If you’re an astute reader, you may have picked up on the fact that you can also lose fat by eating only carbohydrates. This is correct because your body will have no fat to store, and your body is bad at converting excess carbs to fat. However, it will be slow without some form of fasting and exercise since your body will prefer to used stored carbs before fats. But there are more important reasons to not take this path.
First, there is strong evidence that excess carbohydrate consumption is the root of many modern diseases. The most obvious is the development of type-2 diabetes. There is also strong evidence that it leads to metabolic syndrome/heart disease (which can be detected by the symptoms of elevated cholesterol and high triglycerides). Finally, there is very early evidence that excess carb consumption is the cause of Alzheimer’s Disease.
From a practicality standpoint, there are very few foods containing only carbs, and there are even fewer that could be considered “healthy”.
You can attempt this strategy if you’d like, but don’t. You’ll thank yourself in the long run.