Final answer:
When an adult loses weight through a starvation diet, around 25% to 30% of the weight loss is typically lean tissue.
Step-by-step explanation:
When an adult loses weight through a starvation diet, a portion of the weight loss is typically lean tissue. The amount of lean tissue lost can vary depending on factors such as the individual's body composition and the specific details of the diet. However, it is generally estimated that about 25% to 30% of weight loss from a starvation diet is lean tissue. This means that out of the 20 pounds lost in this scenario, around 5 to 6 pounds would be lean tissue.