For high level endurance athletes, eating enough can be a difficult task. I wouldn’t quite categorize diets like the one described in https://www.nytimes.com/2018/02/23/sports/olympics/cross-cou... as “a bad diet”, but it’s certainly a quantity and density of calories that would make it a bad diet for most people with a normal energy expenditure.
An anecdote from my experience with long trail hiking is that essentially everybody loses weight hiking long trails for months. Turns out when you’re hiking 25-30 miles / day, it’s awfully hard to not be in a calorie deficit (especially when you’re also trying to optimize for lightweight food)
An anecdote from my experience with long trail hiking is that essentially everybody loses weight hiking long trails for months. Turns out when you’re hiking 25-30 miles / day, it’s awfully hard to not be in a calorie deficit (especially when you’re also trying to optimize for lightweight food)