There is truth in it. It is science taken out of context..
Eating carbohydrates does spike insulin.
And insulin does inhibit body fat breakdown ACUTELY.
This makes sense.. if you have food (energy) coming in why would you continue to breakdown stored energy (fat).
What low carb zealots like Taubes do is take this out of context and lead you to believe that eating carbs will prevent you from losing body fat independently of energy balance.
Another common argument I hear is that fat oxidation rates go up on low carb diets.. again, this is true!
Because low carb diets tend to be high fat diets.. and what happens when you eat more fat? You burn more fat. It does not mean that you are reducing your body fat levels!