The Benefits of Intermittent Fasting

fasting

Intermittent fasting has made a big appearance in the fitness & health world and the emerging research is demonstrating interesting results. Why are people eating on this schedule and what is the purpose? Does this practice of fasting for short, repeated intervals of time heighten our fat metabolising ability? The answer seems to vary depending on the person, diet and the type of exercise.

What is intermittent fasting?

 

The theory behind this diet has roots in evolution because our ancestors did not have round the clock access to food. From this, it is reasoned that our bodies are optimized to an intermittent feeding schedule. Fasting can be done in intervals of 14-18 hours, usually done by skipping breakfast or dinner. This cycle can be repeated daily, but it is recommended that fasting should be done on a nutritious diet and to keep feeding time within a span of 6-7 hours. Other fasting methods include fasting for 2 days of the week or doing a full 24 hour fast once or twice a week.

 

What is it good for?

 

The benefits of intermittent fasting paired with exercise are being understood and researched deeply with a focus on physical health and weight loss. The concept is based on the fact that it takes your body approximately 6-8 hours to deplete its glycogen stores (stored glucose, aka sugar). When you are in a fasted state, these stores are nearly depleted, so during exercise your body will start to burn fat instead. If you are feeding constantly, those glycogen stores are never exhausted and your primary energy source will be carbohydrate-based energy (glucose), leaving the fat stores untouched. Besides being able to bust the stubborn belly fat, here are some other notable benefits to intermittent fasting:

 

  • Normalizes insulin sensitivity
    • Benefit to those with diabetes and heart conditions
  • Stabilizes ghrelin levels (the hunger hormone)
  • Lowers cholesterol levels
    • Lowers low-density lipoproteins (LDL – commonly referred to as the “bad fats”) in the body and  decreases coronary heart disease risk (atherosclerosis)
  • Keeps your body biologically young by triggering the release of human growth hormone (HGH), which promotes longevity
    • This natural release of HGH helps regulate body composition, bone and muscle growth, along with sugar and fat metabolism
  • Reduces inflammation and lessens free radical damage
    • Both of which could lead to age-related diseases and cancers
  • Exercising in a fasted state maximizes activity of catalytic enzymes (cyclic AMP & AMP kinases)
    • Enzymes that work to convert fat and glycogen into useable energy
  • Increases mitochondrial density and biogenesis
    • Efficient cells and higher energy output

 

Contraindications

 

Although an effective tool for body composition and many other remarkable benefits, intermittent fasting research unearthed some contraindications. A few studies have shown that even though fasting promotes longevity, those genes also suppress the release of estrogen. Estrogen is a hormone found at higher levels in females for reproductive purposes. There have been instances of female elite athletes that have missed menstrual cycles, who practice intermittent fasting and exercise to extreme extents. Therefore, in high intensity cases, fasting combined with elite-level training is not suited for the biological demand for a pregnancy.

Another contraindication is that the success of intermittent fasting depends heavily on the kind of food consumed. Most of feeding should be from nutritious forms of fat (avocados, eggs, etc). Healthy fats are great because they are more sustainable and give a satiated feeling for a longer period of time. It is recommended on this feeding schedule that you maintain a low-carb, high fat diet (LCHF) in order to gain the full benefits.

How the fast is broken is also of vital importance due to the heightened sensitive state the body is put in. The body feels low on energy and will want to put any of the food we consume almost immediately into storage. Therefore, what we eat is critical because if we overeat or have something of high carb and sugar value, the majority of that food will be stored as fat. Specialists suggest to initially break your fast with nutritious and easily digested food (vegetables, broths, yogurt, etc). So be careful to avoid, low nutritious, gut-filling meals when breaking the fast.

Exercising in a fasted state

 

Cardiovascular exercises (running, swimming, cycling) are commonly paired with fasting for the purpose of mobilizing fat stores to use them for energy. Although this has been proven to be an effective practice for burning fat, the breakdown of proteins is also observed. This can be futile for those who are looking to gain muscle mass, but can also be combatted by ingesting fast-digesting proteins, such as whey, after your cardio exercise.

Due to the oxidative nature of fat, it is used as fuel when your body is put into the aerobic state (energy used with oxygen). Endurance/cardiovascular exercises get your body in an aerobic state and when done in the fasted state, is optimal for burning fat. This should be considered if you are predominantly training with weights or at high-intensities that are demanding on the anaerobic system (energy used without oxygen). Anaerobic exercise should be done in the fed state, so you will have the correct sources of energy available (carbohydrates) and will perform optimally. Whichever exercise you practice, how and when you exercise should be factored in when you practice fasting.

 

Considerations

 

Evidently, intermittent fasting has positive effects on breaking down fats, insulin resistance related issues, lowering triglyceride levels in the blood, promoting longevity and even increasing the quality of your cells via mitochondrial biogenesis and other transcriptions. With all these great health benefits to fasting, there are certainly other things to consider such as the necessary diet, when and how you train and perhaps even gender. While fasting seems to offer many advantages to gaining optimal health in this modern world, always be sure to consult your trusted practitioner when making drastic lifestyle changes.  If you’re thinking of trying intermittent fasting, we recommend starting slowly by lengthening the time in between meals.  To enjoy the benefits of fasting will take some time, so pace yourself and be sure to contact us if you have questions about how to successfully implement an intermittent fasting plan.

 

References:

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Fontana, L., Meyer, T.E., Klein, S., Holloszy, J.O. Long-term calorie restriction is highly effective in reducing the risk for atherosclerosis in humans. Proc Natl Acad Sci U S A. 2004;101:6659–63.

Hansen, K., et al.. The effects of exercise on the storage and oxidation of dietary fat.Sports Med 35: 363-373, 2005.

Heilbronn, L.K., Smith, S.R., Martin, C.K., Anton, S.D., Ravussin, E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Am J Clin Nutr. 2005;81:69–73.

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Wing, R.R. Use of very-low-calorie diets in the treatment of obese persons with non-insulin-dependent diabetes mellitus. J Am Diet Assoc. 1995;95:569–72.

 

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