There was some research a while back that indicated women who were dieting displayed reduced mental performance during tasks that require information processing. The reason given was that slimmers get so preoccupied with their diet it ends up impairing mental functioning. Fortunately a food diary approach is so reassuring, that it helps you not to obsess.

There?s also some evidence that people who have been depressed may suffer a reoccurrence of their depression if they diet drastically. Again, not making sudden or large decreases in calorie intake, and adopting sensible eating and exercise habits that allow for gradual weight loss seem to be the answer.

There may also be a linked between low intake of certain nutrients and depression, so follow these tips to keep feeling perky:

1. Eat oily fish

Studies shows that people who eat diets high in omega-3 fats from oily fish have a lower incidence of depression. Whilst you are dieting, eat oe or two oily fish meals a week - such as herrings, mackerel, sardines or salmon - to offset any negative effects on mood. If you can?t stand oily fish go for a fish oil supplement.

2. Go for slow burn carbs

Don?t cut out carbohydrate altogether - just reduce sugary foods and refined carbohydrates (in white bread, biscuits and cake - including the reduced fat sort). Swap these for more of the slow-releasing types such as porridge, Granary bread, beans and lentils. Eating slow burn carbs minimises the blood glucose fluctuations which can cause mood swings.

3. Don?t cut out the foods you enjoy.

Depriving yourself of tasty food is sure to make you feel depressed, so avoid cutting out favourite foods. Successful diets allow you to incorporate the foods you enjoy in moderate amounts.

4. Keep a sense of perspective

Losing weight is only one aspect of your life. When you have plenty of other interests, dieting is less likely to preoccupy your mind to the point where you can?t concentrate or be happy!

Finally keep active; exercise increases levels of naturally occurring mood enhancers called endorphins. Regular exercise also improves the ability to cope with stress, and improves the quality of sleep. Five 30 minutes activity sessions a week (brisk walking will do nicely) will help you beat the dieting blues.