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Intermittent Fasting

Weight Loss in Intermittent Fasting – Why It Works

Sep 19, 2019

Intermittent fasting is not some quick-fix diet for weight loss. Instead, Intermittent Fasting (IF) is a timed approach to losing excess body fat, and keeping it off in the long run. Unlike other traditional diets that restrict calories or food groups, intermittent fasting becomes a lifestyle change that involves cycling between periods of eating and short-term fasting.

When you are intermittent fasting, you are free to eat most foods (with exceptions like added sugar and highly processed foods) and enjoy a varied diet, but over a shorter window of time. Simply put, IF gives you the freedom to eat almost whatever you like and still lose weight, as well as keep it off for good!

How, you ask? One way is that eating during a shorter period of time helps control intake of calories to keep unwanted weight off. But that’s not the real reason. The core reason is that IF helps reduce the amount of insulin secreted in the body. Insulin is our fat storage hormone and the shorter the time it is active for in our blood, the more the fat burnt and the greater the weight  loss.

There are many ways to practice intermittent fasting but the most popular ones are:

  • The 16:8 Method: The most popular way to practice IF, it encourages 16 hours of fasting with 8 hours eating window. Skip breakfast, and eat two big meals between say 12 noon to 8pm.
  • The 5:2 or Alternate Day Fasting: This method promotes alternate day fasting on two days of the week, wherein a person consumes just 500-600 calories on those two days. Eat normally the other 5 days of the week.
  • Eat-Stop-Eat: This involves fasting for 24 hours on two non-consecutive days of the week. For example: fast from breakfast on Tuesday until breakfast on Wednesday.

How Does Intermittent Fasting Affect Hormones

Intermittent fasting targets stored body fat. When you don’t eat over a period of time, the body makes integral changes to use up stored fats to release energy. And to make this happen, there are crucial changes in metabolism and hormone activity — all of which benefit you in the long run. This is why IF works so well for weight loss in chronic diseases that are caused by hormonal imbalances, like Diabetes Type 2, cholesterol issues and PCOS.

  • Insulin: When we eat, insulin levels rise. Similarly, when the body is fasting, insulin levels drop down to facilitate fat burning. 
  • HGH: Fasting increases levels of HGH or Human Growth Hormone 5 times, which promotes fat loss while aiding muscle gain.
  • Noradrenaline: During fasting, the nervous system sends norepinephrine or noradrenaline to fat cells to break them down. This breakdown of stored body fat into free fatty acids that fuels the body results in weight loss.

IF promotes hormonal changes in the body that actually boosts fat burning to encourage weight loss. This is why IF is far more successful that other conventional calorie-restrictive diets when it comes to losing excess body fat without losing muscle mass.

The 6 Ways Intermittent Fasting Helps You Lose Weight

Calorie Restriction

Intermittent fasting helps control your calorie intake by its very design. By limiting the eating window, you end up eating fewer calories, without the hassle of counting or measuring calories. Since all the three IF protocols involve periods of fasting, you end up skipping meals, which means lesser overall calorie intake. But remember: even diet plans that ask you to eat six small meals a day achieve this calorie restriction. The crucial difference is that IF positively influences the way your hormones behave over a longer term, which the many-small-meals-a-day weight loss programmes don’t.

A review study conducted at University of Illinois at Chicago found that IF leads to significant weight loss and is a great alternative to controlled calorie restrictive diets. Subjects lost up to 0.75kg per week with alternate-day fasting method, while those who tried 16:8 method lost about 0.25kg per week.

Lowered Insulin Levels

Intermittent fasting has a two-pronged effect on insulin function.

One – it improves insulin sensitivity through increased adiponectin levels which can help weight loss as well as insulin function in diabetics.

Two – fasting helps reduce fasting insulin levels that signals your body that it’s time to burn stored fat (instead of glucose) to release energy.

A study conducted at Pennington Biomedical Research Center, LA found that alternate day fasting increased fat oxidation (or fat burning) while also reducing insulin levels by 4%. Another study conducted at California State University found intermittent fasting (or time-restricted feeding) to be beneficial for preventing metabolic syndrome as it promotes decreased body weight , lower concentrations of triglycerides, glucose, and low-density lipoprotein cholesterol, while increasing concentrations of high-density lipoprotein cholesterol. 

Improved Cholesterol

As mentioned above, intermittent fasting can reduce risk to metabolic syndrome because this diet doesn’t just help you lose weight; it also positively impacts cholesterol levels. IF can help decrease levels of LDL and VLDL (bad cholesterol). These high LDL and VLDL levels contributes towards belly fat, which is why IF can be a sustainable way to lose that belly bulge that just won’t budge!

A study conducted at Pennington Biomedical Research Center, LA noted that subjects noticed higher loss of visceral body fat – up to 4-7% of their waist circumference. Other studies have found that 24-hour fasting intervention acutely increased high-density lipoprotein cholesterol and decreased triglycerides and weight, compared to a day of usual eating.

Boosts Resting Metabolism

Intermittent fasting helps boost resting metabolism, thanks to the action of norepinephrine or noradrenaline. Put simply, when you are fasting, your body burns more calories even during rest. Research conducted at University of Vienna, Austria found that during fasting, resting energy expenditure increases, accompanied by an increase in plasma norepinephrine.

Another study from Queen’s Medical Centre, UK found that 48 hour fasting led to considerable alterations in basal metabolism including a significant (mean 3.6%) increase in resting metabolic rate. 

Reduces Inflammation

Any form of inflammation poses stress on the body. Stress is interpreted in the body as a signal that you may be in a famine situation (ancient evolutionary response), so the body desperately holds on to fat, just in case you need the fat to survive till you can find food again. Intermittent fasting helps in decreasing oxidative stress and inflammation throughout the body. This in turn leads to the body feeling comfortable with burning stored fat and losing weight.

Lowered inflammation is the key to long-term weight loss, along with reducing risk to metabolic syndrome, cancer and Alzheimer’s. Review studies have found that IF promotes human metabolic health by significant improvements in inflammatory markers that boost weight loss while boosting longevity.

Promotes Ketosis

With the popularity of the Keto diet, most of us know that ketosis helps achieve fast weight loss. (Note: Ketosis is a metabolic sate when the body does not have enough glucose for energy. It burns stored fats instead which leads to creation of acids called ketones in the body). But did you know that intermittent fasting makes it easier for you to reach full ketosis? Intermittent fasting, when coupled with a low carb diet, is an easier shortcut to reach fat-burning state faster.

Study conducted at University of Texas Medical Branch found that mobilization of adipose tissue triglycerides (or simply put – fat) increases markedly between 18 and 24 h of fasting in young adult men. Ketosis helps you to not just drop weight fast but also boosts heart health, reduces inflammation and improves blood chemistry.

Tips to Make Intermittent Fasting More Successful

The biggest reason intermittent fasting really works well is because it is simple. There’s no counting calories, there’s no hard-and-fast rules as to what you can eat (beyond not bingeing on processed foods and added sugar) and it even allows you to have a normal social life, wherein you can enjoy lunch or dinner out with friends and family.

Eating 2 meals instead of 3 meals makes it a lot simpler for you to stick to a healthy lifestyle. And as we all know, the best diet for you is one you can stick to for life! Intermittent Fasting is one of those diets that let you enjoy benefits of improved long-term health and easy weight management, without a whole lot of fuss.

Start your day with the right beverage

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If the idea of skipping breakfast sounds too daunting, start the day with a beverage. Sip on a cup of bulletproof coffee (black coffee with added butter or coconut oil), unsweetened green tea or a mug of bone broth during fasting window to keep from becoming hangry (hungry and angry).

Follow a low-carb diet

While intermittent fasting doesn’t come with any hard and fast rules, it’s a good idea to follow a low-grain carb diet during feeding window. A diet low in grain carbs but high in healthy fats and proteins will keep you feeling satiated for longer and also make it easier for your body to transition into ketosis when in fasting state.

Stay away from processed foods

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What you eat is still important! Even though you may be starving at the end of your fasting window, it is important to steer clear of processed and junk foods. These will do no favours to your waistline and will only stall your weight loss journey. Eat whole foods that offer you a variety of nutrients.

Consistency is the key

Like all diet protocols, it takes time for your body to get used to intermittent fasting. Don’t give up! Consistency is the key to losing weight with intermittent fasting. Be patient and stick to a fixed meal schedule to make things easier in the beginning. If you are trying the 16:8 method, keep your eating times same to build a routine your body can get used to.

Other factors matter

For intermittent fasting to lead to successful long-term weight loss, other factors also come into play. Regular exercise with strength training helps build your muscle mass while IF results in fat-loss. Also, make sure you follow a healthy bedtime routine and get 8 hours of sleep to keep away those late-night munchies for better weight management.

Sharda Agarwal

Sharda Agarwal

Co-founder, Sepalika. Nutritional Therapy Practitioner, Nutritional Therapy Association, USA
Sharda Agarwal is a qualified Functional Nutrition Therapy Practitioner & a Certified Blood Chemistry Analyst. She first used dietary supplements to overcome a debilitating migraine she suffered for years. Since then she has studied the subjects of nutrition and nutrients extensively. She uses this to manage the health of her family at home and with Sepalika.


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Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men –

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Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings –

Time-restricted feeding and risk of metabolic disease: a review of human and animal studies –

Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine –

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Effect of intermittent fasting and refeeding on insulin action in healthy men –

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Progressive alterations in lipid and glucose metabolism during short-term fasting in young adult men –