What is a major issue with the "fat-burning zone" related to effective weight loss?

The concept of the "fat-burning zone" refers to the heart rate range where the body predominantly utilizes fat as a source of energy during exercise. While this does indicate a greater percentage of calories coming from fat at lower intensities, the total caloric expenditure during these activities can be quite low compared to higher intensity workouts.

In the context of weight loss, the primary factor is the total number of calories burned, rather than the source of those calories. During low-intensity exercise associated with the fat-burning zone, while a higher proportion of energy may come from fat, the absolute number of calories burned can be insufficient to create a caloric deficit necessary for significant weight loss.

Alternatively, higher intensity workouts, although they may have a lower percentage of fat utilization during the activity itself, typically result in greater overall caloric burn. This leads to a more effective pathway for weight loss when coupled with proper nutrition, even if fat isn’t the predominant fuel source during the exercise. Therefore, the major issue with the fat-burning zone is its low caloric expenditure, which can hinder weight loss efforts.