How can I increase fat oxidation?

From the Guidelines

To increase fat oxidation, incorporate a combination of regular aerobic exercise, dietary changes, and lifestyle modifications, as evidenced by the most recent and highest quality study 1.

Key Recommendations

• Incorporate regular aerobic exercise at moderate intensity (60-70% of maximum heart rate) for at least 30-45 minutes, 3-5 times weekly, as suggested by 1.
• Consider adding high-intensity interval training (HIIT) 1-2 times weekly, alternating between intense effort (30-60 seconds) and recovery periods.
• Dietary changes are equally important: reduce carbohydrate intake, especially refined carbs and sugars, while increasing protein (1.6-2.2g per kg of body weight daily) and healthy fats, such as monounsaturated fats (MUFAs) and polyunsaturated fats (PUFAs), as recommended by 1 and 1.
• Intermittent fasting methods like 16:8 (16 hours fasting, 8-hour eating window) can enhance fat oxidation by lowering insulin levels and increasing fat-burning hormones.
• Stay well-hydrated and ensure adequate sleep (7-9 hours nightly) as sleep deprivation disrupts metabolism.
• Cold exposure through cold showers or ice baths may activate brown fat and increase metabolic rate.

Rationale

The most recent and highest quality study 1 suggests that a Mediterranean diet, which is rich in MUFAs and PUFAs, can improve fat oxidation and reduce liver fat content. Additionally, reducing carbohydrate intake and increasing protein and healthy fat intake can enhance fat oxidation, as evidenced by 1 and 1. Regular aerobic exercise and HIIT can also improve mitochondrial function, increase metabolic flexibility, and enhance hormone sensitivity, leading to increased fat oxidation.

Important Considerations

• The effects of dietary saturated fat on health must consider the important role of carbohydrate intake and the underlying degree of insulin resistance, as highlighted by 1.
• The ratio of ω6 to ω3 fats plays an important role in increasing the prevalence of chronic metabolic diseases, and a balanced intake of these fats is essential, as suggested by 1 and 1.
• Individual responses to different diets and exercise programs may vary, and it is essential to consult with a healthcare professional before making any significant changes to your lifestyle.

From the Research

Factors Affecting Fat Oxidation

• Exercise intensity and duration are important determinants of fat oxidation, with maximal rates of fat oxidation reached at intensities between 59% and 64% of maximum oxygen consumption in trained individuals and between 47% and 52% of maximum oxygen consumption in the general population 2
• The mode of exercise can also affect fat oxidation, with fat oxidation being higher during running than cycling 2
• Ingestion of carbohydrate in the hours before or on commencement of exercise reduces the rate of fat oxidation significantly compared with fasted conditions, whereas fasting longer than 6 h optimizes fat oxidation 2
• Fat oxidation rates have been shown to decrease after ingestion of high-fat diets, partly as a result of decreased glycogen stores and partly because of adaptations at the muscle level 2

Effects of High-Intensity Interval Training (HIIT) on Fat Oxidation

• Completion of HIIT has been reported to increase whole-body fat oxidation (FOx) in different populations 3
• An explanation for this increase in FOx is primarily peripheral adaptations via improvements in mitochondrial content and function 3
• Significant increases in β-HAD, citrate synthase, fatty acid binding protein, or FAT/CD36 are likely responsible for the greater FOx seen in these studies 3
• Engaging in HIIT can improve fat oxidation, with larger effects expected for longer training regimens and individuals with overweight/obesity 4

Role of Physical Activity in Fat Oxidation

• Concurrent physical activity increases fat oxidation during the shift to a high-fat diet 5
• The 24-h respiratory quotient decreased more rapidly and to a greater extent under conditions of increased energy expenditure 5
• Cumulative carbohydrate and protein balances were greater under conditions of increased physical activity, whereas cumulative fat balance was greater under sedentary conditions 5

Exercise Guidelines for Optimizing Fat Oxidation

• Exercise training performed at maximal fat oxidation (FATmax) is an efficient non-pharmacological approach for the management of obesity and its related cardio-metabolic disorders 6
• A heart rate of 61-66% HRpeak should be recommended to patients with >35% body fat, while a heart rate of 57-64% HRpeak should be recommended to patients with body fat <35% 6
• Training volume must be higher in adults to achieve a similar fat oxidation compared with adolescents, whereas exercising on a treadmill requires a lower training volume to achieve significant fat oxidation in comparison with stationary cycling 6