It's this last point that has given fat such a bad reputation. Just 1g of fat provides 9 calories - more than double the calories in 1g of protein or carbohydrate. This means if you eat a lot of fatty foods, you're likely to put on weight. However, understanding the difference between unsaturated and saturated fats can help.

Saturated fat is generally solid at room temperature and is usually from animal sources. It's found in lard, butter, hard margarine, cheese, whole milk and anything that contains these ingredients, such as cakes, chocolate, biscuits, pies and pastries. It's also the white fat you can see on red meat and underneath poultry skin. The less saturated fat you eat, the better - a high intake has been linked with an increased risk of coronary heart disease.

Unsaturated fat is usually liquid at room temperature and generally comes from vegetable sources. Monounsaturated and polyunsaturated fats are both included in this group. Unsaturated fat is a healthier alternative to saturated fat and can be found in vegetable oils such as sesame, sunflower, soya and olive; oily fish, such as mackerel, sardines, pilchards and salmon; and soft margarine.

Like fat, sugar is a concentrated source of energy and also has a bad reputation. The psychological benefits of eating foods such as jam, sweets, cakes, chocolate, soft drinks, biscuits and ice cream are fairly obvious. They taste lovely and feel like a special treat. However, it's important to keep them as just that - an occasional, special treat. Why? Because...

Government guidelines recommend that fats make up no more than 35 per cent of your diet. For the average woman, this means about 76g of fat per day; for men, roughly 100g. In reality, though, most of us have much higher fat intakes.
Ideally, we should eat sugary foods sparingly. If you'd like to cut down on fatty and sugary foods, follow these suggestions: