Carbohydrate backloading is a relatively new nutrition recommendation that opposes common dietary assumptions.

Most people tend to avoid carbohydrates later in the day, especially before bed, due to the fact that they think it will be more easily converted to body fat whilst inactive.

Carbohydrate backloading aims to throw this idea out the window, and actually recommends that people do the exact opposite!

What Is Carb Backloading?

Carbohydrate backloading is the term given for a diet that delays the intake of carbohydrates until later in the day – usually starting in the evening.

It does not just mention that you “can” eat carbohydrates at night, it specifically states to “only” eat carbohydrates at night.

This nutritional concept was first introduced by an American training and nutrition consultant called John Kiefer, who has since published a book named (surprise surprise) “Carb Backloading”.

How Do You “Carb Backload”?

The main principles of the diet are:

• Shift calorie consumption until later in the day. This should include a light meal in the morning and afternoon which are both low or absent in carbohydrate, followed by a high-carbohydrate calorie-dense meal just before bed. If people prefer, and especially they are looking to lose body fat, breakfast can be skipped completely.
• Exercise training should take place before the main meal in the evening is consumed. The ideal time to train on this diet is around 4-6pm.
• After the training session is finished, carbohydrate-based foods can be ingested until bed.

What Are the Supposed Benefits of Carbohydrate Backloading?

Carbohydrate loading advocates claim that the nutrient timing method laid out is based around manipulating and improving cellular, hormonal, and biological functions within the body.

Most importantly, the reason for delaying carbohydrate intake until later in the day is to limit the release of insulin in the body during the morning and afternoon.

Insulin is a hormone that signals cells to absorb and store nutrients, potentially as body fat, whilst inhibiting the release of fat stores from the cell for energy use. Considering this, it is theorized to increase fat mobilization and body composition.

In addition, an excess of insulin secretion is a key reason why people become insulin resistant and develop diabetes, as they become unable to absorb glucose into cells.

The theory also states that by incorporating resistance training in the late afternoon this will increase insulin sensitivity in muscle tissue (cells ability to uptake carbohydrates) but not fat tissue.

Hypothetically, this allows for the body to utilize the nutrients for muscle repair and rebuilding without necessarily storing any additional body fat.

The biological mechanism behind this is in relation to an increased number and activity of glucose transporters in the muscle cell after an exercise session, which will allow the cell to be more inclined to bringing nutrients into the cell.

What Does The Science Say About Carb Backloading?

There are a tonne of recent studies that suggest meal timing and daily eating patterns are crucial for preventing metabolic diseases, and play a pivotal role in the “circadian rhythms” of metabolism (the 24 hour cycle) [1].

The specific benefits are as follows:

It May Aid Weight Loss

The first benefits were found in animal studies, with rats that consumed carbohydrates in the evening after exercise having significantly less inflammation and lower body-weights [6].

Experts speculated that the main benefit of carbohydrate backloading is the effects it has on the leptin hormone. This hormone is also known as the “satiety hormone”, which sends signals from fat tissue to the brain to reduce hunger.

This is based on studies that have described a daily pattern of leptin secretion where it is less likely to be secreted in response to a meal during the day (around 8am-4pm) as opposed to throughout the evening (around 4pm-1am) [7].

Therefore, it is speculated that meals eaten in the evening are more likely to cause a feeling of fullness and satisfaction, and thus lowering daily calorie intake.

These findings have also been replicated in human research, as eating most of one’s daily carbohydrate intake at dinner, in the context of a calorie-restricted diet, has shown to cause more pronounced weight loss, reduced cravings, and improved health markers [5].

The same benefits to weight loss can even be seen in the real-world by Muslim populations during Ramadan – fasting during the day and consuming a carbohydrate-dense meal before bed [8].

It May Improve Glycemic Control

The ability to control blood sugar levels and uptake glucose into skeletal muscle is important to maintain physiologically normal blood sugar levels throughout the day and avoid the health consequences of hyperinsulinemia [9].

There is research indicating that glycemic control – the regulation of blood sugar levels – is significantly improved when carbohydrates are mainly eaten at dinner, with prior meals being predominantly based on protein and dietary fat [10].

This is because identical meals can result in vastly different blood sugar level responses, dependent on the time of day the meal is eaten.

Some research suggests that, in healthy adults, consuming carbohydrates in the evening causes a reduced blood glucose and insulin response compared to in the morning [11] [12].

However, although this limited research is often mentioned by proponents of carbohydrate backloading, most of the science actually suggests that there is a reduced glucose tolerance in the evening. This is due to decreased insulin sensitivity, elevated glucose production in the liver, increased cortisol levels (stress hormone), and decreased β cell function as the day progresses [14].

However, the relevance of this research in regards to carbohydrate backloading may be negligible when considering that carbohydrates are being consumed post-exercise when insulin sensitivity is purposefully increased.

In theory, this provides an excellent “sink” for the increased carbohydrate intake, and may offset and counterbalance the potential reductions in glucose metabolism in the evening [16].

It Partly Replicates Intermittent Fasting

Intermittent fasting is a nutritional protocol whereby people fast for 16 hours a day and then give themselves 8 hour eating windows.

One of the benefits of such a schedule is the effects on improving appetite suppression and indirectly reducing calorie intake – hence why it is so effective for initiating weight loss [17].

The other major benefits of intermittent fasting are:

• Improvements in glycemic control and insulin sensitivity as a result of the reduced glucose metabolism and increased fat metabolism. In other words, the body becomes less reliant on carbohydrate, and more likely to use fatty acids as a fuel source [18] [19].
• Anti-aging benefits from the increased expression of enzymes that contribute to cellular regulation and protect cells from the damaging effects of free radicals. Other cellular adaptations involve lower inflammation, DNA repair, and autophagy – a regulated mechanism of a cell that removes the unnecessary components [20].

Carbohydrate backloading can be viewed as an alternative form of intermittent fasting. Although it allows food to be consumed in the daytime, it follows the same principle of carbohydrate restriction outside of set eating windows.

For this reason, despite not being able to replicate the benefits of intermittent fasting, it may create similar improvements in regards to glycemic control. This is because the benefits to glycemic control during intermittent fasting are predominantly due to the avoidance of their intake for the majority of the day, which carbohydrate backloading is able to replicate.

Therefore, carbohydrate backloading may be an alternative to people that do not want to go to the “extremes” of intermittent fasting whilst still gaining some of the benefits.

Conclusion

Carbohydrate backloading is a diet whereby carbohydrates are only eaten in the evening after a workout, because this is the time where insulin is increased to a lesser extent after a meal.

This is theorized to prevent body fat gain due to the reduced insulin secretion, often touted as a harmful “fat-storing hormone”.

The research behind this concept is somewhat limited and inconclusive. It appears to have benefits for fat loss and glycemic control, however this may just be due to a lower food intake throughout the day as opposed to a direct benefit of only eating in the evening.

There is also a chance it may partly replicate some of the benefits of intermittent fasting, but this needs to be tested in future research.