I've had a look at your diary, and can see that you have set your activity levels to light which has given you a calorie allowance of 1400 calories per day.

You mention that you have recently increased your activity levels. Although you are logging these activities, it may be better to change your activity settings to moderate as this will increase your calorie allowance and compensate for this extra activity. Running three times per week is a substantial amount of exercise and it's important that you're consuming enough calories to enable you to stay healthy, and perform to your optimal level.

The feeling of light headedness/ sickness that you're getting mid afternoon could well be your body telling you that it needs extra food. Although you're having water and vegetables, it is possible that you may need extra carbohydrates as your body requires glucose to carry out a variety of activities.

Having a larger lunch may help; try increasing the amount of protein and complex carbohydrate at lunch time. This will help you to stay fuller for longer and not get this dip in the afternoon. Opt for a low fat protein such as grilled chicken, fish, egg etc with a salad and a slice of wholemeal bread, or perhaps a serving of wholegrain pasta or rice. This type of meal will optimise nutrients, give you plenty of energy and hopefully maintain a steady blood sugar level throughout the afternoon. If you feel like you need something mid afternoon, maybe try something like dried fruit or nuts which will give you a quick glucose boost and help to fill you up.

Obviously if this feeling continues once you have increased your calorie intake, made filling choices at lunchtime and perhaps introduced a sweeter snack in the afternoon, then you must seek further advice from your GP. If at any point you feel unwell you should contact your GP or NHS Direct immediately in case there is an underlying cause for your light headedness.

I hope that this helps, and wish you the very best with your weight loss. Hope you start to feel better soon.