It's not about carbs

A good diet is not necessarily a low-carb diet. It's a low-toxin diet.

Primary known toxins:

• excess sugar (particularly fructose?)
• excess linoleic acid (omega-6)
• wheat and soy
• trans fats

Similarly: a good diet is not necessarily a high-fat diet. It's a high-nutrient diet.

Some important nutrients:

• Fat-soluble vitamins ADEK
• Magnesium
• Zinc
• Selenium
• Omega-3 fatty acids
• Copper
• Potassium
• Other vitamins BCE
• etc.

The SAD is dangerous not because it's high in calories, or fat, or sugar, or salt. It's dangerous because it's high in toxins, substances (or quantities) that are outside the human evolutionary experience.

A Paleo or Primal diet is healthy, but not because it's low in carbs or high in fat. It's healthy because it's relatively low in toxins and relatively high in essential nutrients.

Macronutrients hardly matter at all. Evidence: Inuit and Masai high-fat diets vs Kitavan high-carb diets. Both are completely fine as long as you get lots of nutrients and avoid toxins. Keep the same macronutrient ratios and add toxins and subtract micronutrients, and you get a lot of very sick people.