A healthy diet may help to prevent certain long-term (chronic) diseases such as heart disease, stroke and diabetes. It may also help to reduce your risk of developing some cancers and help you to keep a healthy weight. This leaflet explains the principles of a healthy diet. It is general advice for most people. The advice may be different for certain groups of people, including pregnant women, people with certain health problems or those with special dietary requirements.
Your body needs energy to work normally and keep you alive. You obtain this energy from nutrients in the food that you eat - mostly, carbohydrates, fats and proteins. Minerals and vitamins are other nutrients that are also important in your diet to help your body stay healthy.
It is important to find the right balance between these different nutrients to achieve maximum health benefits (see below). A balanced diet generally contains food from each of the following food groups:
- Starchy foods such as bread, rice, potatoes, pasta, etc.
- Fruit and vegetables.
- Milk and dairy foods.
- Protein foods. These include meat, fish, eggs and other non-dairy sources of protein (including nuts, tofu, beans, pulses, etc).
Fatty and sugary foods are the fifth food group that you eat. However, only a small amount of what you eat should be made up from fatty and sugary foods.
In addition to the above, having plenty of fibre and water in your diet is also important for your health.
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What are the benefits of a healthy diet?
A healthy diet may help to prevent certain serious diseases such as heart disease, stroke and type 2 diabetes. It may also help to reduce your risk of developing some cancers. If you become sick, eating a healthy diet may help you to recover more quickly. Also, a main way of preventing obesity and overweight is to eat a healthy diet. If you are overweight or obese, eating a healthy diet can help you lose weight.
As well as healthy eating, regular physical exercise is also very important for health and to avoid or reduce obesity. See also the separate leaflet called Exercise and Physical Activity.
What makes up a healthy diet?
As a general rule, vegetables, fruits and starchy foods should provide the bulk of most of your meals. The remaining part of your diet should be made up from milk and dairy foods and protein foods. As mentioned above, you should limit the amount of foods and drinks that are high in fat or sugar. The dietary guidance to reduce your risk of heart disease is as follows:
Intake of saturated fat to less than 10% of total fat intake (preferably in lean meat and low-fat dairy products):
- Replace saturated fat with polyunsaturated fat where possible.
- Eat at least five portions of fruit and vegetables per day (new research has suggested that we should all aim for seven portions per day).
- Eat at least two servings of fish (preferably oily fish) per week.
- Consider regularly eating whole grains and nuts.
- Keep the amount of salt in your diet to less than 6 g per day.
- Limit alcohol intake to less than 14 units per week for men and less than 14 units per week for women. See also the separate leaflet called Alcohol and Sensible Drinking.
- Avoid or reduce the following in your diet:
- Processed meats or commercially produced foods (including 'ready meals') which tend to be high in salt and trans fatty acids.
- Refined carbohydrates, such as white bread and processed cereals.
- Sugar-sweetened drinks.
- High-calorie but nutritionally poor snacks, such as sweets, cakes and crisps.
Below, the principles of a healthy diet are explained. It is general advice for most people. If you have a specific health problem, or specific dietary requirements, this advice may not apply to you. If in doubt, you should check with your doctor. There are also some changes that pregnant women need to make to their diet. See the separate leaflet called Planning to Become Pregnant for more details.
Much of the energy (calories) in what we eat comes from carbohydrate. These are divided into two carbohydrate types:
- Complex carbohydrates - generally starchy foods such as bread, pasta, rice and potatoes.
- Simple carbohydrates - the sweet sugary foods.
There is a lot being written about how much of our food should be made up of carbohydrates but most of the guidelines recommend about one third. This should be mostly starchy carbohydrates, preferably higher-fibre options such as wholemeal bread, wholegrain cereals and brown rice.
The glycaemic index of a food is the rate at which the food raises blood sugar levels after it has been eaten. If a food has a low glycaemic index, it is processed by the body in a way which means it is less likely to lead to problems such as diabetes and obesity.
Higher-fibre carbohydrates, such as wholegrain cereals and wholemeal bread, tend to have a lower glycaemic index than more refined starches such as white bread, snack foods and sugary drinks. This means they are a healthier option for this reason as well as for the fibre they contain.
Eat plenty of fruit and vegetables
New research suggests that eating at least seven portions of fruit and vegetables daily reduces the risks of many illnesses, such as stroke, heart disease and some cancers. Ideally there should be more vegetables than fruit in your diet. In addition to these benefits, fruit and vegetables:
- Contain lots of fibre which helps to keep your bowels healthy. Problems such as constipation and diverticular disease are less likely to develop.
- Contain plenty of vitamins and minerals, which are needed to keep you healthy.
- Are naturally low in fat.
- Help to make you feel full after a meal but are low in calories.
An average portion of vegetables may be about a handful, or about 80 g. Alternatively, one portion of fruit or vegetables is roughly equivalent to one of the following:
- One large fruit such as an apple, pear, banana, orange, or a large slice of melon or pineapple.
- Two smaller fruits such as plums, kiwis, satsumas, clementines, etc.
- One cup (or a handful) of small fruits such as grapes, strawberries, raspberries, cherries, etc.
- Two large tablespoons of fruit salad, stewed or canned fruit in natural juices.
- One tablespoon of dried fruit.
- One glass of fresh fruit juice (150 ml).
- About three heaped tablespoons of any vegetable.
- One dessert bowl of salad.
Some tips on how to increase fruit and vegetables in your diet include:
- Try some different types that you have not tried before. The variety of tastes and textures may be surprising. Frozen, canned and dried varieties all count.
- Try adding chopped bananas, apples, or other fruits to breakfast cereals.
- Aim to include at least two different vegetables with most main meals. Do not over-boil vegetables. Steaming, stir-frying, or lightly boiling are best to retain the nutrients.
- Try to have fruit with each meal or a small glass of fruit juice.
- Try new recipes which include fruit. For example, some curries or stews include fruit such as dried apricots. Have fruit-based puddings. Fruit with yoghurt is a common favourite.
- Consider cherry tomatoes, carrot sticks, dried apricots, or other fruits as part of packed lunches.
- Fruit is great for snacks. Encourage children to snack with fruit rather than with sweets.
Eat plenty of fibre
There are two types of dietary fibre:
- Soluble fibre, which is found in oats, peas, beans and many fruits and vegetables, dissolves in water to form a gel-like material. It increases feelings of fullness and can lower blood cholesterol and glucose levels.
- Insoluble fibre is mostly found in whole grains, and also in fruit and vegetable skins. It is not digested by the body but forms bulk in the gut, which helps to keep the bowels moving normally.
Starchy foods and fruit and vegetables contain the most fibre. So the tips above on starchy foods and fruit and vegetables will also increase fibre. If you switch to wholemeal rice and pasta, and wholemeal bread, this can significantly increase your fibre intake. Pulses like lentils and beans are also full of fibre.
Eating higher-fibre foods can make you feel full for longer, which can help if you are trying to watch your weight.
Have plenty to drink when you eat a high-fibre diet (at least 6-8 cups of fluid a day).
Eat enough milk and dairy foods
Milk and other dairy foods such as cheese and yoghurt are important in your diet, as they provide calcium which is needed for healthy teeth and bones. They are also a source of protein and can provide other vitamins and minerals important for your health. Calcium-enriched soya milk and fromage frais also come under 'milk and dairy foods'. However, other foods such as butter and cream are not considered as dairy foods here, as they are also high in fat, so they come under the fatty foods group.
To make sure that you have enough calcium in your diet, you need three servings a day from this food group. One serving is:
- 200 ml of milk.
- A small (150 g) pot of yogurt.
- A 30 g serving of cheese (about the size of a small matchbox).
As the fat content of dairy foods can vary, make sure that you go for lower-fat options where possible, such as skimmed or semi-skimmed milk, low-fat cheese and low-fat yoghurt.
Non-dairy sources of calcium include leafy green vegetables, tinned fish (particularly if the bones are included), dried figs, almonds, oranges, sesame seeds, seaweed and some types of beans.
Non-dairy calcium needs to be eaten with a source of vitamin D, as the body needs this to help it absorb the calcium. Vitamin D can be found in eggs, fish and mushrooms but is mostly made in the skin by contact with sunshine.
Some foods are fortified with calcium, such as breakfast cereals, some soya drinks and tofu. These may already have added vitamin D.Clean eating
Clean eating is not an innocent trend that’s come along to counter unhealthy diets. It’s simply an eating disorder by another name and in the unit I work in, it’s an epidemic.— Dr Max Pemberton, Connections between 'clean eating' and orthorexia
Eat other protein foods in moderation
Other protein-containing foods include meat, fish, eggs and plant sources of protein. Plant sources of protein include nuts, seeds, tofu, beans such as red kidney beans and canned beans, and pulses such as lentils and chickpeas.
You need a certain amount of protein to keep healthy. Protein is important for energy and for growth and repair in your body. Some of these high-protein foods can also be a source of iron and vitamins, including B vitamins and vitamin D. However, most people eat more protein than is necessary. Beware, some meats are also high in fat. Choose poultry such as chicken, or lean meat. Also, be careful, as many meat-based recipes include creamy or fatty sauces which are high in calories. When eating eggs, boil or poach them instead of frying. One portion of beans or pulses such as chickpeas or lentils is three heaped tablespoons.
There is some evidence that eating oily fish helps to protect against heart disease. Oily fish include herring, sardines, mackerel, salmon, fresh tuna (not tinned), kippers, pilchards, trout, whitebait, anchovies and swordfish. It is thought that omega-3 fatty acids in the fish oil help to reduce 'furring of the arteries' (the build-up of atheroma) which causes angina and heart attacks. Aim to eat at least two portions of fish per week, one of which should be oily.
Vegetarian sources of protein do not provide the correct balance of amino acids (the building blocks of proteins) for the body to use unless combined with each other. So people who are not eating a lot of fish, meat or eggs need to make sure that their meals contain two of the following:
- Dairy products.
- Legumes (for example, beans, lentils).
Examples of protein-balanced meals are:
- Baked beans on toast.
- Dhal and rice or chapatti.
- Baked potato with baked beans and cheese.
- A bowl of cereal with milk.
Red meat and processed meat
Red meat refers mainly to beef, veal, pork and lamb. Processed meat refers to meat that has been processed to improve the flavour or to help preserve the meat. Examples of processed meat include ham and sausages, as well as canned meat and meat-based ready meals and sauces.
There is evidence that eating red and processed meat increases the risk of bowel cancer.
Eating red and processed meat has also been shown to increase the risk of stroke, heart disease and type 2 diabetes. The health risks from eating processed meat increase with increasing amounts of processed meat that you eat.
On the other hand, restricting the intake of meat can increase the risk of iron-deficiency anaemia. For this reason, the UK Government's Scientific Advisory Committee on Nutrition (SACN) recommend that your intake of red and processed meat should be no more than 70 g/day.
For a long time, obesity and many other health problems have been blamed on the amount of fat that we eat. This makes sense because fat contains about twice as many calories as carbohydrate or protein per gram. However, more recent research suggests the picture is more complex than that. It suggests that carbohydrate plays a larger role in weight gain than we previously thought.
Also, the advice about which types of fats are better to eat has been under discussion. It was previously thought that saturated fats (mostly from animal sources like meat and butter) were more dangerous to health than polyunsaturated fats. Polyunsaturated fats are generally found in vegetable oils. Recent research does not support this view.
It probably is still a good idea to eat less fat if you are trying to lose weight.
Tips to reduce fat in your diet include the following:
- Whenever possible, do not fry food. It is better to grill, bake, poach, barbecue or boil food. If you do fry, use unsaturated oil. Drain the oil off the food before eating.
- Choose lean cuts of meat and cut off any excess fat.
- Avoid adding unnecessary fat to food. For example, use low-fat spreads, spread less butter or margarine on bread, measure out small portions of oil for cooking, etc.
- Watch out for hidden fats that are in pastries, chocolate, cakes and biscuits.
- Have low-fat milk, cheeses, yoghurts and other dairy foods rather than full-fat varieties.
- Avoid cream. Use low-fat salad cream, or low-fat yoghurt as a cream substitute.
Trans fats (or trans fatty acids) are unsaturated fatty acids. Trans fats increase the risk of heart disease. They increase LDL cholesterol and decrease HDL cholesterol. See also the separate leaflet called High Cholesterol for further information.
Trans fatty acids occur naturally in small amounts in a wide range of foods, such as milk, beef and lamb. However, most of the trans fatty acids in the diet are produced during the processing of vegetable oils. Trans fats are therefore found in hard margarines and in some baking products (for example, biscuits, pastries and cakes), fried foods and other processed foods. Foods that are labelled as containing partially hydrogenated oils or fats contain trans fatty acids. When buying fat-containing foods, it is much healthier to buy ones labelled with a high content of mono-unsaturates or polyunsaturates.
Research has shown that trans fatty acids produced during the processing (hardening) of vegetable oils are much more harmful to health than natural trans fatty acids (for example, in milk, beef and lamb). You can reduce your intake of trans fats by avoiding or reducing the amount of fried foods, high-fat snacks and high-fat baked foods you eat.
In the UK the intake of trans fats is much lower than it was 20-30 years ago. However, as part of a healthy diet, you should aim to keep both the amount of saturated fats and trans fats to a minimum.
A 2019 review by the SACN determined that reducing your intake of saturated fats lowers your risk of developing coronary heart disease, although there was no evidence that it reduces the rate of dying from these conditions. Trans fats were associated with an increased risk of heart disease and stroke. The review recommended that the intake of both saturated fats and trans fats should be kept to a minimum.
Don't have too many sugary foods and drinks
Sugary foods and drinks are high in calories and too much may cause weight gain. It isn't just the amount of sugar that may be bad. Even eating small amounts of sugary foods (sweets, etc) too often is bad for teeth. Tips include:
- Try not to add sugar to tea, coffee and breakfast cereals. Your taste for sweetness often changes with time. Use artificial sweeteners only if necessary.
- Reduce sugar in any kind of recipe. Use fruit as an alternative to add sweetness to recipes.
- Try sugar-free drinks. Give children water or milk as their main drink.
- If you eat chocolate or sweets, try to keep the quantity down.
Don't eat too much salt
Too much salt increases your risk of developing high blood pressure. Guidelines recommend that we should have no more than 6 g of salt per day. (Most people in the UK currently have more than this.) If you are used to a lot of salt, try gradually to reduce the amount that you have. Your taste for salt will eventually change. Tips on how to reduce salt include:
- Use herbs and spices rather than salt to flavour food.
- Limit the amount of salt used in cooking and do not add salt to food at the table.
- Choose foods labelled 'no added salt'.
- As much as possible, avoid processed foods, salt-rich sauces, takeaways and packet soups which are often high in salt.
Don't forget portion sizes
You may be eating very healthy foods but you still need to keep an eye on your portion sizes because if they are too large, you will still gain weight. Deliberately try to take smaller portions when you have a meal. Do not feel that you have to empty your plate. Perhaps change the plates that you have in your cupboard (which may be large) to more medium-sized plates. In this way you will naturally serve up smaller portions. Fill up on fruit and vegetables. Ask for a smaller portion when eating out or ordering a takeaway.
Think about what you are drinking
Many drinks, including alcoholic and many non-alcoholic drinks, contain calories. Think about what you are drinking.
- Choose healthier non-alcoholic drinks. Some tips: water contains no calories and can be both refreshing and healthy. Add a slice of lemon or lime to your water. Keep a jug in the fridge so that it stays cool. Also, think about switching your whole-milk latte coffee for a coffee made from skimmed or semi-skimmed milk.
- Keep alcohol within the recommended limits. Drinking above the recommended limits can lead to serious problems. For example, drinking heavily can damage the liver, brain, stomach, pancreas and heart. It can also cause high blood pressure. Also, alcohol contains a lot of calories and too much can cause weight gain:
- One unit of alcohol is 10 ml (1 cl) by volume, or 8 g by weight, of pure alcohol. For example, one unit of alcohol is about equal to:
- Half a pint of ordinary-strength beer, lager, or cider (3-4% alcohol by volume); or
- A small pub measure (25 ml) of spirits (40% alcohol by volume); or
- A standard pub measure (50 ml) of fortified wine such as sherry or port (20% alcohol by volume).
- There are one and a half units of alcohol in:
- A small glass (125 ml) of ordinary-strength wine (12% alcohol by volume); or
- A standard pub measure (35 ml) of spirits (40% alcohol by volume).
- Men should drink no more than 14 units of per week, spread evenly over several days and with at least two alcohol-free days a week.
- Women should drink no more than 14 units of alcohol per week, spread evenly over several days and with at least two alcohol-free days a week.
- Pregnant women. Advice from the Department of Health states that: ... "pregnant women or women trying to conceive should not drink alcohol at all".
- One unit of alcohol is 10 ml (1 cl) by volume, or 8 g by weight, of pure alcohol. For example, one unit of alcohol is about equal to:
Further reading and references
Cardiovascular disease: risk assessment and reduction, including lipid modification; NICE Guidance (July 2014 - last updated 2016)
Glycaemic Index; diabetes.org.uk
The Eatwell Guide; Public Health England, 2018
Saturated fats and health; Scientific Advisory Committee on Nutrition, 2019
Scientific Advisory Committee on Nutrition Iron and Health Report; Public Health England, February 2011
Mehta SS, Arroyave WD, Lunn RM, et al; A Prospective Analysis of Red and Processed Meat Consumption and Risk of Colorectal Cancer in Women. Cancer Epidemiol Biomarkers Prev. 2020 Jan29(1):141-150. doi: 10.1158/1055-9965.EPI-19-0459. Epub 2019 Oct 1.
Key T et al; Diet, nutrition, and cancer risk: what do we know and what is the way forward? BMJ 2020 368 doi: https://doi.org/10.1136/bmj.m511 (Published 05 March 2020)