Intermittent Fasting (IF) has gained significant attention as a popular dietary strategy with potential health benefits beyond weight management. It involves alternating cycles of eating and fasting, leveraging the body’s natural metabolic processes. Several different types of intermittent fasting exist, each with its approach and potential benefits.
Intermittent Fasting Methods
16/8 Method
This is one of the most common forms of intermittent fasting. It involves fasting for 16 hours daily and restricting eating to an 8-hour window. For example, you might eat between 12 PM and 8 PM and fast from 8 PM to 12 PM the next day. This method is relatively easy to incorporate into daily life, as it doesn’t require skipping entire days of eating.
5:2 Diet
In this approach, you usually eat five days a week and significantly restrict calorie intake (usually around 500-600 calories) on the remaining two non-consecutive days. The fasting days can be chosen based on personal preference, and the reduced calorie intake promotes a calorie deficit over the week, potentially aiding weight loss.
Eat-Stop-Eat
This method involves fasting for 24 hours once or twice a week. For instance, you might have dinner at 7 PM and then not eat again until 7 PM the following day. While this approach can lead to extended fasting periods, it might be challenging for some individuals to go without food for a full day.
Alternate-Day Fasting
This method alternates between regular eating and fasting days or significantly reduced calorie intake. Some variations allow around 500 calories on fasting days, while others involve complete fasting. This approach can be practical for weight loss but might be harder to sustain over the long term.
Warrior Diet
The Warrior Diet involves a 20-hour fasting period followed by a 4-hour eating window in the evening. Small amounts of raw fruits, vegetables, and protein sources are allowed during the fasting window. Ancient warrior cultures inspire this method and aim to align eating patterns with natural circadian rhythms.
24-Hour Fast
Like Eat-Stop-Eat, this method involves fasting for 24 hours but can be done more frequently than once or twice a week. Some individuals opt for a 24-hour fast once every few days or even daily.
Extended Fasting
Fasting for extended periods, usually 48 to 72 hours or even longer. Extended fasting should be approached cautiously and under medical supervision due to the potential for nutrient deficiencies and other health risks.
How It Affects Your Cells and Hormones
As good as intermittent fasting sounds, it’s important to note that current research is in its preliminary phases. A substantial portion of the studies conducted were of limited scale, had short durations, or were carried out on animal subjects. Numerous inquiries remain unresolved, underscoring the necessity for more robust and comprehensive human studies to address these uncertainties.
During fasting, various physiological transformations occur at your body’s cellular and molecular levels. Hormone levels undergo modifications to enhance the accessibility of stored body fat, facilitating its utilisation. Concurrently, cellular repair mechanisms are initiated, accompanied by alterations in gene expression.
The following are some of the physiological shifts that transpire within your body during fasting:
Human Growth Hormone (HGH)
Levels of growth hormone experience a substantial surge, escalating by up to fivefold. This surge in HGH brings about advantages such as promoting fat reduction and facilitating muscle growth (4Trusted Source, 5Trusted Source, 6Trusted Source, 7Trusted Source).
Insulin
Fasting improves insulin sensitivity, leading to a significant decline in insulin levels. Reduced insulin levels increase accessibility to stored body fat (8Trusted Source).
Cellular Restoration
Fasting triggers intricate cellular repair mechanisms, including the induction of autophagy. This process involves breaking down and eliminating aged and dysfunctional proteins that accumulate within cells (9Trusted Source, 10Trusted Source).
Gene Expression
Fasting induces modifications in the functioning of genes associated with longevity and safeguarding against diseases (11Trusted Source, 12Trusted Source).
These fluctuations in hormone concentrations, cellular functionality, and gene activity collectively underlie the health benefits associated with intermittent fasting.
Summary
During fasting periods, there is an elevation in human growth hormone levels while insulin levels decrease. Additionally, alterations occur in gene expression within the body’s cells alongside the initiation of vital cellular repair mechanisms.
A Powerful Weight Loss Tool
Weight reduction is the primary incentive for individuals embarking on intermittent fasting. By prompting a reduction in meal frequency, intermittent fasting naturally induces a decrease in overall calorie consumption. Furthermore, this dietary approach orchestrates changes in hormone levels that facilitate shedding excess weight.
Notably, in conjunction with diminishing insulin levels and augmenting growth hormone concentrations, intermittent fasting amplifies the release of norepinephrine (noradrenaline), a hormone that ignites the fat-burning process. These shifts in hormonal dynamics can potentially elevate your metabolic rate by a range of 3.6% to 14% during short-term fasting.
The potency of intermittent fasting in weight management derives from its dual impact on the caloric equation – reducing intake while enhancing expenditure. Compelling research affirms its efficacy as a formidable tool for weight loss. A comprehensive review from 2014 disclosed that this dietary pattern yielded weight reduction of 3% to 8% over 3 to 24 weeks, which is a significant amount compared to most weight loss studies.
The same study reported waist circumference reductions of 4% to 7%, indicating a noteworthy decline in visceral fat – the dangerous adipose tissue enveloping vital organs, contributing to health complications.
In parallel, a study conducted in 2011 unveiled that intermittent fasting resulted in comparatively lesser muscle loss than the conventional mode of continuous calorie restriction.
However, remember that the main reason for its success is that intermittent fasting helps you eat fewer calories overall. You may not lose weight if you binge and eat massive amounts during your eating periods.
Health Benefits
There have been many studies on intermittent fasting in both animals and humans. These studies have shown that it can have powerful benefits for weight control and your body and brain health. It may even help you live longer.
Here are the main health benefits of intermittent fasting:
Weight loss
As mentioned above, intermittent fasting can help you lose weight and belly fat without consciously restricting calories.
Insulin resistance
Intermittent fasting can reduce insulin resistance, lowering blood sugar by 3–6% and fasting insulin levels by 20–31%, which should protect against type 2 diabetes.
Inflammation
Some studies show reductions in markers of inflammation, a key driver of many chronic diseases.
Heart Health
Intermittent fasting may reduce “bad” LDL cholesterol, blood triglycerides, inflammatory markers, blood sugar and insulin resistance — all risk factors for heart disease.
Cancer
Animal studies suggest intermittent fasting may prevent cancer.
Brain Health
Intermittent fasting increases the brain hormone BDNF and may aid the growth of new nerve cells. It may also protect against Alzheimer’s disease.
Anti-ageing
Intermittent fasting can extend the lifespan of rats. Studies showed that fasted rats lived 36–83% longer.
In Summary
As good as intermittent fasting sounds, it’s important to note that current research is in its preliminary phases. A substantial portion of the studies conducted were of limited scale, had short durations, or were carried out on animal subjects. Numerous inquiries remain unresolved, underscoring the necessity for more robust and comprehensive human studies to address these uncertainties.
