You know the feeling. You've eaten most of a large bag of something, you're vaguely aware you've had a meal's worth of calories, and you're standing at the fridge ten minutes later wondering what else there is.
It isn't willpower. There are decades of research looking into the physical characteristics of food and how they can influence perceived fullness, although the evidence is much messier than a single score makes it look.
The study everyone quotes
In 1995, a team at the University of Sydney tried to measure it properly. They gave volunteers 240-calorie portions of 38 different foods — identical calories, wildly different foods — then asked them to rate their fullness every fifteen minutes for two hours, and measured how much they ate afterwards.
White bread was set at 100. Everything else scored relative to that.
Boiled potatoes came top at 323 — over three times as filling as white bread, calorie for calorie. Croissants came last at 47.
And crisps scored 91. Below plain white bread.
That's the whole problem in one number. A snack that most people would describe as satisfying registered as less filling than a slice of bread with nothing on it.
What actually predicted fullness
This is the interesting part, and it isn't what you'd guess.
The strongest predictor wasn't protein. It was how much the food physically weighed. A 240-calorie serving of potatoes is a substantial pile; 240 calories of croissant is not much croissant. Your stomach responds to volume, and calories are invisible to it.
Water content came next, for the same reason — it adds weight without adding energy.
Fibre mattered. Protein mattered, though less than the headlines usually suggest. Fat was negatively associated — fattier foods were less filling per calorie, not more.
And then the finding nobody enjoys: the tastier a food was rated, the less filling it was. Palatability was inversely correlated with fullness, and strongly so.
Why that combination describes most snack food
Look at what a crisp is. It's low in weight — a bag of air and thin slices. It's had the water driven out of it, which is what makes it crisp. It's high in fat, because it's been fried. And it's engineered to be extremely palatable, because that's the entire commercial proposition.
Every one of those is on the wrong side of the ledger. It isn't that crisps are badly made. They're superbly made, for a purpose that has nothing to do with leaving you full.
The same logic explains the croissant at the bottom of the list, and it explains why a boiled potato — heavy, wet, bland — sits at the top. Blandness is not a flaw in a food you want to fill you up. It's part of the mechanism.
What this means if you're just trying to get to dinner
Not a diet plan. Just the practical version:
Weight and water do more than you'd think. A snack with some substance to it registers in a way an airy one doesn't.
Fibre and protein help. Baked beans scored 168, eggs 150, lentils 133. Whole pulses tend to do well on both counts, largely because nothing has been strained out of them. Nuts, notably, did not — peanuts came in at 84, below white bread, because they're dense in calories and light in weight.
Fried and dry is the difficult combination. Frying removes water and adds fat — the two things the data liked least.
If you're hungry, eat something. The point of this research isn't to eat less. It's that some foods answer the question and some don't, and it's useful to know which is which before you've eaten your way through a family bag looking for an answer that was never in there.
The caveats, because they matter
This was 38 foods, eleven to thirteen people per food, thirty years ago. Three decades on, no comparable index has replaced it — which says as much about how difficult satiety is to measure as it does about the study.
The measurement itself has been criticised. Researchers at the US Army's Natick centre, developing their own satiety scale for ration design, pointed out that Holt's rating scale used verbal labels — "semi-hungry", "satisfied", "extremely full" — that differ in kind rather than merely in degree, with no evidence they sit at equal intervals. They also noted that "satisfied" quietly imports a judgement about enjoyment into what is meant to measure fullness alone. Fair criticism, and worth knowing.
The potato result in particular has been questioned. A 240-calorie serving of plain boiled potato is a large and fairly joyless amount of potato, and at least one analysis has suggested the sheer volume and blandness may have produced something closer to reluctance than to genuine fullness. The score is real; whether it means quite what it appears to is less certain.
The individual scores are best read as a rough ranking rather than precise measurements — and the food-by-food figures come from the table reproduced from the study rather than the published abstract, which reports only the highest and lowest.
What has held up is the pattern. A 2016 trial in Toronto found children ate 30–40% fewer calories at meals served with boiled and mashed potato than with rice, pasta or chips — a completely different design arriving at the same place. Weight, water and fibre help. Fat and sheer palatability don't.
Where we come into it
We started making a snack because we were tired of how much of the aisle is built around the same formula: something very light, something fried or puffed, and a seasoning doing most of the work.
TEMPTÉ starts somewhere else. The main ingredient is tempeh, made from whole fermented beans, and we’re baking rather than frying it. The result we’re working towards is deliberately firm and substantial rather than light and airy.
None of that means a snack can make decisions about hunger for you. But it does mean the physical structure is quite different from the puffed things at the other end of the aisle, which is partly why we found the research above interesting in the first place.
Keep reading
- What Is Tempeh? A Simple Guide to Our Hero Ingredient
- Tempeh vs Tofu: What’s the Difference?
- Why We Make Snacks From Tempeh
- What Does Fermentation Actually Do to Tempeh?
- Tempeh, Miso, Natto and Koji: What's the Difference?
From tempeh to your snacking plate. Meet TEMPTÉ →
Sources
- Satiety Index methodology, scores and correlations: Holt SHA, Brand Miller JC, Petocz P, Farmakalidis E. "A satiety index of common foods." European Journal of Clinical Nutrition, 1995;49(9):675–690
- Follow-up work on potato satiety in mixed meals: Akilen et al., Nutrition & Diabetes, 2016
- Critique of the Holt rating scale: Cardello et al., development of a labeled magnitude scale of perceived satiety, Appetite and The development of a perceived satiety index for military rations, Food Quality and Preference
General information about food science, not dietary advice.