Do I lose muscle mass if I do anaerobic exercises throughout my diet?

Question

I'm on a diet for a month now. It consist of 5 meals with a sum of 1700 calories per day (2000 is the stable calorie intake per day for me). My diet has a high amount of protein (3 times body mass) and a moderate amount of carbohydrates(1,5 times body mass) in it. I lose around 0,75 kilograms per week.

I decided to work out 3 times a week. A workout consists of weightlifting (bench press, squats and other assorted exercises to move every muscle in my body) and an aerobic part when I do stair stepping for at least 45 minutes. The strength training part is for preserving muscle mass and the aerobic part is for losing fat.

I've kept my heart beat rate in the aerobic range so far but after doing a research in this topic I've been conflicted by the results. I've read that in order to effectively lose fat I need to push my heart rate up to the anaerobic range but some say that it will lead to muscle mass loss because anaerobic exercise needs more energy then my system can can mobilize from burning fat. According to my research anaerobic exercise is important because it speeds up my metabolism and I can keep burning more fat even after the exercise. Aerobic exercise in the other hand only burns fat while I do it.

So what kind of exercise should I combine to the other part of my workout to burn the most possible fat while losing the least possible muscle mass?

Answer 1

Do I lose muscle mass if I do anaerobic exercises throughout my diet?

Not necessarily. In fact, typical anaerobic exercises that use your muscle, such as lifting weights as you mention in your question actually helps to preserve the muscle. It's a signal to your body that you need that muscle.

You lose muscle when you don't eat enough protein and other energy sources to rebuild the muscle after training. This is a reason that severe calorie restrictions cause loss of muscle mass.

I'm on a diet for a month now. It consist of 5 meals with a sum of 1700 calories per day (2000 is the stable calorie intake per day for me). My diet has a high amount of protein (3 times body mass) and a moderate amount of carbohydrates(1,5 times body mass) in it. I lose around 0,75 kilograms per week.

I'm assuming this is grams protein or carbohydrates per kilogram total body mass? For the purpose of discussion, let's assume you are 80kg (~175 lbs)--that would be 240g protein and 120g carbohydrates. That would leave you with about 29g of fat for the remainder of your diet at that weight.

Just a couple observations:

• .75kg / ~1.5lb per week weight loss is really good, and within the safe range.
• With the example we have here, fat intake would be what would be the minimum necessary for proper hormonal function (roughly .35g fat / kg total body mass).
• It's working, keep at it.
• If you have trouble keeping up with the work, you may want to trade some of the protein for carbohydrates. As long as you keep 2g protein per kg total body mass you will have enough to preserve muscle.

So what kind of exercise should I combine to the other part of my workout to burn the most possible fat while losing the least possible muscle mass?

Honestly, what you are doing is just fine. Lifting weights with big compound movements do wonders for your hormonal profile, the diet is good, and the aerobic work helps lower your resting heart rate. The only things I would worry about are:

• How are your measurements changing? Measuring your body parts with a tape measure provides a better picture of how your body is changing than a scale could ever tell you.
• Make sure you get 7-8 hours sleep per day.
• Relax. Avoid unnecessary stress that only serves to throw your hormones in a catabolic state. Some stress is necessary and healthy (such as the stress of training), but continual worry and anxiety keeps your body in a more catabolic state.

Answer 2

I lose around 0,75 kilograms per week.

That is a bit high. You will probably lose some muscle. Personally, I believe in slower bulk/cut.

I decided to work out 3 times a week. A workout consists of weightlifting (bench press, squats and other assorted exercises to move every muscle in my body) and an aerobic part when I do stair stepping for at least 45 minutes. The strength training part is for preserving muscle mass and the aerobic part is for losing fat.

Cardio doesn't burn fat per se. All activity burns calories, which helps you stay at a calorie deficit, but it is the calorie deficit that reduces fat storage, not cardio.
Also, there is research that shows that for best results, cardio should always be done in a seperate session, or at least before weight training. Cardio after weights interferes with the very beneficial hormonal response of weight training.

I've kept my heart beat rate in the aerobic range so far but after doing a research in this topic I've been conflicted by the results. I've read that in order to effectively lose fat I need to push my heart rate up to the anaerobic range but some say that it will lead to muscle mass loss because anaerobic exercise needs more energy then my system can can mobilize from burning fat. According to my research anaerobic exercise is important because it speeds up my metabolism and I can keep burning more fat even after the exercise. Aerobic exercise in the other hand only burns fat while I do it.

Higher intensity is almost always better. You don't need cardio for weight loss (unless you like it). Weight training creates the "anabolic" hormonal environment for all the fat loss you need.

So what kind of exercise should I combine to the other part of my workout to burn the most possible fat while losing the least possible muscle mass?

Patience. You are doing fine, you will usually lose some muscle and even some strength when cutting, it is normal. Just keep it slow.

Some tips: http://www.biolayne.com/contest-prep/best-form-of-cardio-for-bodybuilding/
https://www.youtube.com/watch?v=FcM8HablpZk

jp2code:
After about 30 minutes of cardio, your body has burned out of the sugars stored in your blood. Then, it gets energy where it can. That can come from converting fat or muscle to energy.

No, that is why you have glycogen stores...