The most filling foods, ranked by science

Two foods with identical calories can leave you completely differently. One keeps you full till your next meal; the other has you raiding the fridge in an hour. This isn't willpower. It's measurable, and in 1995 a group of Australian researchers measured it.

Susanna Holt and her team at the University of Sydney fed volunteers 240-calorie portions of 38 different foods, then tracked how full each one kept them over the next two hours and how much they ate afterwards. They scored every food against white bread, which they fixed at 100. Above 100 is more filling than white bread; below 100 is less.¹ The results are one of the most useful and least-known tools in fat loss.

The ranking

A selection from the study, plus the pattern it reveals. Higher is more filling per calorie.

The croissant, at 47, is seven times less filling than boiled potatoes at 323, for the exact same calories. That is the whole game of fat loss in one line.

What makes a food filling

The scores weren't random. Three things predicted a high score, and one predicted a low one:

• Protein filled people up and takes longest to digest.
• Fibre adds bulk with few calories and slows digestion.
• Water baked into the food (not drunk alongside) meant a bigger portion for the same calories.
• Fat did the opposite. Fat-heavy foods scored lowest, because fat packs the most calories into the smallest, least filling volume.

This is why the fat-rich bakery items sat at the bottom and the plain, whole, watery, protein-rich foods sat at the top. It also explains the odd results: whole oranges beat orange juice easily, because juicing strips the fibre and the chewing.

Why potatoes won

Plain boiled potatoes topped every food tested, which surprises people who've been told potatoes are fattening. They're not, in their plain form. They're mostly water and starch with almost no fat, so a filling portion is remarkably low in calories. Fry them into chips and the score collapses, because now they're a fat-delivery system. The potato didn't change; the cooking did.

How to actually use this

You don't need to memorise the table. You need the principle: build meals from high-satiety foods and you'll eat fewer calories without feeling like you're dieting. In practice:

• Lead every meal with a lean protein and a pile of vegetables or fruit.
• Choose the whole version over the processed one: potato over crisps, orange over juice, oats over a cereal bar.
• Treat the low-satiety foods, the pastries, chips and ice cream, as things you enjoy occasionally with your eyes open, not as staples. They give you the fewest full minutes per calorie of anything you can eat.

Satiety versus calorie density

There's a close cousin to the satiety index worth knowing: calorie density, the calories packed into a given weight of food. The two explain the same thing from different angles. Low-calorie-density foods, vegetables, fruit, potatoes, broth-based soups, let you eat a large, satisfying volume for few calories, which is exactly why they scored high on Holt's index. High-density foods, oils, nuts, chocolate, pastries, pack many calories into a small bite that's gone in seconds, so they leave you wanting more. When you fill most of your plate with high-volume, high-satiety foods and treat calorie-dense foods as accents rather than the main event, portion control stops feeling like restraint and starts happening on its own.

A quick self-test

Not sure where a food sits? Ask three questions. Does it have protein or fibre? Is it mostly water, or dry and dense? Does it need chewing, or does it slip down fast? A food that's protein-rich, watery and needs work to eat, a bowl of dal, a boiled egg, an apple, will fill you up. One that's dry, fatty and effortless, a biscuit, a handful of crisps, will not. You can rank almost any food in your head this way without a table.

One caveat the researchers themselves raised: filling isn't the same as healthy. You could eat nothing but potatoes and feel stuffed on few calories, but you'd be missing most of what your body needs. Use satiety to guide portions and choices, inside a varied diet, not as the only rule. Paired with a sensible calorie target, it's the difference between a diet that fights you and one that quietly works.