The How and Why of Fasting to Improve Body Composition and Blood Pressure

The How and Why of Fasting to Improve Body Composition and Blood Pressure

According to Statistics Canada, in 2018, 26.8% of Canadians 18 and older (roughly 7.3 million adults) reported height and weight that classified them as obese. Another 9.9 million (36.3%) adults were classified as overweight – bringing the total population with increased health risks due to excess weight to 63.1% in 2018. Obesity has been linked with many chronic diseases, including hypertension, type 2 diabetes, cardiovascular disease, osteoarthritis and certain types of cancer. One of the main reasons the percentage of overweight Canadians remains elevated is because Canadians are eating too much food and perhaps equally important, they are eating too frequently.

Dr. Anuruddh Misra

Dr. Anuruddh Misra, a double board-certified physician (Sports and Internal Medicine) and InBody Board Advisor, provided first-hand insights regarding his intermittent fasting strategies with his patients. His aim is to redress the common problem of “energy surplus” or “energy toxicity” which manifests as obesity in the patients he attends to. At his practice, he shares what has worked from his first-hand experiences battling the obesity epidemic in America. In fact, Dr. Misra claims that “obesity is a function of over-eating and eating too frequently.” This means that for Americans to regain control of their weight they need to primarily consume fewer calories, however, a less discussed approach to sustainably achieving this is to eat less frequently.  

Recently, intermittent fasting (IF) has become popular due to its health benefits and ability to help individuals lose weight when practiced correctly. The flexibility, ease of adaption, and rapid results available in the short term make fasting an ideal “tool in the toolbox” for one to adapt to a healthy lifestyle.  

This article will lead you through intermittent fasting strategies and learn how this approach can benefit those who struggle with body composition, blood pressure or both.  

What is Intermittent Fasting?

The How and Why of Fasting to Improve Body Composition and Blood Pressure

IF is the choice to refrain from consuming any calorie-containing foods and beverages for a defined period. There are many variations of IF where some individuals simply extend the overnight fast while others might fast for full days during the week. Popular examples of IF variations include: 

  • Time-restricted feeding: the 16/8 diet: where individuals decrease their daily eating window. A common example is too fast for 16 hours of the day and eating freely for the remaining 8 hours. Other intervals practices are 18:6 hours, 20:4 hours, or 22:2hours 
  • One-meal-a-day (OMAD): where individuals consume only one large meal each day 
  • Alternate day fasting: where individuals alternate between days of fully fasting and full eating days  
  • Whole day fasting: where individuals pick 1 or 2 days a week where they don’t consume any calories. A popular strategy is known as the “5:2 diet”. 

IF has become a popular approach to weight management because of its proven effectiveness, and many variations, making it easy for one to find the “perfect fit” to start. One misconception regarding fasting is that “calories don’t count”. Although untrue, fasting generally results in satiety being achieved easily due to the stomach relatively shrinking. When practicing fasting reasonably and responsibly one can worry less about “calorie counting” to achieve their goals. While at first missing a meal may seem difficult, in time one’s physiology adapts to a “new normal” and it becomes easier for the individual to gradually increase their fasting interval. 

How does fasting affect the body? 

Fasting enables the body to burn more fat because when the window of eating decreases, different metabolic pathways in the body are activated, making the body more adept at breaking down stored fat and using that for energy. Dr. Misra’s favorite analogy to explain this technique is explaining a hybrid car: When the body needs energy it can use stored sugar (glucose), aka the gasoline in the car, or stored fat, aka the battery charge in the car. However, if one feeds too frequently, their glucose or “gasoline” levels are not lowered enough for the body to switch to using stored fat for energy. When the body can easily transition between using glucose and body fat as energy, it’s called being “metabolically flexible” and directly translates to a loss in body fat 

To simplify this, when the fasting window is extended, the body is being “trained” to burn more stored fat, which is how individuals lose excess body fat. Dr. Misra says  

“Metabolic flexibility, this is really the key. This is really the goal of fasting because if you can make them [people] metabolically flexible, they can draw down on their internal reservoir [fat] as opposed to being dependent upon external sources for energy. Interestingly, the ultimate superfood is one’s own reservoir of energy – stored body fat.”

Fasting also decreases how frequently our bodies produce an insulin response. Every time we eat a meal, our blood sugar levels increase. This causes our bodies to release a hormone called insulin from the pancreas, which helps bring sugar to the cells to use as energy. Any extra sugar will be sent to the liver to be stored or converted into adipose tissue (body fat).  

If we are constantly eating, then we frequently raise blood sugar and our bodies are constantly producing insulin. Over time, our cells aren’t as sensitive to insulin, meaning our bodies must secrete more insulin to help bring sugar into our cells. If this continues, our cells will stop responding to insulin altogether; this is called insulin resistance. This causes our blood sugar levels to remain high and is the cause of type 2 diabetes 

For most people, the easiest way to reduce body fat and insulin signaling is to go through periods of time when we aren’t eating. This is how our ancestors ate, how our species naturally evolved, and likely how our bodies are optimally designed to handle food. Dr. Misra, who uses fasting to optimize his own health, states 

“I go back to really more of what the human physiology is better adapted to do or is extremely well adapted for, which has feast – famine cycling. Unfortunately, the very thought of fasting itself has a negative stigma to it and it really shouldn’t.”

The loss of excess body fat directly correlates to a decreased risk of metabolic conditions like type 2 diabetes and high blood pressure. Because insulin resistance is the common factor in most cases.  

How does intermittent fasting improve blood pressure?

How does intermittent fasting improve blood pressure?

According to the Heart and Stroke Foundation of Canada9 in 10 Canadians will develop high blood pressure or hypertension during their lives. This is problematic because having hypertension significantly increases your risk of heart disease and stroke, which are the leading causes of death in the United States.  

While there are many strategies to decrease blood pressure, fasting has shown to be extremely effective at decreasing blood pressure. As insulin resistance is improved, one of the first signs is a gradual normalization of blood pressure. This is because when you extend the window of fasting, you are not consuming any sodium, which decreases the body’s sodium levels. Dr. Misra says  

“With sodium goes the water. And with that, it results in a decrease of their blood volume and hence their blood pressure goes down.”

As we mentioned, fasting helps individuals lose body fat, specifically visceral fat. The achievement of negative fat flux is the primary goal with Dr. Misra’s obese patients. This helps to decrease blood pressure because there is less peripheral resistance, which doesn’t require your heart to work as hard to circulate blood throughout your body. Being overweight also causes the kidneys to reabsorb more sodium into the blood while also causing structural changes in the kidneys, which results in an increase in blood pressure 

The decrease in blood pressure associated with weight loss is also due to an increase in insulin sensitivity. This is because insulin increases sodium reabsorption in the kidney while promoting sympathetic nerve activity, which constricts the blood vessels.    

IF also increases certain compounds in the body, such as brain-derived neurotrophic factor (BDNF) and AMP-activated protein kinase (AMPK). Studies have shown that both of these compounds can dilate our blood vessels, which directly decreases blood pressure. 

Lastly, IF can change the composition of your gut microbiome to a favorable balance of gut organisms that help decrease blood pressure. This can also result in some restructuring their palate and they simply are no longer interested in unhealthy, or “junk food”.  

Is fasting for me?

While fasting has many benefits such as: reducing body fat, increasing insulin sensitivity, and decreasing blood pressure. However, it is important to note fasting is not for everyone. If you are considering fasting and are unsure if it’s a good choice for you, speak with your primary care physician before making any decisions. For example, Dr. Misra does not recommend it for individuals with certain physiological disorders, such as a history of disordered eating (anorexia, orthorexia).  

Although Dr. Misra recommends fasting for most of his patients, it’s important to consider your specific situation before starting. The good news is fasting is easily adaptable, generally sustainable for most to incorporate into a lifestyle routine, and usually advantageous to various parts of one’s body and health. When you personalize the fasting approach to the individual, it increases the efficacy of the strategy. Remember, fasting is simply one tool in the toolbox to battle the American obesity epidemic. In the end, it’s important to recognize that fat accumulation and the tendency to overeat lead to many chronic conditions that could be avoided. 

“High blood pressure, stroke, type two diabetes and (more)… there’s a distinct reason insulin resistance is the common denominator to all of these problems – it is because insulin resistance is the root cause.”

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