I'm a 25 year old male weighting about 165 Lbs. I'm trying to lose some body fat, but I'm still going to the gym 4 days a week to prevent as much muscle mass loss as possible.

I'm consuming slightly more than a gram of protein per Lb of body weight, but I'm concerned that this protein might be going to waste because the body might not have the calories to properly repair muscle after a workout, resulting in a net muscle loss. I'm currently consuming about 2,000 calories on workout days, and about 1200 calories on rest days, for an average of about 1,800 calories a day.

Is it at all possible to lose muscle like this? Does my concern have any grounds? If so, how can I prevent it? Fat loss is my priority right now, but I want to lose as little muscle as possible.

  • You are going to the gym >3 times a week, you are eating around 1g/lb bodyweight protein, you are eating around 1800k calories. You may lose a tiny amount of muscle, but not in any visual way. You just need to hold on while losing weight to convince yourself what is dropping off is fat and not muscle. (Just don't expect to progress linearly on your weightlifting numbers)
    – John
    Sep 16, 2016 at 7:07
  • This also largely depends on the amount of amino acids in your diet and the amount of carbs you take around workouts.
    – 0xMert
    Sep 16, 2016 at 18:06

3 Answers 3


Obviously the amount of protein and carbohydrates in the diet are crucial while you're going in a deficit.

First of all, training with weights is going to decrease the catabolism in your muscle tissue ( catabolism is a wide concept, and always occur in your body in different contexts ).

This is due to the molecular axe Akt-mTORC1 and their downstreams. The anabolic nature of this axe will prevent you from loosing more lean tissue than you would if you didn't actually train while you are in a deficit. This particular pathway is enhanced also by the pulsatile secretion of testosterone due to training, and so has a good protective effect.

You have to consider that this process is happening even while you are on a hypercaloric regimen and trying to bulk up. But in this particular scenario you're in its blunted depending on you dieting pattern. I'll explain you how:

  • Caloric deficit amplitude: If your caloric deficit is too high you will not replenish efficiently your muscle glycogen stores; this substrate is actually of prime need when you have to train and its the first choice of the muscle in caloric deficit. Only after a large part of your glycogen is replenished you will actually start build muscle tissue. This is because of AMPK that is hierarchically higher than mTORC1. If AMPK senses that the energetic status of the muscle cell is too low, it will phosphorylate TSC2 ( another protein complex ) that will in sequence block mTORC1 from inducing its anabolic benefits.
  • Macronutrients ratio: If you go really high on proteins ( thus amminoacids ) you will have ( expecially from leucine ) a positive stimulant effect on the axe Akt-mTOR, but take in consideration that this is hierarchially INFERIOR to the action of AMPK ( this has some biological fundation - a cell will never go through mitosis, even though its not the case of muscle cell, if energy levels are not high enough to support its course ). So you want to have a high carbs/protein:fats ratio. Never understimate the power of carbohydrates.

What you want to do is having the smaller deficit possible and recharge your glycogen stores on rest days ( you can do this by having a calorie/week deficit but eating more, and expecially carbs, on rest days ).

To answer your question: yes, you can and will lose muscle mass but the magnitude and the onset of this loss will depend by several factors you didnt even mention.

  • How long you've been training
  • How is your weekly calorie deficit
  • What is the bodyfat you're aiming to
  • How is your training ( very important )
  • This is a very underrated answer. Do you think that doing weightlifting during a deficit is the best exercises to help preserve muscle mass while on a cut over exclusively HIIT / Low Intensity Cardio? Under the basic principle of "use it or lose It"
    – John
    Dec 16, 2016 at 7:38

Take this as a very extreme answer, and not something that you put into practice, but rather as an example. I used to fast every other week for three days, in order to allow myself to eat like a normal unhealthy person in front of my friends. This lasted for about two months. I would phase out of the fast by gradually building up to carbs in time for the weekend, and I managed to keep weight gain minimal on the binge days. I worked out the same regardless of the fast, and usually by the third day I could see that my muscles were smaller when I flexed, but I was no less strong, and I never had any problem with the workout. After a few days of carefully eating lean protein and lots and lots of raw fruits and vegetables, I would always see my muscle increase in size. In retrospect, I made a lot of physical gains during that time, although the eating habits were not very smart. I had increased my strength and endurance. I took photographs throughout, and a few weeks after I stopped fasting, got my eating in order, and continued to workout in the same way, I definitely had permanent muscle gains.

If you are gaining strength, but losing mass, don't worry. Eventually this will even out, if you lose enough weight, the areas that we generally expect to look muscular will, due to less fat surrounding everything. Let me know if was helpful!


That depends on your training. If you focus only on cardio, there are chances you may lose muscles mass over long run. Muscles feed on calories, so they need constant feeding in order to maintain the mass. Sometimes what feels like muscle loss, is lack of glycogen in muscles. So once you eat right and workout, they will gain size again. Without strength training/resistance training, you won't be able to maintain the muscle mass in long run.

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