There are a few reasons why hikers can get fat. First, hiking can be an extremely physically demanding activity that requires a lot of energy. Second, hikers often eat high-calorie foods and snacks while on the trail to fuel their activities. Third, hiking can lead to overeating and weight gain if it is done for long periods of time without any physical activity in between meals. Finally, many people who hike are not physically active outside of hiking and may not be aware of the importance of exercise overall or how to properly diet for hiking purposes.