If we want to eat keto (which we do, don’t we, boys and girls) we would never eat the suggested 50g carbs in one go. But I can see a value in a modified version of this test - using, say, 10g or 20g carb. You could use it to decide if any particular carb was giving you a problem compared to others.
Or proteins. Don’t forget they can cause both glucose and insulin responses.
For the love of everything that is holy
http://www.foxnews.com/lifestyle/2017/03/21/how-eating-carbs-can-actually-help-lose-weight.html
There actually are high carb, low fat diets that work for many people for loosing weight.
They just suck.
They also typically get rid of most the sugar (especially added sugar without fiber).
Long term health effects and factors beyond weight are another question.