First of all, fasting is not starvation. Starvation is the involuntary abstinence from eating forced upon by outside forces; this happens in times of war and famine when food is scarce. Fasting, on the other hand, is voluntary, deliberate, and controlled. Food is readily available but we choose not to eat it due to spiritual, health, or other reasons.
Fasting is as old as mankind, far older than any other forms of diets. Ancient civilizations, like the Greeks, recognized that there was something intrinsically beneficial to periodic fasting. They were often called times of healing, cleansing, purification, or detoxification. Virtually every culture and religion on earth practice some rituals of fasting.
Before the advent of agriculture, humans never ate three meals a day plus snacking in between. We ate only when we found food which could be hours or days apart. Hence, from an evolution standpoint, eating three meals a day is not a requirement for survival. Otherwise, we would not have survived as a species.
Fast forward to the 21st century, we have all forgotten about this ancient practice. After all, fasting is really bad for business! Food manufacturers encourage us to eat multiple meals and snacks a day. Nutritional authorities warn that skipping a single meal will have dire health consequences. Overtime, these messages have been so well-drilled into our heads.
Fasting has no standard duration. It may be done for a few hours to many days to months on end. Intermittent fasting is an eating pattern where we cycle between fasting and regular eating. Shorter fasts of 16-20 hours are generally done more frequently, even daily. Longer fasts, typically 24-36 hours, are done 2-3 times per week. As it happens, we all fast daily for a period of 12 hours or so between dinner and breakfast.
Fasting has been done by millions and millions of people for thousands of years. Is it unhealthy? No. In fact, numerous studies have shown that it has enormous health benefits.
What Happens When We Eat Constantly?
Before going into the benefits of how to fast intermittent fasting, it is best to understand why eating 5-6 meals a day or every few hours (the exact opposite of fasting) may actually do more harm than good.
When we eat, we ingest food energy. The key hormone involved is insulin (produced by the pancreas), which rises during meals. Both carbohydrates and protein stimulate insulin. Fat triggers a smaller insulin effect, but fat is rarely eaten alone.
Insulin has two major functions –
- First, it allows the body to immediately start using food energy. Carbohydrates are rapidly converted into glucose, raising blood sugar levels. Insulin directs glucose into the body cells to be used as energy. Proteins are broken down into amino acids and excess amino acids may be turned into glucose. Protein does not necessarily raise blood glucose but it can stimulate insulin. Fats have minimal effect on insulin.
- Second, insulin stores away excess energy for future use. Insulin converts excess glucose into glycogen and store it in the liver. However, there is a limit to how much glycogen can be stored away. Once the limit is reached, the liver starts turning glucose into fat. The fat is then put away in the liver (in excess, it becomes fatty liver) or fat deposits in the body (often stored as visceral or belly fat).
Therefore, when we eat and snack throughout the day, we are constantly in a fed state and insulin levels remain high. In other words, we may be spending the majority of the day storing away food energy.
What Happens When We Fast?
The process of using and storing food energy that occurs when we eat goes in reverse when we fast. Insulin levels drop, prompting the body to start burning stored energy. Glycogen, the glucose that is stored in the liver, is first accessed and used. After that, the body starts to break down stored body fat for energy.
Thus, the body basically exists in two states – the fed state with high insulin and the fasting state with low insulin. We are either storing food energy or we are burning food energy. If eating and fasting are balanced, then there is no weight gain. If we spend the majority of the day eating and storing energy, there is a good chance that overtime we may end up gaining weight.
Intermittent Fasting Versus Continuous Calorie-Restriction
The portion-control strategy of constant caloric reduction is the most common dietary recommendation for weight loss and type 2 diabetes. For example, the American Diabetes Association recommends a 500-750 kcal/day energy deficit coupled with regular physical activity. Dietitians follow this approach and recommend eating 4-6 small meals throughout the day.
Does the portion-control strategy work in the long-run? Rarely. A cohort study with a 9-year follow-up from the United Kingdom on 176,495 obese individuals indicated that only 3,528 of them succeeded in attaining normal body weight by the end of the study. That is a failure rate of 98%!
Intermittent fasting is not constant caloric restriction. Restricting calories causes a compensatory increase in hunger and worse, a decrease in the body’s metabolic rate, a double curse! Because when we are burning fewer calories per day, it becomes increasingly harder to lose weight and much easier to gain weight back after we have lost it. This type of diet puts the body into a “starvation mode” as metabolism revs down to conserve energy.
Intermittent fasting does not have any of these drawbacks.
Health Benefits Of Intermittent Fasting
Increases metabolism leading to weight and body fat loss
Unlike a daily caloric reduction diet, intermittent fasting raises metabolism. This makes sense from a survival standpoint. If we do not eat, the body uses stored energy as fuel so that we can stay alive to find another meal. Hormones allow the body to switch energy sources from food to body fat.
Studies demonstrate this phenomenon clearly. For example, four days of continuous fasting increased Basal Metabolic Rate by 12%. Levels of the neurotransmitter norepinephrine, which prepares the body for action, increased by 117%. Fatty acids in the bloodstream increased over 370% as the body switched from burning food to burning stored fats.
No loss in muscle mass
Unlike a constant calorie-restriction diet, intermittent fasting does not burn muscles as many have feared. In 2010, researchers looked at a group of subjects who underwent 70 days of alternate daily fasting (ate one day and fasted the next). Their muscle mass started off at 52.0 kg and ended at 51.9 kg. In other words, there was no loss of muscles but they did lose 11.4% of fat and saw major improvements in LDL cholesterol and triglyceride levels.
During fasting, the body naturally produces more human growth hormone to preserve lean muscles and bones. Muscle mass is generally preserved until body fat drops below 4%. Therefore, most people are not at risk of muscle-wasting when doing intermittent fasting.
Reverses insulin resistance, type 2 diabetes, and fatty liver
Type 2 diabetes is a condition whereby there is simply too much sugar in the body, to the point that the cells can no longer respond to insulin and take in any more glucose from the blood (insulin resistance), resulting in high blood sugar. Also, the liver becomes loaded with fat as it tries to clear out the excess glucose by converting it to and storing it as fat.
Therefore, to reverse this condition, two things have to happen –
- First, stop putting more sugar into the body.
- Second, burn the remaining sugar off.
The best diet to achieve this is a low-carbohydrate, moderate-protein, and high-healthy fat diet, also called ketogentic diet. (Remember that carbohydrate raises blood sugar the most, protein to some degree, and fat the least.) That is why a low-carb diet will help reduce the burden of incoming glucose. For some people, this is already enough to reverse insulin resistance and type 2 diabetes. However, in more severe cases, diet alone is not sufficient.
What about exercise? Exercise will help burn off glucose in the skeletal muscles but not all the tissues and organs, including the fatty liver. Clearly, exercise is important, but to eliminate the excess glucose in the organs, there is the need to temporarily “starve” the cells.
Intermittent fasting can accomplish this. That is why historically, people called fasting a cleanse or a detox. It can be a very powerful tool to get rid of all the excesses. It is the fastest way to lower blood glucose and insulin levels, and eventually reversing insulin resistance, type 2 diabetes, and fatty liver.
By the way, taking insulin for type 2 diabetes does not address the root cause of the problem, which is excess sugar in the body. It is true that insulin will drive the glucose away from the blood, resulting in lower blood glucose, but where does the sugar go? The liver is just going to turn it all into fat, fat in the liver and fat in the abdomen. Patients who go on insulin often end up gaining more weight, which worsens their diabetes.
Enhances heart health
Overtime, high blood glucose from type 2 diabetes can damage the blood vessels and nerves that control the heart. The longer one has diabetes, the higher the chances that heart disease will develop. By lowering blood sugar through intermittent fasting, the risk of cardiovascular disease and stroke is also reduced.