Updated: 2021, Apr 11

The Ultimate Guide to Intermittent Fasting

Learn more about the intermittent fasting for weight loss. But how do you do it and is it safe? Read the health benefits, foods to include in your diet & more.


The Ultimate Guide to Intermittent Fasting
Intermittent fasting is not a diet, it's a pattern of eating. Image/Shutterstock

  • Intermittent fasting: The fasting phase can be for 8, 10 or 12 hours
  • The idea is to not starve yourself
  • Intermittent fasting can be helpful for weight loss

When it comes to healthy lifestyle choices, many diets have come and gone, but one that has gained more and more popularity over the past few years is intermittent fasting or IF.

Whether you have dabbled in intermittent fasting before, or are a complete newbie looking for a place to begin, this article contains a plethora of information to help you lose weight through intermittent fasting.

What is Intermittent Fasting?

Intermittent fasting is a broad term used for a number of meal scheduling plans. It is also labeled intermittent energy restriction in some places. Simply put, it is a way of consuming food by breaking your day into periodic short term fasts, or a cycle of fasting and non-fasting periods.[2]

Restricting your consumption of food to a small time window during the day is a proven and effective way to shed weight. It conveniently allows calorie restriction without having to go through the hassle of calorie counting or weighing out meal portions.

How Does It Optimize Weight Loss?

Intermittent fasting is responsible for inducing several changes to your system that make your body a fat-burning machine.

Short term fasting lowers your insulin levels, promotes the production of the human growth hormones (HGH), and boosts your metabolism by enhancing the epinephrine signaling within your system.[4]

All of these contribute to making your body burn fat more effectively, optimizing weight loss. However, one of the main proponents of this method is the fact that when you are fasting intermittently for weight loss, you automatically eat fewer calories.

How Do I Get Started on Intermittent Fasting?

There are many different methods that people swear by for intermittent fasting. All of these methods follow the same basic protocol; a longer fasting period where you skip meals, and a shorter window or eating period.

Some popular methods of IF are:


*All individuals are unique. Your results can and will vary.

  • Alternate-day fasting, where you fast for 24 hours, then eat normally the next day, and repeat.
  • Periodic fasting, where you set up fasting periods over the week
  • Daily restricted time feeding, where you fast for some hours every day, then break your fast

Periodic fasting and daily restricted time methods follow similar protocols and divisions. Some popular ones are:

  • 16/8: Out of 24 hours in a day, you are allowed to eat during an 8-hour feeding window, e.g. 2 pm-10pm
  • OMAD: OMAD stands for One-Meal-A-Day. Here you are fasting for 24 hours, having one full meal, and then fasting for another 24. e.g. not eating from lunch one day to lunch the next day.
  • The 5:2: Here, one consumes a normal intake of calories for 5 days, but restricts them to under 500 for the next two days.

How Does Intermittent Fasting Works at the Hormonal Level?

Our bodies store extra energy from the calories we consume in the form of fat all over our bodies. When we are in fasting mode, our body chemistry tweaks itself at the hormonal level to make the fat accessible as energy reservoirs. These changes happen in our nervous and endocrine systems, which result in several crucial hormones, or the big guns, coming out to play.

  • When we eat, our insulin levels increase. Fasting drastically reduces our insulin levels which facilitate the fat-burning capabilities of our bodies.
  • Levels of HGH, or the human growth hormone, increase dramatically during fasts. These high levels of HGH aid muscle gain. Muscles burn more calories than fat so that automatically increases weight loss.
  • When we fast, the brain jumps into action and sends the hormone norepinephrine or noradrenaline to the fat deposits in your body. This hormone makes the body fat break down into smaller chunks of fatty acids that can be easily burnt by the body for energy.

Can I Eat Absolutely Anything During My Non-Fasting Window?

Technically yes, but realistically no. Even though you are not required to count calories generally while fasting intermittently, one of the main proponents of weight loss is largely mediated reducing calorie intake overall. The quality of the food you eat also matters.

If you continue to make healthy choices and eat “normally” when you are in your non-fasting window, not trying to make up for missed calories during fasting periods, you should be okay. However, if you overcompensate by eating excessively or consuming very high caloric value foods during the non-fasting period, you will not lose weight.

How Can I Succeed with an Intermittent Fasting Protocol?

If you are interested in the weight loss benefits of intermittent fasting, you must keep a check on a few contributing factors that can make or break your success.

  • Calories: Even though you are not required to count calories generally while fasting intermittently, calories still count. Eat normally during non-fasting periods and don’t overindulge or over-compensate. This is an especially important factor to consider if your weight loss stalls.
  • Food choices: Maintain healthy food choices. The quality of the calories you consume is very important. The foods you consume affect you. Choose healthy alternatives and eat whole or single-ingredient foods.
  • Consistency: Like any other weight loss regime, consistency is key. Our bodies can take some time to adapt to any change in lifestyle habits. The same applies to any intermittent fasting protocol. Stay consistent with your eating schedule. You need to sustain your intermittent fasting over an extended duration to get the best results, or any results at all actually.
  • Exercise: Many popular intermittent fasting protocols highly encourage exercise and strength training. Including cardio to your day helps boost weight loss while strength training is important if you don’t want to lose muscle mass.[5]

While there can never be a “one-size-fits-all” weight loss plan, intermittent fasting has shown impressive results time and again, and is among the top of the lists of useful weight loss methods.

It also makes it easier to eat healthily and takes a lot of the planning fuss away which is a cornerstone for most weight loss programs. But the benefits of intermittent fasting far exceed just weight loss.

There are numerous other health benefits associated with intermittent fastings, like improved metabolic health, prevention of chronic diseases, and extended lifespans.[3]

The “best” diet for you is one that you feel like you can adopt as a lifestyle change. If you feel that intermittent fasting seems easier for you to stick to, then why not consult your doctor and start today.

References & Research

[1] Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6521152/ Martin M. Grajower and Benjamin D. Horne
[2] Intermittent Fasting: Is the Wait Worth the Weight? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959807/ Mary-Catherine Stockman, RD, LDN, Dylan Thomas, MD, Jacquelyn Burke, MS, RD, and Caroline M. Apovian, MD
[3] Impact of intermittent fasting on health and disease processes https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5411330/ Mark P. Mattson, Valter D. Longo, and Michelle Harvie
[4] Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC329619/ K Y Ho, J D Veldhuis, M L Johnson, R Furlanetto, W S Evans, K G Alberti, and M O Thorner
[5] Intermittent Fasting Promotes Fat Loss With Lean Mass Retention, Increased Hypothalamic Norepinephrine Content, and Increased Neuropeptide Y Gene Expression in Diet-Induced Obese Male Mice https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4733124/ Juliet D. Gotthardt, Jessica L. Verpeut, Bryn L. Yeomans, Jennifer A. Yang, Ali Yasrebi, Troy A. Roepke,corresponding author and Nicholas T. Bello


Sam Kramer is a Registered Dietitian, Licensed Dietitian Nutritionist, Six Sigma Green Belt Certified, and Certified Sports Nutritionis

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