Satiety Index

By Rick Mendosa and John Walsh, P.A., C.D.E.

How full did that meal you just ate make you feel? Did it satisfy your hunger, or did you need to snack later? Now, a new tool for measuring hunger and helping control blood sugar is available.

Studies by Australian researcher Dr. Susanne Holt at the University of Sydney have developed one of the most exciting diet concepts ever. Called the “Satiety Index,” it was developed by having students come in the morning and eat 240-calorie portions of a specific food. Then, they rated their feelings of hunger every 15 minutes, and over the next two hours, students could go to a buffet table and eat as much as they liked, all under the researchers’ observation.

Using white bread as the baseline of 100, they scored 38 foods given to the students. Foods above 100 were considered more satisfying than white bread, while those under 100 were less satisfying. Foods with a higher satiety index keep hunger down longer and would be better choices for those wanting to lose weight.

A fascinating finding of Dr. Holt’s study is that some foods, like croissants, are only half as satisfying as white bread, while potatoes are more than three times as satisfying. However, French fries did not score well! As a group, fruits ranked at the top for foods to choose from, with a satiety index 1.7 times higher than white bread.

Using this study, the May 1996 issue of  the “University of California-Berkeley Wellness Letter”  gave suggestions for weight-watchers trying to get the most satisfaction from the fewest calories:

• Potatoes gave the highest satisfaction, seven times higher than the least-filling croissants.
• Whole-grain breads are 50% more filling than white breads.
• Cakes, donuts, and cookies are among the least filling.
• For fruits, oranges and apples outscore bananas.
• Fish is more satisfying per calorie than lean beef or chicken.
• Popcorn is twice as filling as a candy bar or peanuts.

Holt’s Food Satiety Index

Holt’s Food Satiety Index is the first to demonstrate that foods with high-fat content create almost instant cravings for more of the same. Croissants, for instance, had the lowest score of all the foods tested, even though most people think of them as filling. Chips gave almost twice as much satisfaction as doughnuts, and popcorn scored higher than All-Bran. The best thing to eat is potatoes, which provide much more satisfaction than the same number of calories in white bread.

“Fatty foods are not satisfying, even though people expected them to be,” says Dr. 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 got enough fuel to be going on with.”

Overall, carbohydrates deter nibbling best, while protein-rich foods such as cheese, eggs, baked beans, meat, and fish come second and fruit third. However, there are big differences between the satisfaction value of foods within the same group.

“You can’t just say that vegetables are satisfying or those bakery products aren’t because there can be a two-fold difference between two similar foods,” says Dr. Holt.

“We found that bananas are much less satisfying than oranges or apples and that wholemeal bread is half as satisfying again as white bread. And a diet which simply recommends cereal for breakfast overlooks the fact that muesli is only half as satisfying as porridge.”

“One thing that I am concerned about is that many people do not know how to interpret these findings properly. The SI scores reflect the total amount of fullness produced by the set 1000 kJ portions of the test foods over 2 hours – i.e., short-term satiety. Although most foods with high SI scores kept fullness relatively high for the whole 2 hours, there were a few exceptions. The fruits were served in very large portions, but fullness dropped off quickly towards the end of the 2nd hour, reflecting the rapid rate of gastric emptying (oranges and apples and grapes are mainly sugar and water).”

“Many “health-conscious” dieters 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.”

One thing that makes a portion of food satisfying is its sheer bulk. ‘You can eat an awful lot of popcorn without taking in a lot of calories,’ says Dr. 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.’

Chemical constituents of foods also make a difference. ‘Beans and lentils, for example, contain anti-nutrients which delay their absorption, so they make you feel full for longer,’ says Dr. 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.’

Generally, the more satisfying a food felt, the more effective it proved as a nibbling deterrent. But even here, there were surprises. Volunteers fed jellybeans were unsatisfied, yet they ate very little afterward. This resulted in the sweets getting a satiety rating of 118 – higher than 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,’ said Dr. Holt. ‘We’ll be doing some research on that one – if we can persuade people to act as volunteers!”

Of all the food tests, boiled potatoes are easily the most satisfying. Since beans and lentils are slowly absorbed, they are among those foods that make you feel fuller longer.

Other factors may also be operative. Doug Skrecky thinks that one of these could be viscosity:

“I am currently analyzing the results of this index with respect to known determinants of satiety,” he writes me. “Preliminary findings indicate that in their explanations for the various SI ratings the authors have ignored at least one important factor which accounts for many of the otherwise unexplainable results: Viscosity effects. Dry foods, such as cookies, are more satiating than moist foods, like donuts. Foods with high moisture binding capabilities such as cheese, porridge, and potatoes can also increase the viscosity of stomach contents.”

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A recent message from Dr. Holt gave this advance information:

“I’ll let you know about any additional results we get. We’ve just done a short study comparing the satisfying power of different breakfasts. Two high-fat breakfasts of fried eggs and bacon and toast or croissants and jam were much less filling than two equal-calorie high-carb breakfasts which were either rapidly-digested (cornflakes with sugar and toast and jam) or slowly-digested (All-Bran with banana slices, toast, and marg).”

“I am also interested in how foods affect mood and alertness. The two high-carb breakfasts tended to improve alertness to a greater extent than the two high-fat breakfasts. Also, because the subjects were not completely satisfied with the two high-fat meals, they tended to be grumpy and a bit more aggressive/disappointed.

“I will be doing a satiety study with children soon.”

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Bibliography:

• Holt, S.H., Miller, J.C., Petocz, P., Farmakalidis, E. (Department of Biochemistry, University of Sydney, Australia.) “A satiety index of common foods.” European Journal of Clinical Nutrition, Volume 49, September 1995, pages 675-690.
• Holt, S.H., Brand-Miller, J.C., Petocz, P. (Department of Biochemistry, University of Sydney, NSW, Australia.) “Interrelationships among postprandial satiety, glucose and insulin responses and changes in subsequent food intake.” European Journal of Clinical Nutrition, Volume 50, December 1996, pages 788-797.

The Satiety Index Elsewhere on the Internet:

• “Diet Tips – The Satiety Index” reports on studies by researchers at the University of Sydney in Australia for National Bodybuilding & Fitness zine. The article says, “Food weight appears to be the determining factor. A portion that weighs more than another portion of the food of equal caloric value is more satisfying. For example, boiled potatoes rated very high on the index, foods like hard candy (high sugar foods), or candy bars rated very low. Extremely high-fat foods like cheesecake also rated badly, however some foods with moderate amounts of fat, such as lean steak, rate fairly well…A quick way to determine whether a food would have a high satiety index is to look it up in your calorie book and compare the calories to the portion size. If a 4-ounce food (about 120 g.) has over 250 calories – avoid it.”

• The Toronto Vegetarian Association says, “According to their investigation, the most satisfying foods were high in fiber. These included such items as whole grain products, potatoes, and fruits. Foods high in fat were the least filling. Ironically, the tastiest foods – those high in sugar and fat, like sweet bakery products – were the least satiating. Volunteers reached their caloric limit for these foods before they’d eaten enough to feel satisfied. In real life, there may not be a scientist looking over our shoulder to prevent us from going overboard on calories, so the tendency is to eat until satisfied and pay the price of being overweight.”

• An original report about the satiety index is “Carbohydrates in Human Nutrition; Interim Report of a Joint FAO/WHO Expert Consultation, Rome, Italy, 14 to 18 April 1997.” It says in part: “Two indices of carbohydrate foods based on their physiologic functions have been proposed. A recently suggested satiety index [citing reference 53, which is Holt, S.H.A., J.C. Brand-Miller, and P. Petocz. 1996. Interrelationships among postprandial satiety, glucose and insulin responses, and changes in subsequent food intake. Eur. J. Clin. Nutr.,50:788-797] measures the satiety value of equal energy portions of foods relative to a standard, which is white bread. The factors that control food intake are complex, and satiety needs to be distinguished from satiation. Nevertheless, investigation of satiety indices of foods is considered an interesting area of future research, which, if validated, may aid in selecting appropriate carbohydrate foods to promote energy balance. A more established index is the glycemic index, which can classify foods based on their blood glucose-raising potential.”

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© 1997, 2001 Rick Mendosa and John Walsh. All Rights Reserved.
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