgra Foods Inc., are investigating ways to improve the satiety of foods, such as bread. A recent patent assigned to ConAgra describes a new bread product as "having an increased or high satiety index (SI)."

The high-SI bread's ingredients include a wheat flour, a grain/seed source of soluble fiber and a processed source of soluble fiber. The SI bread product may also have a low glycemic index (GI).

One of the inventors listed on that patent, Elizabeth Arndt, is manager of product development for ConAgra Mills (www.conagrafoodingredients.com). Arndt believes the Satiety Index is a distillation of recent diet thinking, culminating in better consumer understanding of whole grains and their full value. "The low-carb trend a few years ago, followed by the 2005 Dietary Guidelines and MyPyramid, became a turning point for consumers. They understand that not all grains are equal," she says.

Arndt develops new products that provide whole grains throughout the meal. The patented bread also contains ConAgra's Sustagrain - a waxy barley product that can be used to increase fiber in all kinds of products, including pizza crust, pasta, vegetable patties, rice pilaf, tortillas, cookies and brownies.

Sustagrain also can be used in some beverage applications. It's a companion product to ConAgra's wheat products, including Ultragrain, a white flour with whole grain content. The patent covers a variety of formulations. It should also be noted that ConAgra is the maker of Healthy Choice bread.

Technique follows trend

Much of the interest in the Satiety Index follows interest in the Glycemic Index, which is a recent variation of the low-carb craze. The low-carb trend trend initially moved sales of some foods up by about eight times their normal levels. Sales subsequently leveled off and dropped. But these products changed American attitudes. More consumers are seeking out whole-grain foods, foods with more fiber and lower-calorie products in general.

Following the trend, ingredient producers started to look beyond white flour. To that end, ConAgra, ADM and Cargill produced white flours containing the whole wheat berry. ConAgra's Ultragrain is made from white wheat, microground so the white flour resembles ordinary white flour. ADM's is Kansas Diamond white whole-wheat flour. Cargill's Horizon Milling produces a white wheat flour that can be used to produce a whole-grain loaf.

To boost fiber content, another ConAgra company, Gilroy Foods, introduced a variety of vegetable purees so dense they don't freeze solid and can be measured straight from the freezer. These products can add significant amounts of fiber to products, in addition to antioxidants and flavor. And they can increase satiety.

Other companies, such as Unilever, are focusing on the basic mechanisms of weight control. The company has been working on a metabolic process called the "ileal brake mechanism." This concept, which uses fat capsules and other ingredients to delay fat metabolism until food has reached the lower intestine, fools the body into believing that it isn't hungry.

One type of capsule is described in Unilever's patent for a nutrition bar: "[the] polyunsaturated fatty acid or source thereof is encapsulating prior to inclusion in said bar by forming an emulsion of the unsaturated fatty acid with a carrier, spray-drying the emulsion to form a powder, and encapsulating said powder with an encapsulating agent."

All in the technique

Encapsulation not only protects the fat from oxidation, but is included so that certain metallic ions - often missing in the diet - can be added to the protein-rich bar without triggering oxidation of the fat component.

Another ingredient studied by food companies is resistant starch, which may be made from a variety of starches through chemical means or the use of high-amylose starch. Danone SA has introduced a nutrition bar that uses resistant starch as a means of engaging the ileal brake mechanism.

One such starch is described by National Starch Food Innovation in a February 2006 patent application: "The present invention relates to chemically modified starches, which, when properly formulated into foods or taken as a supplement, may be used to provide the consumer with more constant blood glucose (prevent/minimize acute elevation) levels over an extended time period (corresponding to the time the material is in the stomach/small intestine) than would be possible with other types of starches."

National Starch already is experiencing success with its Hi-maize resistant starch from corn, which can replace about 25 percent of flour in bakery formulations. Such starches and foods containing these starches will help consumers regulate and maintain normal and healthy blood glucose levels.

Another effect often associated with acute elevation and rapid swings in blood glucose levels is the inability to control and maintain body weight. Insulin, which plays many roles in the body, is active in the conversion of glucose to fats. Insulin resistance - the state of needing higher levels of serum insulin to metabolize the same level of glucose - is thought by some to be a cause, not an effect, of weight gain, as the increased insulin levels facilitate unnecessary fat storage.

Experts have long recommended eating multiple small meals over the course of a day to attempt to regulate blood glucose (and the corresponding energy supply) at a constant level. Additionally, rapidly falling blood glucose levels (which normally happen after an acute elevation) have been shown to trigger long-term stimulation of appetite in healthy adults.

Alternatively, research indicates glucose release over an extended time leads to benefits, which may include increased satiety for longer periods (valuable for weight management issues), sustained energy release for enhanced athletic performance and improved mental concentration and memory.

Multiple routes to success

As major companies have learned more about the mechanisms that produce a feeling of satiety, they've used different routes to reach the overall goal of getting a bigger piece of the diet food pie. With such a large number of people concerned about (or needing to be concerned about) overweight, the prize is to wrest food sales from mainstream products.

Unilever, after losing nearly half its Slim-Fast sales during the low-carb craze, developed a new Slim-Fast line. The new key, according to Terry Olson, general manager of marketing for Slim-Fast, is the product "convinces the body that it has consumed [the equivalent of] 500 calories," when it actually has consumed only about 190 in, for example, the Slim-Fast Shake. The new products appeared on shelves in January.

Kraft also has been looking to resistant starches. Todd Abraham, vice president of global research and technology strategy, was quoted earlier this year announcing "a new technology using resistant starches that act like fiber." He called the starch X150, for the 150th experiment that Kraft performed to find a good working starch that performs technically, but breaks down slowly during digestion.

In pursuit of the weight-loss magic bullet, Unilever is hedging its bets in another, far more audacious way. The company is looking seriously at hoodia, an African cactus that showed at least some promise in preliminary studies (see "Nutrition Beyond the Trends: Hoodia Love").

The hoodia component that is effective in killing appetite with no discernable side effects was patented by The Council for Scientific and Industrial Research in 1997 and subsequently licensed by Phytopharm. Unilever gained marketing rights, and is developing the compound with Phytopharm in an unusual (for Unilever) move. Products, according to company spokespersons, will appear in the marketplace next year.

What will provide the next big wave of diet products for people who need or desire to lose weight? Whether it's the Satiety Index, the low carbohydrate-based Glycemic Index or the fat-based ileal brake mechanism, the answer remains a scientific and marketing puzzle. But it's certain to be a puzzle with a big payoff.

About the Author

Frances Katz was vice president of research for American Maize Products, a past editor of Food Processing and was director of publications for the Institute of Food Technologists.