5 foods under 100 calories per 100 g
This is the first band you could actually live on. Two thousand kilocalories at 80 kcal per 100 g is 2.5 kg of food a day — heavy, but a real person’s intake once some denser food is mixed in. Everything below this rung was a side dish pretending to be a meal.
It is also where protein arrives properly.
| Food | kcal per 100 g | Protein | Protein per 100 kcal |
|---|---|---|---|
| Raw egg white | ~52 | 10.9 g | 21 g |
| 0% Greek yoghurt | ~59 | 10.3 g | 17 g |
| Cottage cheese, 1% | ~72 | 12.4 g | 17 g |
| White fish (cod, haddock, pollock), raw | ~75–85 | 17–18 g | 22 g |
| Boiled potato | ~87 | 2.0 g | 2 g |
Also on this rung: raw prawns (85), silken tofu (55), boiled sweet potato (76), porridge made with water (71), mango (60), grapes (69) and a banana (89).
Why the last column is the one to read
Protein per 100 kcal is the figure that decides whether a food helps in a deficit, and nothing in the four bands below gets close to this one. Broccoli — the best of the cheap bands — manages 8 g per 100 kcal. Cod manages 22.
That matters because protein is the macronutrient you need more of when calories go down, not less: it is the most satiating per calorie, and it is what limits how much of the weight you lose comes off muscle rather than fat. The protein guide has the targets.
In practice: 200 g of 0% Greek yoghurt is 20 g of protein for 118 kcal. Three egg whites are 11 g for 52. A 150 g fillet of cod, cooked, is 34 g for about 160. These are the cheapest grams of protein in a supermarket.
The raw and cooked problem starts here
Raw cod is about 82 kcal per 100 g. The same fish cooked is about 105.
No calories appeared. The fish lost roughly a quarter of its weight as water, so what remains is more concentrated — the same energy packed into less weight. The figure you should use depends entirely on when you put it on the scale.
| Raw | Cooked | |
|---|---|---|
| Cod | ~82 | ~105 |
| Prawns | ~85 | ~99 |
| Chicken breast, skinless | ~120 | ~165 |
This is the single most common source of error in food tracking, and it gets much worse with dry goods — 100 g of rice is 365 kcal dry and 130 cooked. Pick one convention, usually whichever the packet gives, and stay with it. Reading a food label covers which figure a packet means.
Potatoes are the odd one out, and they earn it
The only food on the list with no meaningful protein, and arguably the most useful one on it.
In the satiety-index research, plain boiled potatoes score higher than any other common food tested — more than three times white bread for the same calories. Whatever the mechanism, the practical version is uncontroversial: 300 g of boiled potato is 260 kcal and genuinely settles a meal, in a way that 260 kcal of almost anything else does not.
What ruins them is never the potato:
| Same potato, 100 g | Calories |
|---|---|
| Boiled | ~87 |
| Baked, plain | ~93 |
| Mashed with butter and milk | ~110–140 |
| Roasted in oil | ~150–200 |
| Chips / fries | ~310–340 |
| Crisps | ~536 |
A four-fold spread, decided entirely by the fat it was cooked in.
How the band works on a plate
This rung supplies the two things a meal needs most of — protein and starch — at prices that leave room for the rest. A worked dinner:
- 150 g cod, cooked: ~160 kcal
- 250 g boiled potatoes: ~220 kcal
- 250 g vegetables from the under-30 band: ~60 kcal
- 1 tsp olive oil and lemon: ~45 kcal
That is a full plate, 35 g of protein, and about 485 kcal. The same plate built from the under-300 band — salmon, bread, feta — would be 900 or more and no larger.
Neither is wrong. But this is the band where a deficit stops requiring willpower, which is most of why it holds.
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, cut and preparation. General information, not medical advice.