One of the most frustrating parts of trying to lose weight is feeling as though you have to eat tiny portions. The good news is that you do not have to. By choosing more foods that are low in calories but high in water, fibre and volume, you can often eat a satisfying amount while still taking in less energy overall.
This guide explains the idea behind low-calorie eating, lists the most useful foods and snacks, and gives you practical swaps and meal ideas. It combines our earlier separate guides to low-calorie foods and low-calorie snacks.
Calories: the basics
A calorie is a measure of the energy in food and drink. The NHS explains that, as a guide, an average woman needs about 2,000kcal a day and an average man about 2,500kcal, depending on age, size and activity. To lose weight you need to take in less energy than you use over time, which the NHS describes as creating a calorie deficit.
The problem is that cutting calories by simply eating less of the same foods often leaves people hungry. That is where energy density comes in.
Energy density: the key idea
Energy density is the number of calories in a given weight of food. Foods with a lot of water and fibre, such as vegetables, fruit, soups and pulses, have a low energy density. You can eat a large portion for relatively few calories. Foods high in fat and sugar and low in water, such as biscuits, crisps, pastries and chocolate, are energy-dense, so even a small portion carries a lot of calories.
Research led by Barbara Rolls, summarised in the Journal of the American Dietetic Association, found that lowering the energy density of the diet allows people to eat satisfying portions while reducing their calorie intake. Rather than eating less food, you eat more of the right foods.
The most useful low-calorie foods
| Food group | Examples | Why they help |
|---|---|---|
| Non-starchy vegetables | Courgette, cucumber, lettuce, spinach, broccoli, cauliflower, peppers, mushrooms, tomatoes | High in water and fibre, very low in calories |
| Fruit | Berries, apples, pears, oranges, melon, kiwi | Naturally sweet, high in water and fibre |
| Broth-based soups | Vegetable, minestrone, lentil and tomato | Filling and warming for few calories |
| Lean protein | White fish, skinless chicken, eggs, prawns, tofu | Protein helps you feel full for longer |
| Pulses | Lentils, chickpeas, beans | Protein plus fibre in one food |
| Low-fat dairy | Plain yoghurt, skyr, cottage cheese | Protein-rich and versatile |
| Wholegrains (in sensible portions) | Oats, brown rice, wholemeal bread, wholewheat pasta | More fibre than white versions, so more filling |
Fill half your plate with vegetables
One of the easiest habits is to fill half your plate with vegetables or salad, a quarter with lean protein and a quarter with wholegrain starchy food. This naturally lowers the energy density of a meal without needing to count anything. The NHS also recommends at least 5 portions of a variety of fruit and vegetables every day.
Don't fear starchy foods
Low-calorie eating does not mean cutting out carbohydrates. The NHS recommends basing meals on starchy foods such as potatoes, bread, rice and pasta, choosing wholegrain or higher-fibre versions where you can. Gram for gram, they contain fewer than half the calories of fat. The calories often come from what we add, such as butter, creamy sauces or oil.
Low-calorie snacks
Snacks can help if long gaps between meals leave you overeating later. The aim is to choose snacks that are filling, not just low in calories.
| Snack | Why it works |
|---|---|
| An apple or pear with a few almonds | Fibre and a little healthy fat for staying power |
| Carrot, cucumber and pepper sticks with 2 tablespoons of hummus or tzatziki | Crunchy, high volume, and the dip adds flavour |
| A small pot of plain yoghurt or skyr with berries | Protein plus natural sweetness |
| A boiled egg or two | Protein-rich and easy to prepare ahead |
| A cup of vegetable or miso soup | Warm and filling for very few calories |
| Air-popped popcorn (plain or lightly seasoned) | A big bowl for relatively few calories |
| Cherry tomatoes and a matchbox-sized piece of reduced-fat cheese | Savoury and satisfying |
| Rice cakes with cottage cheese and cucumber | Crunchy and high in protein |
For more snack ideas organised by when and why you snack, see our guide to healthy snacks for weight loss.
Simple swaps that save calories
| Instead of | Try |
|---|---|
| Creamy pasta sauce | Tomato-based sauce with extra vegetables |
| Crisps | Plain popcorn or vegetable sticks with salsa |
| Fruit yoghurt with added sugar | Plain yoghurt with fresh fruit |
| Fizzy drinks or juice | Water, sparkling water with lemon, or sugar-free squash |
| Fried chicken | Grilled or oven-baked chicken |
| A large portion of rice | Half rice, half cauliflower rice or extra vegetables |
| Biscuits with your tea | A piece of fruit or a small handful of unsalted nuts |
Meal ideas built on low-calorie foods
- Breakfast: porridge made with semi-skimmed milk and topped with berries, or scrambled eggs with spinach and mushrooms on one slice of wholemeal toast.
- Lunch: a big bowl of lentil and vegetable soup, or a salad with chickpeas, roasted peppers, cucumber, tomatoes and a little feta.
- Dinner: a vegetable-packed chilli with beans, served with a small portion of brown rice and a side salad; or baked white fish with roasted vegetables and new potatoes.
- Dessert: baked apple with cinnamon and a spoonful of plain yoghurt.
How to read the label
The NHS traffic-light labels on the front of packs show whether a food is high (red), medium (amber) or low (green) in fat, saturated fat, sugars and salt. Per 100g, a food is high in fat if it has more than 17.5g of fat, and high in sugar if it has more than 22.5g of total sugars. Choosing more greens and ambers is a simple way to shop for lower-calorie foods. "Low fat" products are not always low calorie, as some contain added sugar, so compare the calories per portion.
Pitfalls to avoid
- Going too low: cutting calories too hard can leave you tired, hungry and short of nutrients. The British Dietetic Association advises avoiding fad diets, which it describes as extreme, restrictive and hard to stick with. Speak to your GP before trying a very low-calorie diet.
- Forgetting drinks: sugary drinks, alcohol and large coffee-shop drinks can add a surprising number of calories.
- Grazing all day: lots of small "healthy" snacks still add up.
- Relying on diet products: whole foods are usually more filling than processed "light" versions.
Frequently asked questions
What is the lowest-calorie food?
Watery vegetables such as cucumber, lettuce, celery and courgette are among the lowest in calories. But you need a mix of foods, including protein, wholegrains and healthy fats, for a balanced diet and to stay full.
Can I lose weight just by eating low-calorie foods?
Choosing more low-calorie, high-volume foods can make it much easier to eat fewer calories overall. Weight loss still depends on your total intake over time, as well as activity, sleep and other factors.
Are low-calorie snacks good for weight loss?
They can be, if they stop you getting overly hungry and overeating at your next meal. Snacks that combine fibre and protein, such as fruit with yoghurt, tend to keep you fuller.
How many calories should I eat to lose weight?
It depends on your age, sex, size and activity level. The NHS BMI calculator can give you a starting point, and your GP can refer you to a weight management service if you need more support.
Is fruit too high in sugar for weight loss?
Whole fruit contains natural sugars along with water and fibre, and counts towards your 5 A Day. It is a good choice for most people. Fruit juice and smoothies are different: the NHS advises limiting them to a combined total of 150ml a day.
Related guides
- High-protein foods and diet for weight loss
- High-fibre foods for weight loss
- Healthy snacks for weight loss
- The Mediterranean diet for weight loss
Sources
- NHS: Understanding calories https://www.nhs.uk/live-well/healthy-weight/managing-your-weight/understanding-calories/
- Rolls BJ et al. (2005). Changing the energy density of the diet as a strategy for weight management. Journal of the American Dietetic Association. https://pubmed.ncbi.nlm.nih.gov/15867904/
- NHS: Why 5 A Day? https://www.nhs.uk/live-well/eat-well/5-a-day/why-5-a-day/
- NHS: 5 A Day portion sizes https://www.nhs.uk/live-well/eat-well/5-a-day/portion-sizes/
- NHS: Starchy foods and carbohydrates https://www.nhs.uk/live-well/eat-well/food-types/starchy-foods-and-carbohydrates/
- NHS: Food labels https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/how-to-read-food-labels/
- British Dietetic Association (BDA): Weight loss food fact sheet https://www.bda.uk.com/resource/weight-loss.html
- NHS: The Eatwell Guide https://www.nhs.uk/live-well/eat-well/food-guidelines-and-food-labels/the-eatwell-guide/
Medical disclaimer: this guide is general information only, not medical advice. Speak to your GP or a registered dietitian before making major changes to your diet, especially if you have a health condition, are pregnant or take medication. See our Medical Disclaimer.