How full did that meal you just ate make you feel? Did it satisfy your hunger, or did it make you feel like you'll need a snack later?
Now a new tool is available to measure the hunger fighting power of certain foods and help with blood sugar control. Studies by Australian researcher Dr. Susanne Holt and her associates at the University of Sydney have developed one of the most exciting diet concepts ever. Called, the "Satiety Index," Holt's tool ranks different foods on their ability to satisfy hunger.
Fatty foods are not satisfying.
Holt drew up the Satiety Index by feeding 240-calorie portions of 38 different foods to volunteers. The foods were served from under a hood to minimize the influence of appearance, and, if possible, they were served at the same temperature and in the same size chunks.
After eating, the volunteers told the scientists what their appetite ratings were, but they were not allowed anything else for the next two hours. Then, after two hours, they were then allowed to eat from a small buffet, where the scientists measured how much they nibbled from a variety of other foods. Their consumption was closely monitored, and every 15 minutes they were questioned about their hunger to see if their subjective impression of satisfaction matched their eating behavior.
Using white bread as the baseline of 100, they ranked 38 different foods. In other words, foods scoring higher than 100 are more satisfying than white bread and those under 100 are less satisfying.
What Really Satisfies?
Holt found that some foods, like croissants, are only half as satisfying as white bread, while boiled potatoes are more than three times as satisfying, easily the most satisfying food tested. But potatoes in a different form—French fries—did not score well. This type of information can have important implications for those wanting to lose weight.
The chemical components of a food help determine how it ranks on the index. "Beans and lentils, for example, contain anti-nutrients which delay their absorption so they make you feel full for longer," says Holt. "Roughly speaking, the more fiber, protein and water a food contains, the longer it will satisfy. But you have to look at each foodstuff individually—and that is why we think our index will be so useful."
Another thing that makes a food satisfying is its sheer bulk. "You can eat an awful lot of popcorn without taking in a lot of calories," says Holt. "It may not weigh much, but it makes your stomach feel full just because it takes up so much space. Oranges come out very high on the index for the same reason—but orange juice probably wouldn't, even though it has the same number of calories."
As a group, fruits ranked at the top with a satiety index 1.7 times more satisfying, on average, than white bread. Carbohydrate-rich foods and protein-rich foods deter nibbling almost as well. Holt warns, however, that there are big differences between the satisfaction values of individual foods within the same group.
"You can't just say that vegetables are satisfying or that bakery products aren't, because there can be a two-fold difference between two similar foods," says Holt. "We found that bananas are much less satisfying than oranges or apples, and that wholemeal bread is half again as satisfying as white bread [157 compared to 100 respectively]." This too can be valuable information to the weight conscious. "A diet that simply recommends cereal for breakfast overlooks the fact that muesli is only half as satisfying as porridge [oatmeal]," she adds.
In general, the more satisfying a food felt, the more effective it proved as a nibbling deterrent. But even here there were some surprises. "Fatty foods are not satisfying, even though people expected them to be," says Holt. "We think the reason is that fat is seen by the body as a fuel which should be used only in emergencies—it stores it in the cells instead of breaking it down for immediate use. Because it doesn't recognize the fat as energy for immediate use, the body does not tell the brain to cut hunger signals, so we go on wanting more. Carbohydrates are the opposite—they raise blood glucose so the body knows it has gotten enough fuel."
Jellybeans also scored higher than expected. Volunteers fed jellybeans did not feel satisfied, yet they ate very little afterwards. This resulted in the sweets getting a satiety rating of 118—higher than that of muesli and yogurt and almost the same as white pasta.
"I suspect the reason that the jellybeans came out so well was that they made our volunteers feel slightly nauseous," says Holt. "We'll be doing some research on that one—if we can persuade people to act as volunteers!"
This article originally appeared on the Diabetes Digest site, April 1999.
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