Have you ever felt like doing an Iron Man Triatholon every day for 10 days? If you did would you be worried about the effect on your body composition? Well a group of researchers were concerned that this could lead to loss of muscle mass so they looked at the 14 male and 3 female competitors in the 2006 World Challenge Iron Triatholon (Triatholon study).
They lost 2.4kg after the first day of their average 76.4 kg weight with a 5kg or 6.4% loss of body fat. Although there was a little gain of fat in the later stages their lean body mass and body water rose and most of the fat loss was maintained. Interestingly only 8 men and 1 woman completed and they trained on average 24 hours per week .
What does this tell you? Not much probably other than the body has an amazing ability to maintain itself even under the most extreme conditions.