Caffeine, a compound found in foods like coffee, tea, chocolate, and energy drinks, is not only famous for its ability to stimulate and keep us alert. It is also considered an ally in the realm of physical performance, playing a key role in energy metabolism and fat oxidation during exercise.
Understanding Energy Utilization in the Body
Before delving into the effects of caffeine, it’s essential to understand where and how the body derives energy.
In essence, muscle fiber cells extract energy from carbohydrates, fats, and proteins, converting them all into one of the cell’s “currency”: adenosine triphosphate (ATP). The energy density of different “natural fuels” varies, with fats providing the most energy per gram of weight.
The body tends towards maximum efficiency. As humans can store more fat than carbohydrates, the body will prioritize the use of fats for energy whenever possible.
However, there’s a catch: since fats are large and complex molecules, breaking them down to obtain ATP is slower than with other substrates. Therefore, when a large amount of energy is needed in a short period, the body prioritizes the use of carbohydrates, which can be broken down more rapidly to meet immediate energy demands.
However, relying on carbohydrates has a significant limitation. Their reserves in the body are limited, especially in the form of glycogen in muscles and the liver (approximately providing energy for about 60 minutes of moderate-intensity work if not supplemented during exercise).
During prolonged or high-intensity exercises, such as marathons or cycling, the rapid depletion of reserves can lead to fatigue, decreased physical and mental performance, and sometimes, muscle soreness and exhaustion.
Additionally, since the brain requires glucose constantly, low availability can affect concentration and the ability to make critical decisions during physical activity.
Caffeine’s Role in Fat Utilization
Beyond its well-known stimulating effect on the central nervous system, caffeine arouses particular interest for its ability to positively influence fat oxidation during exercise. This means that, under the influence of caffeine, our bodies tend to use more fatty acids as a source of energy during low to moderate exercise intensities, thereby reducing the rate of carbohydrate or muscle and liver glycogen oxidation.
This mechanism is particularly advantageous in sports disciplines such as cycling, marathons, or triathlons, where preserving glycogen means athletes can maintain a high level of performance for longer. Additionally, it has been discovered that caffeine contributes to conserving glycogen reserves in muscles, delaying exhaustion and thus facilitating an improvement in performance.
Does it Necessarily Lead to Weight Loss?
After consuming a cup of coffee, this dark brew begins its journey through the stomach, then travels through the bloodstream to the brain, where it has effects that help us stay alert. But beyond keeping us awake, coffee has physiological effects related to the utilization of energy substrates during physical exercise.
The first effect is linked to adrenaline, the hormone that prepares us to run faster or jump higher in “fight or flight” situations. Under the influence of caffeine, adrenaline activates lipases (enzymes) responsible for breaking down stored fats (triglycerides), converting them into readily available energy for muscles. By increasing the concentration of fatty acids in the blood, the use of fats as a source of energy increases.
At the same time, caffeine acts as a blocker of cellular adenosine receptors, allowing us to delay the sensation of fatigue. This helps to maintain high energy levels, allowing us to exercise for longer before feeling tired. Consequently, we utilize fats more efficiently as a fuel source.
And does this increase in fat oxidation imply weight loss? Not necessarily. For weight loss to occur, there must be a negative energy deficit (caloric intake lower than calories expended). Moreover, it’s a complex process influenced by many variables, including hormones, psychological factors, and lifestyle aspects.
Caffeine and Fat Oxidation
Various studies confirm that caffeine increases fat oxidation in different populations, including both men and women. The effective dose usually starts from 3 mg/kg of body weight, although individual sensitivity may vary. This underscores the importance of personalizing the dose to maximize metabolic benefits without compromising overall well-being.
Interestingly, recent studies indicate that caffeine intake improves fat oxidation both in the morning and in the afternoon, with just 3 mg/kg of body weight. But here’s the surprising part: it turns out that even believing that we are consuming caffeine can boost fat oxidation almost as much as actually consuming it. This teaches us something fascinating, not only about the power of caffeine but also about how our expectations can enhance our athletic performance.
Moderation is Key
All indications suggest that caffeine emerges as a valuable tool for those looking to optimize fat oxidation and improve athletic performance. It acts not only as a potent stimulant but also as an effective promoter of using fats as an energy source.
However, despite its benefits in sports performance, it is crucial to handle caffeine consumption with care. Excessive intake can trigger side effects such as nervousness, insomnia, and an increase in blood pressure. Success lies in balance and personalization of consumption, always considering individual responses and needs, and adjusting the dose to find the perfect balance that enhances performance without compromising health.
Moreover, it’s only an extra aid. The starting point should be proper training, healthy eating according to the goal, adequate rest, and maintaining a healthy mental state.
Authors:
- Alejandro Muñoz – Professor and Researcher in Physical Activity and Sports Sciences, Francisco de Vitoria University.
- David Varillas Delgado – Professor of Physical Activity and Sports Sciences (CAFyD) and Coordinator of the “Elite Athletes and High Performance” Research Group, Francisco de Vitoria University.
- Jorge Gutiérrez Hellín – Professor/Researcher/Disseminator in the field of Health and Sports Performance.
- Millán Aguilar Navarro – Professor of Physical Activity and Sports Sciences (CAFyD) and Coordinator of the “Doping in Sports” Research Group, Francisco de Vitoria University.
