Primary, secondary, and tertiary sources may all be appropriately used, if (1) they are used without engaging in original research or synthesis and (2) if in the event of conflicts between sources they are treated with the appropriate deference to the better source.
There is some evidence that a low-carbohydrate diet may help people lose weight more quickly than a low-fat diet (31,32)âand may help them maintain that weight loss.
Note on Saturated Fats and Low-Carb Diets. The Atkins Diet, LCHF, and most other low-carb approaches don't emphasize reducing saturated fats as long as carbs are kept low. They point to the lack of evidence that reducing saturated fats to extremely low levels is helpful in terms of risk reduction for most people.