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What does fasting mean?

Fasting, in its various forms, has gained a lot of attention for its potential health benefits. Fasting is described as abstaining from particular foods, drinks or both for specific periods of time.

For example, in recent years, intermittent fasting has emerged as a popular dietary approach, characterised by alternating periods of eating and fasting. This strategy comes in various forms, including the 16/8 method, where individuals fast for 16 hours and consume meals within an 8-hour window, or the alternate-day fasting regimen, involving alternating days of normal eating and fasting. 

What is caffeine?

Caffeine is a natural stimulant, affecting multiple systems in the body including the central nervous system, respiratory system, digestive system and cardiovascular system. As a result caffeine is found to increase alertness, elevate mood, reduce tiredness, as well as reduce appetite and increase fat metabolism. 

How does caffeine affect weight loss?

Studies indicate that caffeine can facilitate weight loss by functioning as a fat-burning agent. Research reveals that caffeine enhances the rate of fat oxidation (the mechanism responsible for breaking down fat for energy) during physical activity, contributing to sustained weight loss. Furthermore, caffeine has been observed to mildly elevate the body’s resting metabolism, thereby aiding weight loss even during periods of rest (Harpaz et al, 2017).

A 2022 systemic review and meta-analysis by Conger et al explored the question: “Does Caffeine Increase Fat Metabolism?”, here’s what the results show:

  1. Caffeine amplifies fat metabolism: Caffeine emerges as an enhancer of fat metabolism, yielding a significant albeit modest effect size mostly independent of individual factors including gender, fitness level, and caffeine dosage. (Conger et al, 2022) . 
  2. Rest vs. Exercise: While the impact of caffeine on fat metabolism is evident under both rest and exercise conditions, its efficacy appears more pronounced during rest. 
  3. Optimal dosage: Aim for doses greater than 3.0mg/kg of body weight, ideally ranging between 3.1 to 7.0mg/kg, to maximise caffeine’s metabolic effects. Usually between 200mg to 400mg of caffeine per day, which equates to two to four regular cups of coffee.
  4. Strategic timing: Consume caffeine 30 to 75 minutes prior to exercise for peak effectiveness in promoting fat oxidation. NB be mindful of how when you consume caffeine in relation to your bedtime!

This study found that caffeine does increase fat metabolism regardless of individual factors and this is supported by another study by Kim et al. However Kim concludes that while caffeine increases fat metabolism in all individuals, there is a greater effect on individuals within a normal weight range (Kim et al, 2017).

Overall, relying solely on caffeine for weight loss is not advisable, but integrating it into a balanced lifestyle can yield modest benefits. By adding caffeine to your daily regimen, you may experience a slight boost in metabolism, reduced appetite, and enhanced workout performance. However, sustainable weight loss requires more than just caffeine consumption; it necessitates a holistic approach that includes regular exercise, a nutritious diet, proper hydration and sufficient sleep.

When including caffeine in your weight loss strategy, monitor your body’s response and make adjustments as needed. Aim for a daily intake of 200-400 milligrams of caffeine, equivalent to approximately two to four cups of coffee. Opt for high-quality caffeine sources and avoid excessive consumption to mitigate potential adverse effects.

In summary, moderation is key when it comes to caffeine consumption. Incorporating it alongside other healthy habits can contribute to your weight loss journey and help you maintain a healthy weight in the long term.


Collado-Mateo, D., Lavín-Pérez, A. M., Merellano-Navarro, E., & Coso, J. D. (2020). Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis. Nutrients, 12(12), 3603. Conger, S.

A., Tuthill, L. M., & Millard-Stafford, M. L. (2023). Does Caffeine Increase Fat Metabolism? A Systematic Review and Meta-Analysis. International Journal of Sport Nutrition and Exercise Metabolism, 33(2), 112-120. Retrieved Apr 3, 2024, from

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