If you want to eat more nutrients without eating many more calories, the easiest wins are watery vegetables and fresh fruit. Cucumber, celery, zucchini and asparagus all come in at around 15–20 kcal per 100 grams, the cabbage family sits between about 25 and 50, and even sweet choices like watermelon, oranges and apples stay close to 30–52. For comparison, 100 grams of white bread has roughly 250 kcal and cheddar cheese around 400.
Below are fourteen of the best-value foods, grouped by type, with approximate calories per 100 grams (raw, based on standard USDA figures) and what each one actually brings to the plate. After the list you will find how to use them in everyday meals and a few myths worth dropping.
What "almost no calories" really means
Nutritionists talk about energy density: how many calories a food packs into each gram. Foods that are mostly water and fibre, like most vegetables, have a very low energy density. You can eat a large, filling portion for very few calories, and you still get vitamins, minerals and plant compounds along the way.
That is why these foods are useful for anyone trying to manage their weight. They do not burn fat or "cancel out" other food. They simply take up room on the plate and in the stomach, so a meal feels satisfying with less total energy. The UK's NHS points out that fruit and vegetables are generally low in fat and calories as long as they are not fried or roasted in a lot of oil, which is the catch to remember throughout this list.
Watery vegetables: the lightest of all
Cucumbers (about 15–16 kcal)
Cucumbers are about 95% water, so they are as much a drink as a food. They add crunch to salads, sandwiches and yoghurt dips like tzatziki. Keep the peel on; that is where most of the fibre and vitamin K sit.
Celery (about 14–16 kcal)
Celery is often called a "zero-calorie" food. It is not zero, but it is close, and it offers some fibre, vitamin K and potassium. It is great as a base for soups and stews or as a crunchy snack with a spoonful of hummus or peanut butter.
Zucchini (about 17 kcal)
Zucchini, or courgette, soaks up flavour from whatever it is cooked with. Grate it into pasta sauce, slice it into stir-fries, or spiralise it as a lighter swap for part of your noodles. It supplies vitamin C, potassium and some B vitamins.
Asparagus (about 20 kcal)
Asparagus is a good source of folate and vitamin K. Grilled or roasted with only a light brush of oil, it makes a filling side dish that feels like a treat. It is also one of the vegetables with a notable amount of plant protein for its calories.
The cabbage family: cruciferous vegetables
Broccoli, cabbage, cauliflower, kale and Brussels sprouts all belong to the same plant family. They contain sulphur compounds called glucosinolates, which are being studied for possible anti-cancer effects. Reviews of the research describe the link with lower risk of some cancers as suggestive, not proven, so treat them as healthy foods rather than cures.
Cabbage (about 25 kcal)
Cabbage is cheap, keeps for weeks and is rich in vitamins C and K. Shred it raw into coleslaw, ferment it into sauerkraut, or braise it slowly. Older claims that cabbage "prevents cancer" go further than the evidence; it is better described as part of a diet linked to good health.
Cauliflower (about 25 kcal)
Cauliflower is a flexible stand-in for higher-calorie starches. Mash it, roast it, or blitz it into "rice" or a pizza base. Keep in mind that shop-bought cauliflower pizza crusts often contain cheese and flour, so their calories can be close to a normal base.
Broccoli (about 34 kcal)
Broccoli gives you fibre, vitamin C, vitamin K and folate, plus a little plant protein. Steaming or quick stir-frying keeps more of its vitamin C than long boiling. It works in almost any savoury dish.
Brussels sprouts (about 43 kcal)
Brussels sprouts have a strong, slightly bitter flavour that turns sweet and nutty when roasted. They are especially high in vitamin C and vitamin K. Halving them before cooking helps them brown and cook evenly.
Kale (about 35–49 kcal)
Raw kale is one of the most nutrient-dense leafy greens: 100 grams provides more than the daily value of vitamin C and several times the daily value of vitamin K. Massage it with a little lemon juice for salads, add it to soups, or bake it into crisps. People taking warfarin or similar blood thinners should talk to a doctor before suddenly eating much more of vitamin-K-rich greens.
Bulbs and roots: onions and carrots
Onions (about 40 kcal)
Onions turn up in so many recipes that they quietly add up across a week. They contain flavonoids such as quercetin and some prebiotic fibre that feeds gut bacteria. Softening them in a spoon of oil, rather than a pool of it, keeps the calorie count low.
Carrots (about 41 kcal)
Carrots are famous for beta-carotene, which the body turns into vitamin A; 100 grams covers most of an adult's daily need. Vitamin A is essential for normal eyesight, but the old idea that carrots give you night vision began as British wartime propaganda to hide the use of radar. Eating more carrots will not sharpen eyes that already get enough vitamin A.
Fruit: sweet but still light
Watermelon (about 30 kcal)
Watermelon is about 91% water, which is why it feels so refreshing. It contains lycopene, the red pigment also found in tomatoes, and a little vitamin C. It does not "boost metabolism" in any meaningful way, but it is a satisfying sweet option for very few calories.
Oranges (about 47 kcal)
One medium orange provides most of a day's vitamin C along with fibre and potassium. Eating the whole fruit rather than drinking juice keeps the fibre and makes it more filling.
Apples (about 52 kcal)
Apples are the highest-calorie food on this list, but they are still light, portable and full of fibre, much of it in the skin. A whole apple tends to keep people fuller than the same calories from apple juice or a biscuit.
How to use them in everyday meals
- Fill half the plate with vegetables. It is the simplest way to lower the energy density of a meal without counting anything.
- Start with soup or salad. A broth-based vegetable soup or a large side salad before the main course tends to reduce how much people eat afterwards.
- Swap, do not just add. Replace part of the pasta with zucchini, part of the rice with cauliflower, or part of the meat in a stew with extra vegetables.
- Watch the extras. Dressings, cheese sauces and frying can turn a 25-kcal vegetable into a 250-kcal dish.
- Aim for variety. The NHS and the World Health Organization suggest at least five portions, or about 400 grams, of fruit and vegetables a day, and different colours bring different nutrients.
Other light, nutritious choices worth adding are tomatoes, beetroot, turnips, lemons and grapefruit. If you take regular medication, grapefruit is the one to check with a pharmacist first, as it interacts with several common drugs.
Myths about low-calorie foods
"Celery has negative calories." No food has been shown to cost more energy to digest than it provides. Digestion uses only a small fraction of a food's calories; for celery it is estimated at about 8%, nowhere near the 100% that would be needed.
"Eat these and you will lose weight automatically." Low-calorie foods help because they fill you up, not because they melt fat. Weight change still depends on your overall diet, activity and health.
"Fruit is too sugary to count." Whole fruit comes packaged with water and fibre, and the foods above are modest in calories. Fruit juice and dried fruit are more concentrated, so enjoy those in smaller amounts.
If you have a medical condition, are pregnant or are planning a big change to your diet, talk to a doctor or a registered dietitian first.
Sources: NHS: Why 5 A Day?; Wikipedia: Negative-calorie food; Wikipedia: Cruciferous vegetables; Wikipedia: Kale; Wikipedia: Carrot; Wikipedia: Watermelon. Original list via Besthealthpage and Healthy Food House.
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