The general problem with doing both at the same time is that to lose fat you need to reduce your calorie intake and do cardiovascular exercises whereas to build muscle you need to increase your calorie intake and do weight training. So to do both you need to make two opposites work together so that they can help you achieve your goals.
The most important thing with this is your timing because you need to make sure that you have the benefits of fat burning and the benefits of muscle building. It is almost impossible to completely combine to two but you can partially combine the two through a schedule which tells you what workouts to do and when. Moderation in your workouts is important as well so you do not injure yourself through excessive training.
Your schedule should always start with cardio training in the morning. The reason for this is that with cardio training you can keep your body burning body fat for the duration of day even when you are not exercising. The type of cardio you should be doing in the morning is not too strenuous as all you will have to do is walk on a slightly inclined treadmill for something like 45 minutes.
This will allow your body to burn fat throughout the cardio and after your body will still be in the frame of mind to burn fat. In the afternoon you should be looking at doing weight training as your body will have burnt enough fat during the day and in the evening you can start to build your muscle. It is up to you what muscle you choose to build but you should be looking at doing 3 sets of 15 reps on whatever piece of equipment you are looking at. This should be completed at least 4 hours before you go to bed so that your body has enough time to rebuild before you go to sleep.
The day after this training you should try to do a form of High Intensity Interval training (HIIT) which is basically training that requires you do hard cardio work with intervals. An example of this would we doing a jog/run exercise where you sprint for 20 seconds and then jog for 40 seconds which you should repeat around 10 times. This should be then finished with a warm down period of 4 minutes in which you take a light jog. This is all you have to do for the 2 days and this should be repeated until the seventh day when you are meant to rest and recover.
Your diet will be very influential in all of your training because dieting itself can harm your body and make it harder for you to burn fat. During the mornings you should be having a low calorie/ carbohydrate meal so that when you are doing the cardio exercise your body will be burning off fat. This should be for Breakfast and Lunch so that your body can continue to burn fat throughout the day. When it comes to the evening your diet sort of changes completely as you will need a high carbohydrate meal paired with a lot of protein. This will give your body the required energy to build its muscle once the workout is complete.
Once you have done the workout you should be looking at having some extra protein supplements so that your body can use it once again for your muscles. On the days where you are not doing any weight training or if you are having a rest day then you should stick with a low carb diet as this is all that you need.
Some people do prefer breaking their 3 main meals up into 6 smaller meals. This gives your body more energy throughout the day and without the negative effects of dieting. However if you are doing weight training this meal needs to be taken in one go so that you definitely have the required nutrients for the workout.
By doing all of this you will reach the goals of burning fat and building muscle. This will be a lengthy process so it is important for you to remain patient so that your body has enough time to help you reach the goals that you require. But once you have reached your goals it is important for you to stay there by developing habits that you cannot break.
Arnold Nevsky has written this and many other articles with the assistance of Muscle Finesse. The company is a supplier of protein powders based in the UK, and has much experience in their industry, which meant they could help Arnold as he wrote.