Intermittent Fasting for Weight Loss

Intermittent fasting has been quite popular these days to lose weight, improve health and to cherish the fact of living longer. We are here to know what it is, its history, methods, beneficial results and to know about any possible side effects.

What Is Intermittent Fasting (IF)?

intermittent fasting question
Courtesy: Photo by Tim Wildsmith

At first instance, Intermittent Fasting (IF) gives the impression of dieting but it is not. It is a kind of fasting where you either eat a little or not eat at all for a specific time. Unlike general dieting, it doesn’t restrict in choosing what you want to eat.

We know fasting is an ancient tradition; over centuries its been practiced by many cultures and religions, including Buddhism, Hinduism, Islam, Judaism, Christianity. However, the therapeutic intermittent fasting for the treatment of obesity was first investigated since at least in the year 1915, and became a renewed interesting topic in the medical community in the 1960s after the publication of ‘enthusiastic report’ by Blood and his fellow colleagues. A type of periodic fasting (known as 5:2 diet) was introduced by Michelle Harvie and Mark Mattson which was popularised in the UK and Australia around 2012 by Michael Mosley. As of 2019, Intermittent fasting has grown into a big phenomenon attracting celebrity endorsement and public interest, worldwide.

Benefits of Intermittent Fasting:

More people are joining the Intermittent fasting trend due to its weight loss results. Saying that, IF has numerous other benefits which are listed below based on research findings:

  • Give our body a break: Going into fasting mode gives our vital organs, hormones and certain hormones a ‘break’.
  • Cellular repair: While fasting our body goes into cellular repair mode such as removing waste material from cells and rejuvenating the tissues.
  • Gene expression: Beneficial changes take place among several genes and molecules, which protect against certain ailments and diseases in the long run.
  • Boost Human Growth Hormone: The blood levels of human growth hormone (HGH) spikes dramatically which helps in gaining new muscle tissues and burning body fat. 
  • Insulin balance: Insulin level drops which improve insulin sensitivity. Too much insulin secretion leads to development of metabolic disorder kickstarting prediabetic, so IF lowers the risk of developing type 2 diabetic.
  • Lowers oxidative stress and inflammation throughout the body. We know inflammation is the root cause of many chronic diseases.
  • Good for cardiac health: Due to beneficial impact on blood sugar, blood pressure and triglycerides levels in  blood while reducing inflammation contributes to synergistic effect on improving heart health.
  • Brain health: Proper insulin metabolism and other factors like less oxidative stress and inflammation with Intermittent fasting helps memory along with overall brain health.
  • Longevity: Studies in rodents have shown intermittent fasting extends lifespan by around 13%. Meta analysis on human studies is still pending to look into this area.
  • May help prevent Alzheimer’s disease and development of cancers. 

How Intermittent Helps in Weight Loss?

To understand how Intermittent fasting helps us losing weight, we need to understand the four transition state, that our body goes through when we fast:

1. Absorptive stage: After a meal our body fat storage goes into an active mode for about four hours when the primary source of fuel is glucose to carry out body functions.

2. Post absorptive stage: Glycogen (glucose reserves in liver) is released as a fuel source at this state which can last up to 18 hours.

3. The fasted stage: Continued fasting, 12 to 20 hours, transition progress to other fuel reserves like fat, lactic acid and alanine as fuel source in between 12 to 20 hours as glycogen reserves in the liver started depleting.

4. Metabolic Switch: This is the end stage when fat storage and lipid synthesis mobilize into the free fatty acid-derived ketone to supply energy transforming our body into a fat burning furnace.

Besides production of abundant ketone bodies (KB) from the free fatty acids, higher HGH levels, lower insulin levels and finally the increased amount of noradrenaline hormone  creates a domino effect on breaking down the body fats rapidly with overall increased energy.

Besides burning excess body fats, fasting helps to detox our vital organs enabling our systems to work better and efficiently to help with weight loss while minimising health risks and improving our life expectancy.

Read More: The Hidden Dangers of Excess Belly Fat You Should Know

Types of Intermittent Fasting:

There are mainly three types of intermittent fasting:

1. Time restricted fasting: This involves only a certain number of hours of fasting each day along with a consistent pattern of caloric intake. The hours of fasting can last 8 hours, 12 hours, 16 hours or even 20 hours with the remaining timing window for feeding. For example, it can be a 16:8 diet which is 16 hours of fasting cycled by 8 hours of non-fasting hours.

2. Alternate-day fasting: In this method, you fast one day (24 hours) and take minimal food consisting of 1/4th of the usual energy requirement, and then followed by a non-fasting day (24 hours).

3. Periodic fasting: This one involves period of consecutive fasting of more than 24 hours; for example the 5:2 diet where for five days (per week) you eat normally and without thinking about caloric restrictions, and on the remaining two days you just reduce your calorie intake to 25% of your daily needs, which should be approximately 500 to 700 calories.

So which one is the popular method? Intermittent fasting 16/8 method is the most popular one as many people find it to be the simplest and easier to stick to. On this 16:8 diet, you do 16 hours of fasting each day taking nothing but simply plain water or tea, coffee. Remaining 8 hour you take your snacks and meals. With this method one usually starts fasting at night skipping your dinner and then skipping your breakfast waking up in the morning and then taking your meal during the mid-day. Many people have proven to lose weight drastically with this method while making sure to have only sugar free or less sugar based beverages during the fasting phase.

For example this reddit user (Suesiesunshine) gave her comments about the 16/8 fasting method. While writing this review her age was 49:

‘’I’ve been doing that for several months and I believe that it’s helped reset my relationship with food to a much more healthy perspective. I was so food obsessed before! You think I was about to starve to death even though I need to lose a few pounds.

In the morning I have a cup of tea with a scoop of powdered MCT oil for energy and that keeps me full. I generally get hungry around 11 AM or noon and then break my fast and eat until seven or 8 PM. I find that it has made it much easier for me to eat the right amount of calories without feeling deprived. I do a “lazy keto” type diet with a target of 20 to 30 net carbs per day.

I’ve had several people ask about whether I have enough energy to work out, and I absolutely do! You just need to get through a couple of days to get all of the carbs out of your system and get your body into using ketones for energy. It’s worked great for me and it was an effortless way to lose about 20 to 30 pounds.’’

As you can see the above review is quite encouraging and you shall find more comments about 16:8 fasting method here:

This 16/8 is most popular as you can include your sleeping time easily in your 16 hours of not eating phase. And don’t have to go through the hassle of taking time having breakfast in the morning while preparing yourself for going to work.

Research Findings:

Most studies on humans have observed weight loss ranging in between 2.5 to 9.9%.

For time-restricted eating, like 16/8 or 20/4 IF, the ratio of weight loss is 3:1 for body fat loss and lean mass. (source)

Alternate-day fasting would be better for people who would worry about losing lean mass as it doesn’t affect body mass.

Also this fasting method is really good for overweight people with metabolic syndrome as it improves metabolism and cardiac health. (source)

Any Side Effects of Intermittent Fasting You Need to be Aware of?

Short term effects may be continuous feelings of hunger, dizziness, irritability, poor thinking and headaches in the beginning several days and these symptoms go away when your body gets used to intermittent fasting practice.

Intermittent fasting is not recommended for people with eating disorders, pregnant, breastfeeding mothers, elderly and vulnerable people.