"paleo" for hundreds of thousands of years. They have only been eating high-carb/low-fat for a few hundred, and *especially* so in the last 35 years.
So which diet, exactly, is the fad here? And during that same period, what has been the trend line for obesity?
There certainly is science to nutrition. Take a browse in this archive of 1000+ journal articles:
Browse long enough and you'll soon realise that the "everything in moderation", "a calorie is a calorie" and "eat less, exercise more" mantras are false and not based on any science whatsoever. This advice actually helps dieters justify "splurging" on unhealthy foods as long as they come in below the calorie count. Then they are left wondering why they are so hungry all the time and aren't losing weight.
It is time for the high-carb/low-fat fad to run its course and be dismissed to the dust-bin of history.