Carb backloading is a diet strategy that is based on the idea that eating fewer carbs in the morning and more carbs at night is the best way to lose weight. This approach claims that because cortisol levels are high and insulin sensitivity is low in the morning, it is best to avoid eating carbs because under these conditions they are more likely to be stored as fat. It suggests eating meals of mostly protein, training midday, and then adding carbs to your meals for the last several meals to get the most muscle and least fat gains.

However, this approach is not supported by scientific evidence. As mentioned in the critique of butter-in-coffee, high morning cortisol levels do not actually cause more carbs to be stored as fat; cortisol is reduced by the consumption of carbs. In addition, insulin sensitivity is higher in the morning (post-night-long-fast) than it is in the evening, so that part is simply incorrect.

Eating carbs in the morning or at night does not affect weight loss or muscle gain. The body will process the carbs and use them for energy regardless of the time of day they are consumed. The hormone logic does not add up for carb backloading and related diets. Furthermore, if you wake up and do not eat carbs for hours your insulin sensitivity might be higher than normal by the evening due to prolonged time spent without carbs (prolonged time without carbs also increases risk of muscle catabolism due to energy needs and so the purported benefit of this strategy is negated).

In conclusion, Carb backloading is a myth that is not supported by scientific evidence. Losing weight and gaining muscle require a balanced diet and regular exercise. The timing of when you eat your carbs does not affect your weight loss or muscle gain goals.