The Satiety index
Understanding why some foods keep you full longer than others has been a central question in nutrition science—and the answer is more complex than calories alone. In 1995, researchers introduced the Satiety Index (SI) to measure how different foods impact fullness over time, revealing surprising differences even among foods with the same calorie content. This landmark study challenged the common assumption that glycemic index (GI) is the primary driver of satiety, and instead highlighted the powerful role of factors like protein, fiber, water content, and energy density. In this post, we’ll break down what the Satiety Index is, what the research uncovered, and how these insights continue to shape modern approaches to appetite regulation and weight management.
The study measured satiety produced by 38 foods, each providing 1000 kJ (~240 kcal), and compared hunger ratings over 2 hours. White bread was used as the reference food (SI = 100).
1. Food Satiety Index
Satiety Index Rankings (Selected Foods)
Boiled potatoes 323
Ling fish 225
Porridge (oatmeal) 209
Oranges 202
Apples 197
Brown pasta 188
Beef 176
Food Satiety Index
Beef 176
Baked beans 168
Grapes 162
Whole-grain bread 157
Popcorn 154
Eggs 150
Cheese 146
White rice 138
Lentils 133
French fries 116
White bread (reference) 100
Cornflakes 118
Doughnuts 68
Croissants 47
2. Relationship Between GI and Satiety in the Study
The researchers expected low-GI foods to produce greater satiety, but the results showed the relationship was weak.
Important observations: High satiety foods often had characteristics such as:
high fiber
high water content
high protein
low energy density
Examples:
potatoes
fish
oatmeal
fruit
High GI but high satiety
Some foods contradict the GI–satiety assumption. Example: Potatoes have a high GI and high satiety.
Reason:
high water volume
low energy density
large gastric distension
Low satiety foods
Foods with low satiety index tend to be:
high fat
energy dense
highly processed
Examples:
croissants
doughnuts
cake
These may have moderate GI but still low satiety.
3. Key Conclusions of the Study
The authors concluded:
1. Satiety differs greatly between foods with the same calorie content.
2. Energy density is a major predictor of satiety.
3. Protein and fiber increase satiety.
4. GI alone cannot predict satiety reliably.
4. Modern Understanding (Satiety Determinants)
Today, satiety is understood to depend on multiple interacting variables:
Factor Effect
Protein strong satiety effect
Fiber slows digestion
Water content increases stomach volume
Energy density lower density → higher satiety
Food structure whole foods digest slower
Glycemic response influences metabolic hunger signals
Thus:
Satiety = f (GI only)
Instead:
Satiety = f (GI, fiber, protein, water, energy density, food structure)
✅ Key Insight
The Holt study revealed a critical point in nutrition science:
Foods with identical calories can differ three- to six-fold in their satiety effect. This finding strongly influenced modern research on appetite regulation and obesity prevention
Research Confirming These Findings
Subsequent studies expanded on Holtʼs findings.
1️⃣ Ludwig (2002)
Journal of the American Medical Association Proposed the carbohydrate–insulin model, suggesting:
high-GI foods → rapid glucose decline → hunger
2️⃣ Bornet et al. (2007)
Appetite
Review of 32 studies. Findings:
low-GI foods often increase satiety
effects are not universal
3️⃣ Aston et al. (2008)
Obesity Reviews Conclusion:
GI contributes to satiety but food composition is more important.
4️⃣ Rouhani et al. (2017)
Nutrition Journal Systematic review. Result:
low-GI diets slightly increase fullness
effect on hunger and calorie intake is modest