I really like how you intertwined the source with your answer, because as you said, the original claim was picked up off of a blog online. Cardio is something that is a very useful tool when it comes to losing weight, but it can become a downside if you do not hydrate and feed your body with the necessary nutrients for your body to maintain the amount of energy it needs to burn body fat while also trying to maintain positive muscle mass. This claim can very well be true depending on the amount of cardio done weighted against how many nutrients are getting into your body on a daily basis.