Why Am I Still Hungry After a Packet of Chips? A Singapore Guide to Snack Satiety

You open a packet of chips at 3.30pm, tell yourself you will have a few, and twenty minutes later the packet is empty and you are opening the pantry cupboard again. Meanwhile a colleague eats a hard-boiled egg and does not think about food until dinner.

Same afternoon, roughly similar calories, completely different outcome. This is not a willpower problem. It is a well-studied phenomenon called satiety, and the food itself is doing most of the work.

Calories tell you almost nothing about how full you will feel

The most useful study on this is still one of the oldest. In 1995, researchers at the University of Sydney published A Satiety Index of Common Foods in the European Journal of Clinical Nutrition. They fed volunteers identical 240-calorie (1000 kJ) portions of 38 different foods, asked them to rate their fullness every 15 minutes for two hours, and then let them eat freely to see how much they actually consumed afterwards.

Every portion had the same energy. The fullness results did not come close to matching.

Using white bread as the benchmark of 100, boiled potatoes scored 323 — the most filling food tested. A croissant scored 47, seven times lower. Within the snack aisle the spread was just as revealing: crisps scored 91, peanuts 84, a chocolate bar 70, while popcorn hit 154 and plain crackers came in at 127.

Read that again. Crackers outscored crisps by a wide margin, on identical calories.

What actually drives the difference

The Sydney team ran the correlations, and they are worth knowing because they are the closest thing we have to a shopping rule.

  • Water content correlated most strongly with fullness (r = 0.64)
  • Fibre came next (r = 0.46)
  • Protein also helped (r = 0.37)
  • Fat worked in the opposite direction (r = −0.43) — more fat, less fullness per calorie

Serving weight mattered enormously too (r = 0.66). Heavier, bulkier portions filled people up more, largely independent of the calories in them. Your stomach has stretch receptors; they respond to volume, not to the energy number on the packet.

This explains the chips problem neatly. A crisp is mostly starch and fat, contains almost no water, and weighs very little for the calories it delivers. Thirty grams of it barely registers as bulk. It ticks every box the research associates with poor satiety.

There is one honest wrinkle in the data: the researchers also found that the more palatable a food was rated, the lower its satiety score tended to be (r = −0.64). Snacks engineered to taste irresistible are, almost by design, snacks that are easy to keep eating.

Does texture matter, or is that just marketing?

Snack brands love to claim that a satisfying crunch helps you stop eating. The evidence is real but softer than the marketing suggests. A 2020 systematic review and meta-analysis in Scientific Reports pooled the trials on food texture and satiety and found that solid foods reduced hunger more than liquid ones, and that thicker, more viscous foods increased fullness ratings.

The effects were measurable but modest, and the authors were explicit that the variation between studies was large enough that the results should be interpreted cautiously. Texture is a real lever. It is not a bigger lever than protein, fibre and portion weight.

Turning this into something you can use in NTUC

The Health Promotion Board's guidance on healthy snacking uses a simple rule of thumb: keep snacks under 200 Calories, and look for nutrient density rather than just a low number. Their worked examples are useful reference points — four rice crackers come in around 55 Calories, 20g of unsalted popcorn around 75, and a packet of chips carrying the Healthier Choice Symbol under 100.

Combining HPB's advice with the satiety research gives you three things to check on the back of the packet:

  1. Protein per 100g. Most crisps and crackers land between 5g and 8g. Anything meaningfully above that is doing something different.
  2. Dietary fibre per 100g. Often the single biggest gap between two snacks that look identical from the front of the pack. Wholegrain versions usually win here.
  3. Total fat per 100g. Not because fat is bad, but because in this specific context it buys you calories without buying you fullness.

And check the serving size line while you are there. A snack that looks moderate at 30g is a different proposition if the packet contains 90g and you are unlikely to stop halfway.

The caveats worth keeping

The satiety index study used 11 to 13 people per food, which is small. It measured single foods eaten alone, not the mixed snacking most of us actually do. And it says nothing about nutritional quality — jellybeans scored 118, comfortably above white bread, partly because they made some participants feel a bit queasy.

Satiety is one input among several. It is not a ranking of which foods are good for you. But it does explain something most calorie counting misses: two snacks with the same number on the label can leave you in completely different places an hour later.

Where our crackers fit

We built HexaCrunch around exactly this problem. Our crackers are baked, not fried, made on a wholegrain brown rice base, and we add cricket protein to lift the protein and fibre lines rather than the fat line — because those are the numbers the research keeps pointing at.

We would rather you checked our label against the three checks above than took our word for it. If you want to taste-test the idea, the Try-All 3-Pack lets you try all three flavours before committing to a favourite.

Sources

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