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Day 47: Max Weight Loss Without Muscle Loss

Today, I woke up and weighed myself. Weight is: 82.8Kg. Yesterday I consumed 12 calories below my BMR and did 206 calories of exercise above my BMR. Total deficit is 218 calories.


Understanding your maximum amount of fat loss per day without losing muscle mass is very important for athletes who participate in weight class based sports, but is also applicable to anyone losing a great deal of weight in a short period of time. Your body can only burn so many carbs and so much fat in a period of time, before it starts consuming muscle tissue to get the energy it needs.


This maximum weight loss rate is different for every person because it depends on your current body fat percentage. That also means that this rate will be different for you at different points in your weight loss journey. The maximum amount of body fat you can lose, without losing muscle mass, is about 62 calories worth of fat per day, per kilo of fat in your body. If you are on a very calorie restrictive diet with high energy burn, you need to recalculate your target deficit every week.


If you are steadily losing a great deal of weight for a long period of time, you will need to recalculate your max loss rate and also monitor your weight loss to ensure you are not losing too much. For example, let’s take where I was at a certain point my life:

  • % Body fat (start) 18%

  • Weight (start) 85Kg%

  • Body fat (Target) 10%

  • Weight (Target) 78Kg


According to my numbers, I have 15.3Kg of body fat. 15.3 * 62 = 949 Calories. That means, for the first week, the most body fat I can burn per day, is 949 calories. The first week would see me able to burn 6643 calories and lose .86Kg of body fat.



The chart above shows how the maximum amount of calories of fat I can burn changes from week to week. If I want to maintain my muscle mass, my maximum caloric deficit per week will decrease. In addition, I can achieve my goal by the end of 12 weeks. Additionally, achieving calorie targets get easier the closer I get to my target weight, and the last week is quite easy.

The important information to take from this is, if you want to maintain muscle mass, you have to carefully calculate how many calories you can burn in a week, and not go over that limit. If on the other hand, you do not care about the loss of muscle mass, then by all means, burn more calories.


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