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2005/08/12, 08:03 PM
Just something I found that I thought would be very helpful.
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. Susanna 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.
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, 38 different foods were ranked. 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 is one of the factors that determines 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."
It is, in fact, the size, bulk and blandness of potatoes that may account for much of its high satiety. Their "portion weight was up to four times greater than the other foods ," Holt and her co-authors note in a paper published in the December 1996 issue of the European Journal of Clinical Nutrition.
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 ."
This too can be valuable information to the weight conscious. "A diet which simply recommends cereal for breakfast overlooks the fact that muesli is only half as satisfying as porridge ," she adds.
Some Surprises
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!"
A Few Words of Advice
Holt is concerned that there may be some confusion in the interpretation of her study's findings. "The Satiety Index scores reflect the total amount of fullness produced by the set portions of the test foods over two hours—i.e. short-term satiety. Although most foods with high Satiety Index scores kept fullness relatively high for the whole two hours, there were a few exceptions," Holt notes.
"The fruits were served in very large portions, but fullness dropped off quickly towards the end of the second hour, reflecting the rapid rate of gastric emptying (oranges and apples and grapes are mainly sugar and water)," she adds.
"Many 'health-conscious' dieters," she continues, "will eat a meal based on several pieces of fruit and some rice cakes (in Australia anyway) and then wonder why they feel ravenous a few hours later. These kinds of extremely low-fat, high-carb meals do not keep hunger at bay because they are not based on slowly-digested carbs and probably don't contain enough protein. A dieter would be better off eating a wholesome salad sandwich on wholegrain bread with some lean protein like tuna or beef and an apple. This kind of meal can keep hunger at bay for a very long time."
Update
NutritionData.com has just published on that site a self-directed diet that uses what it calls the "Fullness Factor" at http://www.nutritiondata.com/fullness-factor.html.
Ron Johnson, who together with his wife, Lori, developed NutritionData.com, explains the Fullness Factor concept in email to me, part of which I except below because it clarifies what they publish on the website:
Sue Holt's study played an important role in the Fullness Factor concept, because it's the only published study (to our knowledge) that provides quantitative observations of satiety along with nutrient composition for a reasonably wide variety of foods. Modeling this data set alone, however, proved to be problematic, as it is still limited in number and doesn't represent the full range of foods that humans consume. We consulted many other studies and published observations (such as Barbara Rolls's Volumetrics) to help establish additional data points or constraints, which were then used to create the current FF formula.
There are at least three criticisms of the Fullness Factor that we readily acknowledge:
* The formula doesn't take into account all known contributing factors for satiety.
* The formula is derived from a small data set.
* The data set is based on subjectively reported, rather than directly measured, criteria.
The Fullness Factor is our first pass in establishing the concept that the satiating effect of a food can be reasonably well predicted from commonly available nutrient values. We have not published a book or tried to sell this concept. We are merely giving our web visitors free access to FF calculating tools to allow their own experimentation. Our site sees approximately 500,000 visitors per month, which undoubtedly includes some obesity researchers. Hopefully the presentation of our ideas will encourage additional studies that will allow this concept and formula to be further improved.
I have a great deal of respect for the amount of GI research that Jennie Brand-Miller has done. I believe that GI and GL are invaluable markers for carbohydrate evaluation. As a scientist and athlete, I've used GI values to help guide my own dietary decisions for more than 10 years. However, the general public (or at least the general American public) has tried to take GI beyond its original premise. In our opinion, it's not a complete enough indicator to be the entire basis for a diet. Of course, neither is/was the whole “low carb” idea.
Our goal is to create or help create a simpler way for the average person (who may not even understand what a carbohydrate is) to evaluate foods. FF is not the complete answer, but we believe it's at least an improvement over simple caloric density. And when we combine FF with our nutrient-density-based Rating, as we do on our Nutritional Target Map (described on http://www.nutritiondata.com/better-choices-diet.html), the resulting food recommendations fall fairly well in line with most respected dietary plans (i.e., higher reliance on fresh fruits, vegetables, fish, and lean meats; lower reliance on sugars, fats, and processed foods). Our calculations may never replace a knowledgeable dietician, but we hope they help bridge the gap for those without access to that knowledge and assistance.
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The best feeling in the world is the feeling you get after a tough set of squats after you step back from the power rack and throw up all over the floor.
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