The number of different foods available to American consumers has exploded by over 4000 percent over the last 65 years, and many experts link this increase in variety with an upsurge in average body weight. although some research suggests that variety is not responsible for weight gain, a new investigation reveals that increases in variety of certain foods and decreases in variety of other edibles are associated with weight loss over the long term.

In 1938, average American grocery store stocked 800 items.

By 1983, that number had grown to 10,000 products, and today the figure is close to 35,000 (1). This is of course a wonderful development for consumers who enjoy having access to a potpourri of products, but there is one potential problem: Some experts contend that the tremendous variety of foods available today is making us fat.

At first glance, of course, the nation seems somewhat absurd. Why would the mere presence of a salmagundi of sustenance pack blubber under our skins? In fact, eating a variety of comestibles should make dining more interesting and satisfying and thus decreased the need to fill our bellies to the top in order to feel satisfied.

However, the notion that diversity in food items leads to corpulence is based on sound scientific reasoning and research. The physiological mechanism involved is something called sensory-specific satiety (SSS).

Here's how SSS works: As you eat a bowl of lentils (or rather, the lentils inside the bowl), your nervous system gradually gets used to the sensory qualities of the starchy little pellets. The first bite tastes great (provided you have seasoned the dish properly), the second mouthful not as great but still good, the third chomp less-flavorful still, and so on. Before too long, your sensory system totally loses interest in the lentils, and you tend to stop eating when your tummy feels moderately full or your hunger oangs are alleviated. If the lentils are the only item on your menu, you do not overeat. You become satiated in part because of the sensory-specific qualities of lentils, which are simply not "interesting" enough to keep your jaws moving for long. This is SSS in action.

Put a plate of General-Tso's chicken on the table along with the lentils, however, and everything changes. Tso's chicken creates novel sensations in your nose and mouth which arouse your brain and stimulate eating, and your total intake of food is greater, compared with a one-item meal. Add a platter of Chinese spare ribs to the equation (or Southern ribs, for that matter: the geographic designation has no bearing on SSS), and ingested calories continue to climb.

This effect of the hedonic qualities of foods can make a difference during one meal and over longer periods of time, as well. If you are eating beans and rice for nearly every meal, for example, your meal size will gradually get smaller over the course of several weeks (and may become vanishingly small as your taste for rice and beans turns completely sour). In contrast, if you are constantly sampling a rich array of foods, meal size will tend to be much-more robust. The presence of a variety of foods can lead to overeating; some research suggests that variety can hike daily caloric consumption by as much as 25 percent (1).

Food marketers are well aware of the pernicious effect that SSS can have on sales of their products. That's why Coca-Cola has more than 400 different kinds of drinks (1). If you are tired of Coke there is a problem - there are 399 calorie-rich Coca-Cola made quaffables to lure you away from plain water. Thanks to SSS, Frito-Lays puts close to 150 different chips and pretzels on grocery shelves around the world, and Campbell's offers 10 soups (ibid), just in case you get a bit tired of chicken-noodle pottage. In many grocery stores, breakfast cereals have their own specil aisle, a special tribute to the physiology of SSS.

True, not everyone believes that greater dietary variety can increase the risk of being overweight. Professor  Richard Mattes of Purdue University agrees that variety prompts people to eat more, but he suggests that people compensate for the extra eating at subsequent meals, eating less than they usually would and "balancing out" their daily and/or weekly caloric intakes (1). However, research carried out with laboratory animals paint a rather grim picture of dietary variety and energy intake; these studies reveal that when animals are offered a greater collection of foods, especially when the comestibles are energy-dense, the little beasties take in more energy, gain additional weight, and become fatter, compared with the provisioning of a small sample of different foodstuffs (2). Likewise, human studies suggest that individuals who have greater dietary variety tend to eat more calories per day and pack more fat into their subcutaneous and deep tissue spaces (3, 4, & 5).

So, can decreasing your food variety help you lose weight - without hurting your health (after all, variety can be a good thing, since it can broaden the spread of different nutrients which you ingest and thus decrease the risk of a vitamin or mineral deficiency)? To find out, H.A. Raynor, Rena R. WIng, and their colleagues from Brown Medical School/Miriam Hospital in Providence, Rhode Island (USA) and the School of Public Health at the University of Minnesota recently studied 121 overweight adults for a total of 18 months (6). The subjects were 25 to 50 years of age and were 14 to 32 kilograms overweight; the average BMI was 32.3 kg/m2/

The participants in the study attended weekly group meetings for six months, biweekly meetings from the seventh to 12th month of the investigation, and monthly get-togethers from month 13 through 18; during these assemblies, the subjects received instruction on the topic of diet, physical activity, appetite control, problem-solving, goal setting, social support, motivation, and relapse prevention. The individuals were divided into two groups, with the members of one group burning about 1000 caloies per week during exercise (consisting of approximately 30 minutes of medium-intensity walking per day) and individuals in the other group expending about 2500 weekly calories via exertion (with close to 75 minutes of walking each day). The basic dietary goals  were the same in the two groups: all subjects reduced daily caloric intakes to 1000 to 1500 calories and derived 20 percent of total energy from fat.

To learn more about SSS and Your Weight (the full article can be read by purchasing Vol.1 Issue 5) and many more weight-loss related topics. Simply click on Back Issues, then select Vol. 1 Issue 5 from the drop-down menu. Or enter any subject you wish to learn more about. A subscription to Weight-Loss Research News is another way to receive valuable information. BUY NOW.

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