Science-Backed Benefits of Intermittent Fasting

Bismillahir Rahmanir Raheem

What is intermittent fasting?

Diet plans are nowadays available all over the media. They usually focus on what to eat, while intermittent fasting is all about timing—that is, when to eat.

Intermittent fasting benefits

Intermittent fasting burns more fat and this is proven by multiple researches worldwide..”

New England Journal of Medicine: Mattson’s studies showed the data which reveals a wide range of health benefits linked with intermittent fasting.

These benefits are :

A longer life span
A leaner body
A sharper mind

According to Mattson “during intermittent fasting multiple changes occur that protect our body organs against chronic illnesses like heart diseases, type 2 diabetes mellitus, neurodegenerative disorders(age-related), inflammatory bowel disease and even many cancers.

So far researches have revealed some intermittent fasting benefits which are:

Heart: Blood pressure and resting heart rates are improved by Intermittent fasting improved.
Memory: Researches have proved that in animals intermittent fasting boosts working memory and in humans it improves verbal memory
Obesity and Type 2 diabetes: Snimal studies have shown that obesity is prevented by intermittent. Six small scale studies where adult obese individuals have lost weight by adopting intermittent fasting. Most of researches have showon that intermittent fasting helped people to lose body weight and this also helped them in lowering their fasting levels fasting glucose, insulin and leptin levels and also reduced insulin resistance by decreasing leptin levels and increasing adiponectin levels. Also studies found out that a number of patients who religiously followed intermittent fasting under the supervision of doctors, miraculously reversedtheir insulin therapy requirement.
Tissue well being: Very interesting, researches in animals have shown reduced tissue damage in surgery and improved surgical results with intermittent
Physical activity: Individuals who fasted for 16 hours have shown by loosing while maintaining muscle mass have helped in better physical performance. In studies mice were fed on alternate days and they have shown better endurance while running.

Fasting and Metabolism

Fasting interestingly, benefits your metabolism and metabolic health. It increases many fat-burning hormones.

Hormones are chemical messengers. They travel to coordinate complicated functions like metabolism and growth. In addition to these functions these hormones play a vital role in weight regulation by having a strong influence on the appetite, the number of calories consumed and how much fat is burned or stored. Emerging role of the brain in the homeostatic regulation of energy and glucose metabolism. PMCID: PMC4892882. DOI: 10.1038/emm.2016.4

Intermittent fasting also leads to improvements in the balance of fat-burning hormones. So it is figured out that it can be used as a useful tool for weight management.

Insulin

In fat metabolism, insulin is one of the vital hormones. It makes the body store fat and also stops from fat break fat down. Chronic high insulin levels can make it harder to lose weight. High levels of insulin are linked to multiple health disorders, such as obesity, heart disease, type 2 diabetes and cancer. Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings. PMID: 24993615, DOI: 10.1016/j.trsl.2014.05.013

For lowering insulin level intermittent fasting has been shown to be equally effective as calorie-restricted diets. This eating habit also helps in the reduction of fasting insulin levels by 20–31%.

Norepinephrine

Norepinephrine is a stress hormone, it improves alertness and attention and isrelated to the “fight or flight” response. It also havemultiple effects on human body and one of these is asking to release fatty acids from fat cells. Increase in this hormone leads to availability of large amounts of fat being available for the body to be used.

Fasting results in rise in the amount of norepinephrine in the bloodstream.

Human growth hormone

A rise in blood levels of growth hormone happens by fasting and is a vital hormone for the promotion of fat loss.

In men few studies have shown that, growth hormone levels may increase by to fivefold while fasting. Increases in blood growth hormone levels not only promote burning of fat, but also do muscle mass preservation with other added benefits. On the other hand in women same benefits are not always experienced from fasting as in men.Currently it is not clear scientifically if women show the same increase in the growth hormone.

14% metabolism boost is seen in Short-term fasts

People strongly believe that skipping meals leads to adaptation of the body by lowering its metabolic rate in order to save energy.It’s a well established fact that very long periods of fating causes a drop in the metabolism. However, few studies have shown that short period fasting actually causes increase in the metabolism rather then slowing it. One study with 11 healthy men found that a 3-day fast leads to an increase in their metabolism by an impressive 14%.

More high quality, larger study groupsresearches are needed to carefully evaluate the impact of intermittent fasting on metabolism.

As compared to continuous calorie restrictionIntermittent fasting decreases metabolism lesser

When an individual loses weight, the metabolic rate goes down. One of the reasons of this is weight loss leads to muscle loss, and muscle burns round-the-clock calories. However, metabolic rate decrease with weight loss is not completely explained by muscle mass loss alone.

On the other hand a long period of severe calorie restriction causesa drop in metabolic rate as body enters into starvation mode, which is known as “adaptive thermogenesis.”

In a study where participants were put on a calorie-restricted diet with intense exercise regimen in order to lose large amounts of weight. 6 years later, it was found that most of the participants regained nearly all of theirweight. However, their metabolic rates remained around 500 calories had not gone back up. It was lower than what was expected for their body size.

Many similar studies have found similar results. Metabolism drop due to weight loss can amount to hundreds of calories per day.So it proved that starvation mode is real.It partly explain the fact that why many people end up regaining weight after losing it by diet restriction.

So hormonal effect of short-term fasting can be a key that intermittent fasting may be a good way to adopt in order to achieve a drop in metabolic rate which is caused by long-term calorie restriction.However, till now there is no quality study is available for the long-term effects on metabolic rate of intermittent fasting.

Intermittent fasting helps on to muscle mass

Unfortunately,people lose fat and muscle both when they are aiming to lose weight. Studies have claimed that muscle preservation could be possible by intermittent fasting better than calorie restriction, due to its hormonal effects.

The observed increase in growth hormone during fasting could help muscle mass preservation even if someone is losing weight. Larger and longer studies are needed to find out the effectiveness regarding preservation of lean body mass by intermittent fasting.

Best fasting schedule for weight loss

12 hours fasting a day( The simplest way for the beginners)

Its simple you needs to adhere to a 12-hour fasting window every day.

This intermittent fasting planis suitable option for beginners as the fasting window is small, fasting occurs during sleep, and one can consume same calories each day.

The best fasting period to fast is between 7 p.m. and 7 a.m. Finish your evening meal before 7 p.m. and stop eating until 7 a.m. So you will asleep for much of the time in between.

16 hours fasting Fasting (16:8 or the Leangains diet)

16 hours fating a day while leaving an 8-hour eating window, is known as the 16:8 or the Leangains diet.

Some recommend that women do 14 hours fast and then slowly build their way up to 16 hours, while men can start straight away 16 hrs fasting. This might be helpful for those who did not experienced any benefits from 12 hrs fasting. For this people at 8 pm finish their evening meals, skip breakfast the next day and eat again at noon.

In 2022 a review article figured out that this method with caloric restriction is a way of beneficial method in adults facing obesity. It also found out to have a positive effect on blood sugar processing.

2 days a week fasting (5:2 diet)

The 5:2 diet plan means eating standard amounts of healthy food for 5 days which is followed by reduce calorie intake for the next 2 days.

During this 2 days fasting period, men usually consume 600 calories and women 500 calories.

People usually separate the fasting days in a week. Like hey fast on Monday and Thursday and on the rest of the days they eat regularly. One nonfasting day between fasting days is necessary.

Limited studies are available on the 5:2 diet, known as Fast diet.

A research in 2020 examining different fasting plans figured out that the 5:2 diet(FAST DIET) had no clear ranking when it is compared with the other intermittent fasting plans.

An other randomized controlled trial in 2021, A randomized controlled trial of the 5:2 diet; https://doi.org/10.1371/journal.pone.0258853 found that individuals with obesity on the 5:2( FAST DIET) fasting plan with group support at 6 week experienced a greater weight loss and rated thisplan highly.

However, this effect diminished over the time, with the difference in weight no longer being significant by the end of 1 year.

Intermittent fasting and insulin resistance

Intermittent fasting now a days is a very effective method for weight loss, in addition to this its benefits are far expanded like treating patients with insulin resistance prediabetics, diabetics and other conditions.

It is a proven fact now that intermittent fasting balance out hormone levels and initiates the repair of many vital cells in the human body leading to facilitation of fat burning. Talking broadly it has a significant impact on our metabolic health and insulin levels.

The main driver of fat storage is insulin. When an individual is eating constantly, insulin production is targeted all day long, so people end up having too much insulinand the cells start resisting insulin leading to the body response to make more. The aim here is to find strategies in order to decrease insulin production which will improve insulin resistance.

16 hours fasting period allows body to have rest and helps body to reduce insulin levels significantly. This helps in fat burning and also decreases risk for pre-diabetes and pre-diabetes.

Metabolic Benefits

Once an individual develops insulin resistance it causes increase in the insulin levels putting them at an increased risk of diabetes. That’s why intermittent fasting has its benefits beyond weight reduction. As fasting decreases insulin levels it help people who are struggling with their blood pressure and blood sugar levels and help prediabetic and diabetic individual. People.

A correlation between better insulin control and metabolic responses is seen by multiple researchers., like decrease in inflammation, better gut health and overall improved health even in the absence of significant weight reduction.

This is also observed in individual with strong insulin responses and hormonal irregularities like seen in polycystic ovarian syndrome.(PCOS)

Intermittent fasting is found out to be helpful in individuals with PCOS to control their insulin and hormonal levels, and then improve health and the symptoms related to PCOS.

Fasting for women’s health

In women fasting has shown improved impact on the reproductive and mental health of women. In addition it also prevents and ameliorates cancers and musculoskeletal diseasesof middle-aged and elderly females. Nevertheless, prescribing fastingis a safe medical intervention with lifestyle modifications regimencan improve women’s health to many folds.

Evidences have proved that supervised medical fasting for 7–21 days is an efficacious treatment in, chronic pain syndromes, rheumatic diseases, hypertension, and other metabolic syndromes.

Since centuries fasting is a observed as a common practice traditionlly, culturallyor because of religious reasons.Longo VD, Mattson MP. Fasting: Molecular mechanisms and clinical applications. Cell Metab. 2014;19:181–92. doi: 10.1016/j.cmet.2013.12.008. [DOI] [PMC free article] [PubMed] [Google Scholar][Ref list]

Science based Researches have made it evident that 7-21 days medically supervised fasting is a efficacious treatment for different metabolic syndromes, chronic pain syndromes, rheumatic diseases and hypertension.

There are many diet plansavailable for women’s health but fasting is a missing link and its role needsto be enhancement in health of women.

Fasting and cancer in women

The five most common cancers in women are breast, cervix, lung, colorectum, and stomach. Breast cancer is the second most common cancer worldwide. It’s now a proven fact that fasting is a prognostic tool against cancer and many metabolic syndromes.Keyvani V, Kerachian MA. The effect of fasting on the important molecular mechanisms related to cancer treatment. J Fasting Health. 2014;2:113–8. [Google Scholar][Ref list]

Reproductive health and fasting in women

Reproduction and diet shares a mutual benefecial relationship. In early adulthood, overweight and obesity is identified as an important risk factor for menstrual issues, subfertility and hypertension in pregnancy. In women the most common endocrine disorder is Polycystic ovary syndrome (PCOS). Badawy A, Elnashar A. Treatment options for polycystic ovary syndrome. Int J Womens Health. 2011;3:25–35. doi: 10.2147/IJWH.S11304. [DOI] [PMC free article] [PubMed] [Google Scholar][Ref list]

A recent research on PCOS showed that fasting reduces the chronic sympathetic overactivity. Thisreduces thelevels of stress neurohormone and improves physical and mental health on the other hand short-term caloric restriction increases the luteinizing hormone in obese women with PCOS, which emphasizes that fasting has beneficial for women with ovulatory problems.

Lifestyle changes however is the the first-line of treatment in an evidence-based approach when it comes to the management of women with PCOS and are overweight/obese.Moran LJ, Pasquali R, Teede HJ, Hoeger KM, Norman RJ.

Treatment of obesity in polycystic ovary syndrome: A position statement of the Androgen Excess and Polycystic Ovary Syndrome Society. Fertil Steril. 2009;92:1966–82. doi: 10.1016/j.fertnstert.2008.09.018. [DOI] [PubMed] [Google Scholar][Ref list]

Research has shown that even 5–10% weight loss significantly affects clinical benefits and improves reproductive features like menstrual irregularities, ovulation, and fertility.

In addition and metabolic issues like insulin resistance and risk factors for DM2 and cardiovascular diseases have beneficial affects.Van Dam EW, Roelfsema F, Veldhuis JD, Helmerhorst FM, Frölich M, Meinders AE, et al. Increase in daily LH secretion in response to short-term calorie restriction in obese women with PCOS.

Am J Physiol Endocrinol Metab. 2002;282:E865–72. doi: 10.1152/ajpendo.00458.2001. [DOI] [PubMed] [Google Scholar][Ref list]

Musculoskeletal health and fasting in women

Musculoskeletal differ in nature and ranges from mils ailments of acute nature to lifelong conditions like osteoporosis, osteoarthritis, rheumatoid arthritis, and low back pain. Prevalence of these increases with the increasing age.

Fasting has shown that it effects parathyroid hormone secretion and which found out to be beneficial in improving bone health. The role of circadian rhythm also effectparathyroid hormone and plays a vital role in calcium and phosphate metabolism effecting the bone remodeling process.

Fraser WD, Logue FC, Christie JP, Gallacher SJ, Cameron D, O’Reilly DS, et al. Alteration of the circadian rhythm of intact parathyroid hormone and serum phosphate in women with established postmenopausal osteoporosis. Osteoporos Int. 1998;8:121–6. doi: 10.1007/BF02672507. [DOI] [PubMed] [Google Scholar][Ref list]

7–10 days fasting has shown pain reduction, stiffness, and decreases analgesics dependency compared to the controls in Rheumatoid arthritis patients.Sköldstam L, Larsson L, Lindström FD. Effect of fasting and lactovegetarian diet on rheumatoid arthritis. Scand J Rheumatol. 1979;8:249–55. doi: 10.3109/03009747909114631. [DOI] [PubMed] [Google Scholar][Ref list]

These all fats emphasizes the role of fasting in obviating inflammation, one of the major contributing factors in musculoskeletal diseases. Globally, osteoporosis and its related fractures are of a significant concern. In aging population, morbidity and mortality from fractures is related to low bone mineral density which increases as an individual ages.

Calorie restriction, has been proposed to slow the progression of age-related diseases like obesity, cancer, cardiovascular disorders, osteoporosis and Alzheimer’s disease.Fasting has proved byheterogeneous findingshelps in weight loss and improves body mass index.

Weight reduction will help in diluting the fracture risks and its related comorbidities.Mazidi M, Karimi E, Rezaee P, Nematy M, Salehi M. The effects of Ramadan fasting on body composition. Shiraz E Med J. 2014;15:e19733. [Google Scholar][Ref list]

Metabolic health and fasting in women

The MetS is an important risk factor for cardiovascular disorders and frequently coexists. In 20–30% of middle-aged women, its linked to the development of diabetes and cardiovascular disorders. There is a marked increase in women to develop MetS in menopausal years.

From the pre- to post-menopause stage there is the emergence of different features of the MetS, like

Increased central body fat
A shift towards an atherogenic lipid profile increased (LDL) and triglycerides levels, decreased (HDL), and dense LDL particles
Increased glucose and insulin levels.

Intermittent fasting has evolved as a potential tool for the management of metabolic abnormalities and has shown positive results in various experimental studies.Anson RM, Guo Z, de Cabo R, Iyun T, Rios M, Hagepanos A, et al.

Intermittent fasting dissociates the beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. Proc Natl Acad Sci U S A. 2003;100:6216–20. doi: 10.1073/pnas.1035720100. [DOI] [PMC free article] [PubMed] [Google Scholar][Ref list]

The researchers have that IF has significant cardioprotective actions like, weight reduction by reducing fat tissue mass, heart rate and blood pressure. It improves lipid profile by decreasing total cholesterol and LDL levels and increasing HDL levels.

In addition 4 weeks fasting reduces total body weight, waistindex circumference and body mass index.Reduced waist circumference is correlated with increased insulin sensitivity. These findings emphasizes the role of fasting as an intervention in preventing metabolic dysfunctions in elderly women.

Mental health and Fasting in women

Mental health issues are common It is common is women who undergo menopausal transitions to face mental health issues. 80–85% of women at some points through their perimenopausal and menopausal periods experience unpleasant menopausal symptoms.

The most common of these are irritability, hot flashes,moodiness, night sweat, anxiety, and emotional instability. Many researches have pointed out the positive impacts of fasting on promoting women mental health.

Through different studies it is highlighted thatself- esteem is greatly improved by fasting, which is likely to be helpful in maintaining a positive mental health. Fasting also impacts symptoms of depression and anxiety and improves social well-being. Also in diminishing depression, anxiety and stresslevels fasting has proved its beneficial effects. Many physicians have found out that fasting improves mood in women.

Changes in quality of sleep, neurotransmittersneurotrophic factors synthesis have been observed by nany neurobiological mechanisms by fasting. In short fasting act as a enhancer of mental health.Fond G, Macgregor A, Leboyer M, Michalsen A.

Fasting in mood disorders: Neurobiology and effectiveness. A review of the literature. Psychiatry Res. 2013;209:253–8. doi: 10.1016/j.psychres.2012.12.018. [DOI] [PubMed] [Google Scholar][Ref list]

Intermittent Fasting: Ancient Practice, Modern Health Benefits

Since ancient times fasting has been used as a nonpharmacological intervention by different medical fields for multiple diseases. In spite of its evidence-based therapeutic efficacy in the modern era, it is rarely used as a therapeutic intervention.

It has been used more as a religious regimen than a therapeutic one. Fasting has a major role to play in health during the various phases of life. However, larger randomized control trials are needed to explain its benefits at a wider scale.

Available studies have major limitations like preclinical studies and lesser sample size. Ethical issues on fasting are a major challenge in conducting these wide-scale trials.

Future studies must address these gaps by designing supervised medical fasting techniques for better scientific evidence.

Nevertheless, fasting as a safe medical intervention can be prescribed and can be adopted as a lifestyle regimen to improve human health to several folds.