Am I Losing Muscle During a Water Fast?

Monday, September 21 2020

I am on Day 8 of a water fast. My body weight is 106 pounds, about 10 pounds less than when I started. Weight loss during a water fast comes from water, carbohydrate, fat and possibly muscle.  I want to know how much muscle loss happens and, ultimately, the best way to preserve it during a water fast lasting 10 days.

At the True North Health Center they suggest only gentle movement and mostly rest. There are other schools of thought that suggest exercise is beneficial during a fast.

From what I can see, an important factor in muscle loss potential is time into the fast.  The first 3 days or so are the time when the body loses stored carbohydrate with the associated water, salt with the associated water and muscle proteins.

 Dr. Joel Fuhrman is a respected MD who has done extensive research and clinical work with fasting and nutrition. Dr. Fuhrman, who has fasted thousands, says that muscle loss decreases to less than 0.2 kg (.44 lbs) per day once full ketosis is reached, usually by the third day.  As always, all the changes pivot on an individuals body composition, fitness, general health, diet, etc.

Ketosis is the buzz word for high protein, low carb diets. Ketosis happens when you have metabolized the stored liver and muscle glycogen (carbohydrate). Ketone bodies are made from fat by the liver and become fuel that feeds the brain. During regular food intake nutritional ketosis is typically consumption of less than 50 grams of carbohydrate per day.*

Dr. Peter Sultana MD at True North Health Center answered my questions below.

Question  When does the body start catabolizing muscle protein?

• It is different for everyone
• An estimate is >40 days, or when you have reached 80% of ideal body weight. It then becomes starvation where the body metabolizes proteins for fuel.

Question  During a water fast, when is the onset of strength loss?

• Strength drops right away, but that is not muscle structure loss, that is fuel and hydration loss inside the muscles. The structure is still there, and they refill well when resuming eating. If you reached the starvation mode explained above, then they need to rebuild.

Ultimately, the impact of a 10 day water fast for me will be in how I feel when I get back to my regular workout routine.

Stay Tuned…

For more information about digestion, fasting and your overall health, contact Dorothy Sager at SynergyWellnessNW.

*Fuel4mance, September 2012 Newsletter. Dina Griffin, Sports Dietician