dieting and running

Hi I have recently started tracking my running and weekly weight loss and seing some benifits, how ever I want to make sure its fat I lose not muscle, I am wandering that if cutting back on food while increasing my run mileage per week by about 15 miles may be giving me the wrong kind of weight loss, have any of you got any clear ideas on making sure i lose body fat with my runs rather than muscle.

thanks.

matthew cleary wrote (see)

....cutting back on food while increasing my run mileage per week by about 15 miles......

You're doing 15 miles more each week than the previous week? You're increasing your mileage too quick and will end up with an injury. There's no rush. Eat right and keep up the exercise and you'll lose weight over time (if you're overweight).

oops na have icreseaded it 15 miles b4 the diet to around 20 - 30 a week will not increase much more than that, also this week the scales gave me bad news despite my efforts and scafell pike last week, dose weight shift every week or do you always get 1 in 2 weeks a non loss or evan small gain. ?

I successfully lost weight while marathon training.  I worked on a 500 cal deficit per day, so in very rough terms that's 2000 cals per day (2500 for blokes) plus whatever calories I used through running (for me that is about 550 cals per hour) minus 500.

So on days that you are running 15 miles that is 2500 (basic) +1500 (exercise) - 500 = 3500 cals very approx.

I cut back on simple carbs mainly and tried to eat more protein.  If you cut back on protein then your body can't repair and build muscle so it is important that you continue to eat meat, fish, eggs, pulses etc.  Protein and fat are the things that tells your body that it is full so eating more protein and not reducing your fat intake can help reduce the amount you eat over all.

Complex carbs are still good as they give you the energy to run but most people eat too much of them.  Don't cut out any food group completely but sugary foods should be reduced significantly and be careful about carb loading

TimR and Super Caz

Cut and save your replies for future requests. 

I can't remember reading (IMO) such accurate answers on this subject. And I'm a right nerd about this sort of thing.