Understanding Hunger and Satiety Hunger - one of your body's strongest and most beneficial stimuli - helps insure that you consume enough Calories for your needs. However, it also works against you when you're trying to lose weight. You could easily lose weight just by eating less, but the less that you eat or the longer you postpone eating, the hungrier you become, and the longer it takes your hunger to subside once you do begin to eat. So the hungrier you are, the more likely it is that you'll overeat, consuming extra Calories that can quickly slow or reverse your weight loss. As you know, the only way to end hunger is to eat. Eating provides satiety - a pleasant feeling of fullness and the corresponding reduction of hunger. But did you also know that some foods are better than others for satisfying your hunger? A baked potato, for example, will probably "fill you up" much better than a serving of candy that has the same number of Calories. Experiments with Satiety

For years, researchers have studied satiety. While many things are known to influence satiety - including individual differences in endocrine levels from one person to another - one of the biggest factors is the type of food that you eat. Some foods fill your stomach faster and/or remain in your stomach longer, and therefor do a better job of holding off hunger. One of the most detailed studies that demonstrates this was conducted by Suzanna Holt and her fellow researchers at the University of Sydney. The results of their study, "The Satiety Index of Common Foods", were published in the European Journal of Clinical Nutrition, September 1995. In this study, the researchers fed human test subjects fixed-Calorie portions of thirty-eight different foods, and then recorded the subjects' perceived hunger following each feeding. The results of Holt's study, like many similar studies, indicate that satiety is most strongly related to the weight of the food consumed. In other words, the foods that weigh the most, satisfy our hunger best, regardless of the number of Calories they contain. However, higher amounts of certain nutrients, such as protein and dietary fiber, also appear to improve satiety. Can Satiety Be Predicted?

If there was a way of predicting satiety, we'd be able to select foods that satisfied our hunger, but contained fewer Calories. These foods would greatly improve our ability to create meals that were effective for weight loss. Because of the strong relation between satiety and a food's weight, some researchers have recommended the consumption of foods with low Caloric densities - i.e. foods that have the fewest total Calories per gram. One of the most notable of these researchers is nutritionist Barbara Rolls, Ph.D., whose prior best-selling diet book, Volumetrics, explained her use of low Caloric density foods for weight loss. A more recent diet that makes use of low Caloric density foods is the Negative Calorie Diet. There are also many specialty diets that use a low Caloric density approach. Included among these are the cabbage soup diet and the grapefruit diet. Unfortunately, Caloric density alone is not a reliable predictor of satiety, and it overlooks many enjoyable foods that would make wonderful additions to your diet. What you need is a better way to predict satiety.

The Fullness Factor - A Better Predictor of Satiety FF=MAX(0.5, MIN(5.0, 41.7/CAL^0.7 + 0.05*PR + 6.17E-4*DF^3 - 7.25E-6*TF^3 + 0.617)) where CAL is total Calories per 100g (30 minimum), PR is grams Protein per 100g (30 maximum), DF is grams Dietary Fiber per 100g (12 maximum), and TF is grams total Fat per 100g (50 maximum). After studying the results of numerous satiety studies, NutritionData used an advanced multivariate analysis of the existing data to create a new mathematical formula that predicts satiety from the nutrient content of a given food or recipe. This formula yields a value that we call the Fullness Factor (FF): FF values fall within the range of 0 to 5. Foods with high FF's are more likely to satisfy your hunger with fewer Calories. Foods with low FF's are less likely to satisfy your hunger. Comparing the Fullness Factor with Existing Satiety Data

After creating this formula, ND plotted its predicted values against the experimental data taken from Holt's 1995 study. Below is a graph that shows this comparison, and following the graph is some further discussion. Discussion

In the above graph, each blue bar represents the range of reported satiety values for each experimental food. (Approximately 12 human subjects participated in each food test, and results varied from one subject to another.) The black line represents the calculated Fullness Factors. As you can see, the Fullness Factor does a reasonably good job of predicting the satiety responses, with the possible exception of potatoes. Note, however, that the methodology of this particular study may have contributed to an artificially high satiety value for potatoes. Per the study's design, the participants were separately fed 220-Calorie servings of each food. A 220-Calorie serving of plain potatoes is larger and much less palatable than the other foods studied. The size of this serving may have influenced a repulsion to this test food that goes beyond the normal satiating response. In the above graph, each blue bar represents the range of reported satiety values for each experimental food. (Approximately 12 human subjects participated in each food test, and results varied from one subject to another.) The black line represents the calculated Fullness Factors. As you can see, the Fullness Factor does a reasonably good job of predicting the satiety responses, with the possible exception of potatoes. Note, however, that the methodology of this particular study may have contributed to an artificially high satiety value for potatoes. Per the study's design, the participants were separately fed 220-Calorie servings of each food. A 220-Calorie serving of plain potatoes is larger and much less palatable than the other foods studied. The size of this serving may have influenced a repulsion to this test food that goes beyond the normal satiating response. Note: As calculated, ND's Fullness Factor falls within the range of 0 to 5. For this comparison, the Fullness Factors were appropriately scaled (60X) to match the range reported in the study. Also, the foods names shown within the above chart are exactly as reported in the study, and do not necessarily match similar named foods from ND's database. To insure validity of this comparison, all nutrient values were taken directly from the study, which used foods primarily of Australian origin. Limitations of the Fullness Factor

The Fullness Factor is calculated from the food's nutrient content, using values from those nutrients that have been shown experimentally to have the greatest impact on satiety. There are, however, other things that can influence a food's ability to satisfy our hunger. In particular, a food's specific taste and texture - i.e. its palatability - can encourage or discourage consumption. Palatability of a food is a highly individual and subjective value, though, that can't be accurately measured. The Fullness Factor, by design, merely provides an estimate of food satiety prior to consumption. Benefits of the Fullness Factor

The benefits of the Fullness Factor far outweigh its limitations. The satiating effect of a food can now be more accurately predicted, solely from its nutrient content. This means that you can anticipate which foods and recipes will be most supportive of your diet. Values of the Fullness Factor range from 0 to 5, with the Fullness Factor for white bread being 1.8. That means that for servings of equal Calories, those foods with FF's above 1.8 are more likely to fill you up than white bread, and foods with FF's below 1.8 are less likely to fill you up than white bread.

Comparing the Fullness Factor with the Glycemic Index The Fullness Factor and the Glycemic Index are both nondimensional ratings which are used to predict your body's response to particular foods. While the Glycemic Index applies only to foods containing carbohydrates, the Fullness Factor can be used to evaluate all foods. A very detailed explanation of the Glycemic Index and Fullness Factor, as they relate to diet, can be found on ND's Glycemic Index page.

Fullness Factors for Common Foods Fullness Factors for Common Foods Food FF Bean sprouts 4.6 More filling

per Calorie Less filling

per Calorie Watermelon 4.5 Grapefruit 4.0 Carrots 3.8 Oranges 3.5 Fish, broiled 3.4 Chicken breast, roasted 3.3 Apples 3.3 Sirloin steak, broiled 3.2 Oatmeal 3.0 Popcorn 2.9 Baked potato 2.5 Lowfat yogurt 2.5 Banana 2.5 Macaroni and cheese 2.5 Brown rice 2.3 Spaghetti 2.2 White rice 2.1 Pizza 2.1 Peanuts 2.0 Ice cream 1.8 White bread 1.8 Raisins 1.6 Snickers Bar 1.5 Honey 1.4 Sugar (sucrose) 1.3 Glucose 1.3 Potato chips 1.2 Butter 0.5 The table below shows values of the Fullness Factor for a few common foods... General Observations

Foods that contain large amounts of fat, sugar, and/or starch have low Fullness Factors, and are much easier to overeat. Foods that contain large amounts of water, dietary fiber, and/or protein have the highest Fullness Factors. These high-FF foods, which include most vegetables, fruits, and lean meats, do a better job of satisfying your hunger. An Important Note

The above table just provides an example of the Fullness Factors for a few typical foods, and is not meant to be a complete food list. Use ND's search engine to find the foods that you currently eat and to determine their specific Fullness Factors. Similarly named foods can have much different FF's, depending on their ingredients. For example, plain popcorn (air-popped, without butter) has a higher FF than popcorn prepared with added butter. Fullness Factors for Liquids

Although all of the items in the above table are solid foods, the Fullness Factor can also be calculated for liquids, including soups and drinks. Most liquid foods will have above average Fullness Factors, due to their high water content. Liquid foods do, in fact, have a relatively high satiating effect, at least for the short term. However, low viscosity liquids (such as water, juice, or soft drinks) will empty from your stomach quickly, and may leave you hungry again in a relatively short time. Keep this in mind if you are using the Fullness Factor to select foods for weight loss.

Fullness Factors for Mixed Meals A Fullness Factor can be calculated for a mixed meal (i.e. the combination of several foods) in exactly the same way that it's calculated for an individual food. In fact, this is the most practical use of the Fullness Factor, since nearly everyone consumes multiple foods when they eat. And ND makes it especially easy to do this calculation. Simply "build" your meal as a recipe using the My Recipes feature in My ND. Click "Save and Analyze" to see the Fullness Factor™ for that meal. Note: To learn how to create recipes, please see the My Recipes Help page.

Fullness Factor Dieting The Fullness Factor can be used in conjunction with nearly any type of diet or approved food list. By simply selecting foods with higher Fullness Factors, you'll improve your chances of consuming fewer Calories, while simultaneously minimizing your hunger. For a diet that uses the Fullness Factor as its central concept, see our own Better Choices Diet and our special page on Dieting and Weight Loss.