There are multiple health benefits of fasting, in this post I will try to put some of the top health benefits of fasting. Everyone has a different body and follows a different lifestyle. So everyone experience these benefits on different levels.
Fasting has both mental and physical benefits, fasting also called as purifying or detoxifying to the body. Different duration fasts have different benefits, longer duration fast provides more benefits compared to short duration fasts.
Below are Top 15 health benefits of fasting to the body backed by scientific studies
1 : Weight loss
Fasting makes you lose a lot of weight in the shortest amount of time. In absence of food, body starts burning glycogen stored in liver and muscles (a form of carbohydrates) for energy. After glycogen exhausted, our body starts burning fat for energy, called as “ketosis”. [Study 1,2]
Combining exercise with fasting is the most effective way to lose weight. A person can lose 6-8 lbs. (~ 4 kilograms) in “5-day water fast” Which average to 2 pounds (1 kilogram) per day weight loss. [Study 3,4]
Most of the weight loss is water weight, but around 20 – 25% of weight loss is fat loss. Visceral fat which surrounds organs like liver, kidneys is burned. Muscle mass loss is negligible. So in fasting, overall body composition improves significantly. [Study 5]
2: Boosts metabolism
High metabolic rate associated with healthy and younger body, that’s why teens can digest almost anything and never get fat, even after eating so many times. As we age our metabolism starts to slow down and we get fat.
Studies show that intermittent fasting improves metabolic rate. Fasting gives rest to digestion system, also allows it to recover from damages caused by daily use. Fasting causes toxic substances to go out of the body, hence there is a greater balance of body hormones such as insulin, ghrelin, cortisol etc. Which results in boosting metabolism. [Study 6,7,8]
Fasting lesser than 48 hours shows improved metabolic rate by 14% whereas fast longer than 48 hours slows down metabolic rate. [Study 9]
3: Detoxifying effects
Although body has capabilities of detoxifying itself on regular basis, fasting shown to improve speed of detoxification process.
As we age as our bodies accumulate a lot of toxins. These toxins get stored in body parts such as liver and kidneys.
Our kidneys do work of cleaning blood, and excreting excess toxic substance out of the blood through urine. When the body goes in fasting mode kidney losses lot of water and toxin contained with it. [Study 10]
Liver removes toxic substances from food and also produces “bile” which is essential for food digestion. It also works as storage for vitamins, minerals, proteins, fats, and glycogen. As body goes in fasting liver burns stored glycogen and fat for energy.
Body needs a lot of water to digest carbohydrates and salts, hence it retains a lot of water. Every 1 gm of carbs require 3-4 grams of water to digest it. As we are not eating, the body don’t need excess water. Excess water also contains toxins which are excreted in form of urine. Liver also burns fat for energy which contains toxins. [Study 11]
Inflammation is a major risk factor in the chronic disease like heart disease, arthritis, diabetes, Alzheimer, cancer.
Inflammation is caused by free radicals, which are present in the food we eat. Free radicals produced in various metabolic reactions and responsible for oxidative stress.
High insulin levels are also associated with oxidative stress on cells, which leads to inflammation. Fasting helps to reduce inflammation. One of the key inflammation markers is “hsCRP” (high-sensitivity C-reactive protein), which is used to measure inflammation, after long-term fasting shown to decrease by half. [Study 15]
5: High Growth hormone
Growth hormone is responsible for maintaining muscle mass, metabolic rate, fat burning rate and recovery time. Growth hormone peaks in puberty and as we age Growth hormones slowly goes downhill. Low growth hormone levels lead to more fat and less muscle mass with low bone density. Growth hormone maintains balance in insulin and cortisol levels.
Growth hormone increases availability of fat to be used as energy hence results in fat burning. Artificial growth hormone is given to older men shown several anti-aging effects, however, it is not recommended to everyone due to its side effects. [Study 16, 17]
6: Reverse Ageing
In fasting, body starts a process called “autophagy”. In autophagy, body uses its own cells for energy. Cells used for energy are damaged or broken cells which are toxic for the body. Once the broken or dead cell is used up for energy body replace them with a new working cell. In other words, body renews itself.
Body constantly renews cells over time, in fasting speed of cell recycling increases significantly. Damaged cell replacement with a new working cell is necessary for the body to function normally. Cell damage over years is cause of aging. [Study 20,21]
Food intake as little as 3 -gm of proteins can stops autophagy. When body gets to rest from the big task like food digestion. It can take look at the tasks such as repair and restoration.
7: Increases insulin sensitivity
Insulin is responsible for controlling glucose levels in the blood by converting excess glucose in to fat.
Its well-known fact that increased insulin levels causes weight gain, which means obesity is more related to insulin imbalance. So if we want to lose weight we need to decrease insulin availability in the body.
In modern diet we eat 4-6 times in a day, so insulin levels in the blood are always high. As body get use to these levels, it needs more and more insulin to control glucose in the blood. Body starts to produce more insulin which induces a lot of stress on the kidneys which result in type 2 diabetes.
In fasting no food intake happens, so no insulin secreted in the body. Which results in weight loss. In absence of insulin cells become more receptive to low insulin levels. Lower insulin levels related to low blood sugar and low-fat storage. [Study 24,25]
Studies shown that type 2 diabetes can be reversed by fasting. [Study 26]
8: Normalize blood pressure
High blood pressure related to obesity and weight, when a person does fasting his blood pressure lowers significantly. During fasting body gets rid of excess fat, salt and water in the body.[Study 27]
Initially, in fasting, a person may experience low blood pressure. Slowly body adapts with fasting and blood pressure become normal.
9: Healthy heart
Heart disease is a major killer in an aging population. Caused by chronic inflammation, poor diet, less physical activity, smoking, high blood pressure, high cholesterol etc.
Fasting is beneficial in controlling risk factors which leads to heart problems. Fasting reduces inflammation, lowers triglycerides, bad cholesterol, blood pressure, visceral fat and improve hormonal balance. So fasting is very helpful in keeping the heart healthy. [Study 28, 29, 30]
High Cholesterol with triglycerides associated with heart disease. Dietary cholesterol and blood cholesterol are both different things. Body produces its own cholesterol from triglycerides.
In fasting mode there is a shortage of glucose, excess glucose is responsible for the formation of triglycerides in the liver. Low triglycerides results in low cholesterol production in liver
10: Helps to maintain muscle mass
Fasting help to maintain muscle mass compared to calorie restricted diet. When we go on calorie restricted diets to lose weight we not only lose fat but also lean muscle mass which is harmful for body functions. That is why fasting is good for athletes.
Muscle burns more calories when resting, so loosing muscle mean burning fewer calories and results in hard to lose weight after initial phase. [Study 31]
11: Improve body composition and tighter skin
Low fat levels are required for tighter and firm skin, when we lose weight skin remains loose for longer duration’s. In fasting when autophagy happens body regenerate new skin which is tighter and shining. [Study 32,33 ]
12: Improved immune system
Short-term fasting for 2-3 days can completely reset the immune system even in elderly people.
It provides the most benefits to people with low immunity due to old age or chemotherapy.
13: lower cortisol levels
Cortisol also called as the stress hormone. Cortisol secreted in the morning to awaken body. Also when body is in any kind physical or mental stress, it produces cortisol. Increased cortisol result in “flight or fight response” and keeps body in alert state. It’s an evolutionary survival mechanism of body. Increased cortisol associated with disturbed sleep and eating habits. Increased cortisol associated with weight gain
14: Lowers risk of chronic disease
Insulin resistance and inflammation are related to various chronic diseases like Cancer [Study 39,40,41,42, 43 ], type 2 diabetes, heart disease, stroke, fatty leaver, Alzheimer [Study 44], Parkinson’s disease [Study 45] , Arthritis, sleep apnea which directly affect life quality and longevity.
Fasting is the most efficient and natural way to Improve insulin sensitivity. Keeps the glucose level to normal in the blood.
Give rest to important organs which focus on repair and recovery.
Our brain uses 20% of energy consumed by our body, which means brain is the biggest energy consumer in body. Brain needs constant energy supply as it governs other organs in the body. Most of the time brain is fine with Glycogen in the body which is a form of glucose. Glycogen stores lasts around ~24-48 hours. When glycogen used up, body starts burning fat for energy. Body goes into ketosis and it produces ketones from fat, and these ketones used by the brain as fuel.
Ketones provide constant energy to the brain, whereas glycogen energy levels fluctuate hence we have the sense of mental clarity and energy.
Fasting provides multiple benefits to human body for both physical and mental health.
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