5 foods under 20 calories per 100 g
This is the first band that grows out of the ground, and it is almost entirely salad. Half a kilo of anything on this list is 70 to 85 kcal — a mound of food for less than a slice of bread.
| Food | kcal per 100 g |
|---|---|
| Iceberg lettuce | ~14 |
| Celery | ~14 |
| Cucumber, with skin | ~15 |
| Radishes | ~16 |
| Courgette (zucchini) | ~17 |
Just behind them, all within a kilocalorie or two of the cut: pak choi (13), chard (19), romaine (17), endive (17), tomato (18), daikon (18) and sauerkraut (19).
The arithmetic that makes the band useful
Appetite tracks the weight and bulk of food at least as much as its energy. People eating freely tend to settle on a fairly consistent mass per day, which is the whole mechanism behind high-volume eating.
At 15 kcal per 100 g, mass is free. A 400 g plate — a genuinely large pile — is about 60 kcal. The same 400 g drawn from the top of the density ladder is 1,600.
Swap, do not add
This is the part most “eat more salad” advice gets backwards. Adding 200 g of cucumber to a meal saves nothing; it adds 30 kcal. Replacing something with it is where the saving lives:
| Swap | Change |
|---|---|
| 100 g cooked rice → 100 g courgette ribbons | −113 kcal |
| 100 g pasta → 100 g spiralised courgette | −140 kcal |
| Half a sandwich → 150 g celery and radish | −150 to −200 kcal |
| Crisps alongside lunch → 200 g cucumber sticks | −230 kcal |
Used as the bulk half of a plate, this band lets you cut a meal’s calories without cutting its size. Used as an extra, it is just extra.
The dressing is bigger than the salad
A 400 g salad from this list is about 60 kcal. Two tablespoons of an olive-oil dressing is 160 to 240. The dressing is three or four times the food it is dressing, and it is the single most common reason a “salad for lunch” lands at 600 kcal.
- 1 tbsp olive oil: ~120 kcal
- 2 tbsp mayonnaise-based dressing: 100–180 kcal
- 50 g crumbled feta or cheese: 130–165 kcal
- A handful of croutons: 80–120 kcal
- 30 g almonds scattered over: ~175 kcal
None of those is a bad thing to eat. But they are the meal, and the leaves are the garnish — which is the reverse of how the plate looks.
What this band cannot do
Two honest limits, and they are the same two for everything on the list.
There is nothing in it. Per 100 g these carry 0.7 to 1.3 g of protein and 0.5 to 1.1 g of fibre. A whole cucumber is 1.4 g of protein. They belong next to something protein-dense, not in place of it.
Water-based fullness empties fast. Usually within an hour or two, because there is no fat, little fibre and no protein to slow gastric emptying. These foods delay appetite rather than settling it. A bowl of spinach at 23 kcal or cabbage at 25 — the next band up — holds you a little longer for a difference you will never notice on a tracker.
A note on preparation
Courgette and radish change character with heat and are worth cooking; cucumber and lettuce do not survive it. Courgette releases a lot of water in the pan, so salting and draining it for twenty minutes first is the difference between ribbons and soup. Radishes roast sweet and lose their bite entirely.
And watch what the heat arrives in. Courgette is a sponge: 100 g sautéed in a poured tablespoon of oil is 17 kcal of vegetable carrying 120 kcal of fat. The same dish with a sprayed teaspoon is about 55 kcal in total. The vegetable is never the variable.
The rest of the ladder
Under 5 · under 10 · under 20 · under 30 · under 50 · under 100 · under 200 · under 300 · under 400 · under 500
Figures are typical values from USDA FoodData Central and product labels, and vary by variety, size and preparation. General information, not medical advice.