Nutritional therapist Julia FitzGerald offers easy tips for healthier living. This week: surviving the post-lunch slump

Do you feel tired and irritable after lunch and reach for a sugary snack to get you through the afternoon? If so, erratic blood sugar levels could be the problem.

In the first of this new series on nutrition, I'm going to suggest some simple dietary changes that could immediately improve your concentration and energy levels.

Carbohydrate-rich foods, such as bread and pasta, sweets and crisps, fuel our bodies by releasing sugar into our blood supply. But when blood sugar is low, it's like running out of fuel.

The brain is particularly sensitive to this, so headaches, irritability and brain 'fog' - inability to concentrate - are common symptoms.

Skipping meals is an obvious cause, but so are those high-sugar snacks, which send blood sugar levels soaring, only to be followed by a crash that leaves you tired and craving more carbohydrates.

The good news is that the sugar monster is easy to tame. Try these dietary tips and see if they boost energy and brain function:

Make sure   you eat three meals a day, with two or three snacks in between.

To slow the absorption of carbohydrates,   ensure that every meal contains both protein and fat. Add a spoonful of nuts and seeds to your breakfast cereal, or switch to Dorset Cereals Really Improve basic salads by adding tuna or a hard-boiled egg, and drizzle with an oil-based dressing such as vinaigrette.

Replace sugary snacks   with healthier options, like a handful of nuts and dried fruit or vegetable sticks and hummus.

Choose wholegrains   (brown rice, pasta and bread), not white bread, pastries or biscuits. The former contain more fibre, which slows the release of sugar.