Poor diet and nutrition: health risks and what a balanced diet looks like

A poor diet is not one bad meal. It is a pattern over time. The NHS describes a healthy, balanced diet as eating a wide variety of foods in the right proportions, and consuming the right amount of food and drink to achieve and maintain a healthy body weight. A poor diet is one that departs from this regularly, whether by excess, by lack of variety, or both.

The NHS says the typical diet in the UK is out of balance in specific ways: too many calories, too much saturated fat, sugar and salt, and not enough fruit, vegetables, oily fish or fibre. It also says most adults in England are overweight or obese.

The NHS ties particular nutrients to particular risks. Too much saturated fat can increase the cholesterol in the blood, which raises the risk of heart disease. Eating too much salt can raise blood pressure, which increases the risk of heart disease or stroke. Regularly having foods and drinks high in sugar increases the risk of obesity and tooth decay.

In the other direction, the NHS says people who eat at least 5 portions of fruit and vegetables a day can have a lower risk of heart disease, stroke and some cancers, and that eating less red and processed meat such as bacon, ham and sausages may help reduce the risk of certain cancers such as bowel cancer.

• Heart disease and stroke: linked to saturated fat, salt and low fruit and vegetable intake.

• Obesity and tooth decay: linked to regular high-sugar food and drink.

• High blood pressure: linked to too much salt.

• Bowel cancer: the NHS says eating less red and processed meat may help reduce risk.

The Eatwell Guide shows how much of what we eat overall should come from each food group. The NHS says you do not need to get the balance right at every meal, but should try to get it right over a day or even a week. Fruit and vegetables and starchy foods should each make up just over a third of what we eat.

Beyond those, it recommends some dairy or alternatives such as soya drinks, some beans, pulses, fish, eggs, meat and other protein, and small amounts of unsaturated oils and spreads. Foods and drinks high in fat, salt and sugar, such as chocolate, cakes, biscuits, sugary soft drinks, butter, ghee and ice cream, are not needed and should be eaten less often and in small amounts.

The guide applies to most people whether or not they are a healthy weight, whether they eat meat or are vegetarian, and no matter what their ethnic origin. It does not apply to children under 2. People with special dietary requirements or medical needs may want to check with a registered dietitian.

The NHS gives some concrete figures. A portion of fruit or vegetables is 80g, and fruit juice and smoothies should be limited to a combined total of 150ml a day. Choose higher fibre or wholegrain starchy foods. Aim for at least 2 portions of fish a week, one of which should be oily. Limit red meat to 3 portions a week, and drink 6 to 8 glasses of fluid a day.

On average, the NHS says women should have around 2,000 calories a day and men around 2,500, though how much anyone needs depends on things such as how active they are. Swapping to unsaturated fats such as olive, rapeseed and sunflower oils can help lower cholesterol.

The NHS suggests simple swaps: a banana instead of a mid-morning biscuit, a side salad at lunch, a portion of vegetables with dinner and fruit with plain, lower-fat yoghurt for dessert. Choosing semi-skimmed, 1% fat or skimmed milk and lower-fat, lower-sugar yoghurt reduces saturated fat and sugar. Check food labels to compare foods.

If you need to lose weight, the NHS points to its free 12-week weight loss plan and the BMI calculator. If you have special dietary needs or a medical condition, the NHS says to ask your doctor or a registered dietitian rather than following general advice alone.

See a GP if you are worried about your weight, have an eating pattern that feels out of your control, or have symptoms such as unexplained weight loss, persistent tiredness or digestive problems. Diet is only one factor in health. Smoking, alcohol, activity and family history also matter, and your GP can look at them together.