Adding high-intensity interval training to a very low-carb diet doesn't stop the muscle loss that happens when people with excess body fat eat very few carbs for 12 weeks.

Adding high-intensity interval training to a very low-carb diet doesn't make the belly fat reduction any better than just doing the diet alone in people with excess body fat.

Eating very few carbs and more fats for 12 weeks doesn't improve the maximum oxygen your body can use during exercise in people with excess body fat when measured in absolute terms.

When people with excess body fat eat very few carbs and more fats, they lose about 4-5% of their muscle mass within a month, and this muscle loss continues for the full 12 weeks of the diet.

Eating very few carbs and more fats for 12 weeks makes the dangerous belly fat around organs shrink by about a quarter in people who have too much body fat.

For athletes who need to make weight (like wrestlers or boxers), eating low-carb and high-fat for a long time might help them lose fat without losing muscle, which is safer than starving or sweating off weight quickly.