Abundant research is being done on the factor of satiety: which foods trigger it, which foods keep that satisfying feeling longest and best, and how flavor and aroma affect satiety, both positively and negatively.
Of the many reasons people seek to lose weight, the medical reason has the biggest impact on subsequent food choices. While fat may be satiating, for those with a genetic predisposition, dietary fat can have a sizeable effect on blood cholesterol levels.
In June 2004, a review of the literature on satiety and its causes was published in the American Journal of Clinical Nutrition (www.ajcn.org). The article identified a number of biomarkers - mostly peptides and hormones - which turn the urge to eat on and off. The researchers from Utrecht University and TNO Nutrition and Food Research, at Wageningen University in the Netherlands, noted there are also physiological factors, including time of day, family influences and others.
|Barley is beginning to appear as a side dish replacing rice - it has more fiber, is lower on the glycemic index and higher on the satiety index. Photo courtesy of ConAgra.
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).
Note to Marketing
It may be a little ahead of the curve, but consumers are beginning to catch on to the Satiety Index. It's a concept that's perhaps worth explaining to your customers, especially if it makes your product look good.
However, be careful with labeling. Fiber claims have been approved, and may be appropriate for some products. But marketing departments should talk to the FDA about what is acceptable before committing any verbiage about the Satiety Index to a label.
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.