What are the effects of fasted cardio?
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Effects of Fasted Cardio: A Comprehensive Review
Introduction to Fasted Cardio
Fasted cardio, the practice of performing cardiovascular exercise on an empty stomach, has gained popularity for its potential benefits on weight loss and cardiometabolic health. This article synthesizes findings from multiple studies to provide a clear understanding of the effects of fasted cardio.
Weight Loss and Body Composition
Impact on Weight and Fat Mass
Several studies have shown that intermittent fasting (IF), which often includes periods of fasted exercise, can lead to significant weight loss and reductions in fat mass. A systematic review and meta-analysis found that IF reduced body weight by an average of 1.78 kg and fat mass by 1.26 kg compared to control diets. Another study confirmed that both IF and continuous energy restriction (CER) resulted in similar weight loss, indicating that the timing of food intake might not significantly alter weight loss outcomes.
Visceral Fat Reduction
Research indicates that IF combined with exercise can effectively reduce visceral fat. A study comparing IF, sprint interval training (SIT), and their combination found that both IF and the combined IF/SIT regimen significantly decreased visceral fat compared to exercise alone. This suggests that fasted cardio may be particularly effective in targeting abdominal fat.
Cardiometabolic Health
Blood Lipid Levels
Fasted cardio has been shown to improve blood lipid profiles. Studies have reported reductions in total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides with IF regimens . These improvements are crucial for reducing the risk of cardiovascular diseases.
Blood Pressure and Insulin Sensitivity
Intermittent fasting, including fasted cardio, has been associated with reductions in both systolic and diastolic blood pressure . Additionally, improvements in insulin sensitivity have been observed, which are beneficial for managing and preventing type 2 diabetes .
Hormonal Responses and Energy Metabolism
Hormonal Changes
Fasted cardio influences various hormonal responses. For instance, a study found that exercise performed in a fasted state led to lower heart rates and respiratory quotients, indicating a shift towards fat oxidation. However, changes in hormones like leptin and ghrelin were not significant, suggesting that other mechanisms might be at play in the cardiovascular responses to fasted exercise.
Energy Expenditure and Substrate Oxidation
Fasted cardio may alter energy metabolism by increasing fat oxidation. Research indicates that IF regimens can enhance protein and fat oxidation compared to continuous caloric restriction. This shift in substrate utilization can be beneficial for improving body composition and metabolic health.
Gut Microbiota and Inflammation
Gut Health
Intermittent fasting, including fasted cardio, has been shown to positively affect gut microbiota. A study on metabolic syndrome patients found that IF significantly altered gut microbiota composition, increased the production of short-chain fatty acids (SCFAs), and decreased circulating lipopolysaccharides (LPS), which are markers of inflammation. These changes are associated with improved cardiometabolic risk factors.
Inflammatory Markers
Fasted cardio can also reduce oxidative stress and modulate inflammatory cytokines. This reduction in inflammation is beneficial for overall cardiovascular health and can help mitigate the risk of chronic diseases.
Conclusion
Fasted cardio, as part of intermittent fasting regimens, offers several benefits for weight loss, body composition, and cardiometabolic health. It improves blood lipid profiles, reduces blood pressure, enhances insulin sensitivity, and positively affects gut health and inflammation. While more research is needed to fully understand the long-term effects, current evidence supports the inclusion of fasted cardio in health and fitness routines for its potential benefits.
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