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Intermittent Fasting: Myths vs Realities

When there is so much buzz around intermittent fasting, it’s hard to tell what’s fact or fiction. Intermittent fasting is an eating pattern where you cycle between periods of eating and fasting. Want to know if it’ll work for you? SlimFast Plan Consultant and Registered Dietitian, Maryann Walsh breaks down the all the rumors and known medical realities around IF!

With the growing popularity of intermittent fasting, there is no shortage of myths and rumors that circulate about this dietary approach. Whether you see or heard about intermittent fasting on websites, through social media, or even amongst conversations with people you encounter each day, it’s important to do a little digging or fact-checking to make sure that what you are hearing is actually true! Let’s discuss some common myths about intermittent fasting as well as some realities when it comes to this dietary approach.

Myth vs. Reality on Intermittent Fasting 1

Intermittent Fasting Puts the Body into Starvation Mode

There is a myth that intermittent fasting can put your body into “starvation mode” causing a significant decrease in the amount of calories you burn. Fortunately, there is research that states otherwise, so this shouldn’t be a major concern for those considering intermittent fasting. In a recent study, short-term fasts were shown to cause an average increase of 3.6% in resting metabolic rate1. The benefit seemed to decline after 48 hours, supporting the idea that short-term fasts are more likely to have a beneficial effect than long-term fasts.

Skipping Breakfast Is Bad For You

Breakfast is often celebrated as the most important meal of the day, and for many, breakfast can be a helpful way to feel fueled and ready to take on the day. However, not everybody is a breakfast eater, and many who practice intermittent fasting can skip breakfast and still feel great while achieving their weight management or nutrition goals.

There is quite a bit of research supporting the consumption of breakfast and how it relates to successful weight management however there is also research that supports the idea that there is no major difference in weight for those who eat breakfast versus those who don’t. At the end of the day, it comes down to numerous factors in one's life that contributes to weight management as well as how one feels overall each day. Inevitably, just like everything else when it comes to diet and nutrition, it comes down to the individual and what feels best for them2.

Intermittent Fasting Is Bad For Focus and Cognitive Function

When the body has a steady supply of carbohydrates, this means it has a steady supply of glucose which can serve as a main source of energy for the brain. However, in the absence of calorie intake during a fast, the brain needs to seek alternative energy sources. The brain can use ketones for fuel which are derived from stored fats and it can also derive energy from a process called gluconeogenesis, which is when the body can use substances like amino acids (the building blocks of protein) that are stored in the liver to produce energy for the brain3,4.

While these processes should hopefully ensure that cognitive function thrives during a fast, everyone is different, so if you feel light-headed and fatigued during a fast, then it may not be an appropriate approach for you.

Myth vs. Reality on Intermittent Fasting 3

You Can’t Drink Water during A Fast

While there is such a thing as “dry fasting” where water is prohibited, this is a more aggressive approach that still lacks a considerable body of research supporting its benefits for weight loss. When following other methods of intermittent fasting, water is allowed and is highly encouraged to prevent dehydration. Water does not cause spikes in blood sugar therefore will not break a fast, also, black coffee, tea, and sugar-free beverages often are allowed on most fasts6. Different brands can vary however so make sure to check the label to ensure the beverage is sugar-free and calorie-free.

You Can Eat As Many Calories As You Want During A Fast

Many claims circulate about intermittent fasting, one of them is that you can eat as many calories as you want during your feeding window. The current body of research suggests that those who achieve weight loss success with intermittent fasting are consuming calories within an appropriate deficit to allow for weight loss, therefore this claim doesn’t currently hold much validity5. The nature of how intermittent fasting works may present a major advantage for those who have trouble controlling their calorie intake in the evenings, giving them a start and stop window for food consumption, which in turn helps one to achieve and maintain a caloric deficit.

Myth vs. Reality on Intermittent Fasting 2

Intermittent Fasting May Be Beneficial For Cellular Repair

Research supports the link between intermittent fasting and the metabolic process known as autophagy, which is the body’s process of cleaning up, recycling, and repairing damaged cells. This mechanism continues to grow as a potential targeted solution for numerous conditions as well as overall health and well-being7.

IF is Linked to Supporting Reductions in Inflammation

There is a growing body of research that supports intermittent fasting for supporting reductions in inflammation. Chronic inflammation is tied to numerous conditions throughout the human body and is often a focus for many who are trying to better their overall health8.

Fasting Has Been Linked To Long Term Brain Health

Intermittent fasting has been shown by research to support an increase in the production of a protein called brain-derived neurotrophic factor (BDNF), which is protective from neurological changes that are associated with numerous disorders involving cognitive impairment9. While research is still limited and mostly in rodents, it is still encouraging to see that intermittent fasting may have such impressive benefits.

Myth vs. Reality on Intermittent Fasting 4

It Can Be a Great Approach for Many People While a Not-So-Great Approach For Others

With all of the buzz around intermittent fasting for not just weight loss but also numerous physiological and health benefits, it’s no surprise that many want to try to integrate an intermittent fasting approach into their diet. However, despite the numerous possible benefits it simply isn’t for everyone.

Intermittent fasting may not be sustainable or suitable for those who are prone to weakness or lightheadedness when going too long between meals (whether they have a diagnosed medical condition or not). Intermittent fasting may also not be a reasonable approach for those people living with diabetes or those that are on certain medications, so it’s important to always discuss with your doctor or healthcare provider if you plan to try intermittent fasting.

Fasting Can Be Integrated Into Any Dietary Approach

While intermittent fasting is often discussed in conjunction with those following a ketogenic diet, it can be combined with any dietary approach, whether someone is just counting calories, if they follow a vegan or vegetarian lifestyle, a low carb lifestyle, etc. You can incorporate intermittent fasting with any of the SlimFast Plans: Keto, Low-Carb, Favorite Foods, or Original, you can check out this blog post to learn more about how the SlimFast Plans work with intermittent fasting.

Hopefully the information provided was able to clear up some confusion that you may have had surrounding myths and realities about intermittent fasting. As with any dietary approach, it’s always important to be educated and informed to decide if it is a good fit for you as well as to set yourself up for success if you choose to move forward in trying it. As mentioned prior, if you are planning on incorporating intermittent fasting into your lifestyle then check with your doctor, especially if you have any medical conditions or are on any medications.

Need support and motivation on your weight loss journey? Join one of the SlimFast Together Private Facebook groups! These groups provide a wealth of tips, advice, and a community of individuals just like you who are either on a weight loss journey or are maintaining their weight and adopting new healthy habits! Click here for more info and to join!






A consultant of the SlimFast Plan, Maryann is a Registered Dietitian with Bachelor of Science degrees in Biological Sciences and Dietetics and a Master of Food and Nutrition. She has extensive experience working with clients of all ages and from all walks of life, helping them to achieve their wellness and weight-loss goals. Learn more about Maryann.