There is an extensive amount of research that proves the claim "a beef-only carnivore diet is the healthiest diet" is false. To begin with, the article that you linked does not support this claim. Although it provides a story from an individual who experienced benefits from a carnivore diet, the point of the article is to demonstrate how difficult it is to live on a carnivore diet and all of the daily struggles and side effects that come with it. In your description, you state that "beef has all the nutrients that you need", which is also completely false. Although it is true that eating only beef provides a person with a substantial amount of protein, cutting out other food groups such as fruits, vegetables, and grains can be detrimental to a person's health. In an article by Tara Smith, a registered dietitian, and instructor of nutrition, she states that eating a full diet that includes all suggested food groups "decreases all-caused mortality, heart disease, obesity, type 2 diabetes, and some cancers". Additionally, Howard E. LeWine, the chief medical editor for Harvard Health Publishing, states that the carnivore diet introduces a large number of health risks, including "an increased risk of kidney stones, gout, and osteoporosis". Because of this research and more, it is reasonable to conclude this claim is entirely false.