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Diet & Nutrition

Intermittent Fasting- How Does it Work? Is it for Me?

Dt. Dhanalakshmi

Intermittent fasting can start from 16 hours of fast and last for more than 36 hours too

Intermittent fasting is an eating style where you eat within a specific time period and fast the rest of the time. Now, fasting as a concept is not new — for centuries, people have temporarily restricted their food intake for religious reasons. Every religion in India has its own form of intermittent fasting, be it Ramadan, Paryushana, Ekadashi or Navratri. Times and traditions have underlined the multiple benefits of fasting, be it – weight loss, detoxification or enhancing vital organ function and many more. Which means intermittent fasting is not really a diet plan but a complete lifestyle change.

Intermittent fasting can start from 16 hours of fast and last for more than 36 hours too. It is not necessary to follow a method of fasting. Listen to your body, eat when you are hungry and don’t eat when you are not. That sounds so simple right? Yes, it is just as simple but, the benefits are too many.


Glucose and fat are the body’s main sources of energy. Glucose is the most easily accessible fuel source for the body. However, if glucose is not available, the body can adjust by switching to fat metabolism, without any detrimental health effects.

The process goes as follows —

So, let’s say you’ve taken our advice and incorporated intermittent fasting as part of your lifestyle. This is what’s going on in your body when –

0 hours of fasting

When you have your meals, your insulin levels are raised. This allows uptake of glucose into tissues so as to be used directly for producing energy. Excess glucose is stored as glycogen in the liver.

6-24 hours of fasting

This is when your insulin levels would have started to fall. Subsequent breakdown of the glycogen from the liver releases energy required to meet your body’s needs.

24-48 hours of fasting

These glycogen reserves last for roughly 24 hours. Post which your liver will now manufacture new glucose from amino acids through a process called as gluconeogenesis – which literally translates to ‘making new glucose’.

48-72 hours after fasting

The low insulin levels in your body stimulate the breakdown of fat for energy – this process is called lipolysis. The storage forms of fat (aka triglycerides) are broken into glycerol and 3 fatty acids. Now, this glycerol will be used for making new glucose whereas the fatty acids can be directly used as energy by your tissues – but not the brain. This crossing of the blood-brain barrier can be done by ketone bodies produced from fatty acids – which can be used by the brain.

96 hours after fasting

During this stage, approx. 75% of the energy used by the brain will be provided by the ketone bodies – which can increase to over 70-fold during fasting.

120+ hours after fasting

During this phase, the high levels of growth hormone in your body help in maintaining muscle mass and lean tissues. The energy for maintaining your metabolism is almost entirely met using free fatty acids and ketone bodies. Additionally, increased adrenalin levels in your body will prevent the decrease in metabolic rate.

One must be aware of the fact that our body has well-developed mechanisms for dealing with periods of low food availability. In a nutshell, what fasting does to the body is very simple — it switches your body’s energy reserves from burning glucose to burning fat; as soon as these glucose reserves are emptied. It’s as simple, changing your bank account from A to B because B is giving you better returns – now that’s a welcome change, isn’t it?

Types of intermittent fasting:

1.16/ 8 method:

  • The 16/8 Method involves fasting every day for 14-16 hours and restricting your daily eating window to 8-10 hours. Within the eating window, you can fit in 2 or 3 meals. Preferably have a low carb meal.
  • A general rule of thumb would be — if you finish your last meal at 8 pm and then don’t eat until 12 noon the next day, then you are fasting for 16 hours between meals. You can drink water, black or green tea without sugar, but care should be taken with people whose acidic levels are on the higher side and such people can avoid having caffeinated drinks on empty stomach.
  1. The 5:2 method:
  • This involves eating normally 5 days of the week while restricting calories to 500-600 on the rest of the two days.
  1. Eat-Stop-Eat:
  • Eat-Stop-Eat involves a 24-hour fast, either once or twice per week.
  • For example, if you finish dinner on Monday at 7 pm, and don’t eat until dinner the next day at 7 pm, then you’ve just done a full 24-hour fast. You can also fast from breakfast to breakfast, or lunch to lunch. The result is the same.
  1. Alternate day fasting:
  • Alternate-Day fasting means fasting every other day and having few hundred calories not more than 500 on the day of fasting. A full fast every other day seems rather extreme, so we wouldn’t recommend this for beginners. With this method, you will be going to bed very hungry several times per week, which is not very pleasant and probably unsustainable in the long-term.
  1. The warrior diet:
  • Basically, you fast for the whole day and feast at the night within a four hour eating window. It involves eating small amounts of raw fruits and vegetables during the day.
  1. Spontaneous meal skipping:
  • Another more natural way to do intermittent fasting is to simply skip 1 or 2 meals when you don’t feel hungry that’s just like listening to your body.

There are a lot of people getting great results with these methods.


  • Insulin levels: Blood levels of insulin drop significantly, which facilitates fat burning
  • Human growth hormone: The blood levels of growth hormone may increase as much as 5-fold. Higher levels of this hormone facilitate fat burning and muscle gain, and other benefits.
  • Cellular repair: The body induces important cellular repair processes, such as removing waste material from cells.
    Intermittent fasting works on both sides of the calorie equation. It boosts your metabolic rate (increases calories out) and reduces the amount of food you eat (reduces calories in). Lower insulin levels, higher growth hormone levels and increased amounts of adrenaline all increase the breakdown of body fat and facilitate its use for energy.
    Intermittent fasting has been shown to have major benefits for insulin resistance and lead to an impressive reduction in blood sugar levels. Fasting blood sugar has been reduced by 3-6%, while fasting insulin has been reduced by 20-31%.
    Several studies show that intermittent fasting may enhance the body’s resistance to oxidative stress. Additionally, it can also help fight inflammation, another key driver of all sorts of common diseases.
    Intermittent fasting has been shown to improve numerous different risk factors, including blood pressure, total and LDL cholesterol, blood triglycerides, inflammatory markers, and blood sugar levels.
    When we fast, the cells in the body initiate a cellular “waste removal” process called autophagy. This involves the cells breaking down and metabolizing broken and dysfunctional proteins that build up inside cells over time. Increased autophagy may provide protection against several diseases, including cancer and Alzheimer’s disease.
    Fasting has been shown to have several beneficial effects on metabolism that may lead to reduced risk of cancer.

Who should NOT fast?

You should not do intermittent fasting if you are:

  • Underweight (BMI < 18.5) or have an eating disorder like anorexia.
  • Pregnant – you need extra nutrients for your child.
  • Breastfeeding – you need extra nutrients for your child.
  • A child under 18 – you need extra nutrients to grow.

You can probably fast, but may need medical supervision, under these conditions:

  • If you have diabetes mellitus – type 1 or type 2
  • If you take prescription medication
  • If you have gout or high uric acid
  • If you have any serious medical conditions, such as liver disease, kidney disease, or heart disease

If you need further help in planning out your diet or have any more questions on the benefits of intermittent fasting for your body, you should definitely consult with a nutritionist immediately who will then help you chalk out a diet plan suited to your needs after knowing your medical history. The mfine app gives you access to the city’s best nutritionists and dietitians for an online consultation, the minute you need to.

The email ID needs to be in the form of xxx@yyy.zzz

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