What Happens to Your Body When You Fast for 16 Hours?

Medically Reviewed on 12/21/2021
what are the health benefits of fasting?
When planned well, a 16-hour intermittent fasting diet (16:8 diet plan) provides many long-lasting health benefits, such as the following.

Researchers found that fasting for 16 hours is beneficial to your body as long as you do not have comorbidities. If planned well, a 16-hour intermittent fasting diet provides you with many long-lasting health benefits. It is one of the easy diets to follow. But initially, it will be hard on the body.

Initially, with fasting, the body physiology undergoes changes that include:

  • Hunger and fatigue as the body feel low on the energy from glucose.
  • Gluconeogenesis, a process where glucose is generated from fat stores in the body to provide energy, is initiated.
  • This process of using stored glucose and fat leads to weight loss.
  • During the initial stages of fasting, you feel hungry at the usual times of your meals, as your brain is conditioned in such a manner.
  • Gradually, your body adapts to fasting, and the hunger levels decrease.
  • Having a healthy meal after fasting increases insulin sensitivity.
  • Insulin sensitivity helps in fat loss and protects the body from diseases such as diabetes, high blood pressure, and heart diseases.
  • During the 16-hour fast, your body undergoes a process known as autophagy, a process where the body destroys old or damaged cells in the body.
    • Autophagy recycles the cells that help in the reduction of inflammation in the body and reduces diseases.
    • It also improves the health of the skin and prevents wrinkles, aging, and acne.
    • It improves the immune system and disease-fighting capacity.
    • It also slows down the process of aging of the body.
    • It increases the generation of new brain cells and nerve tissue that increase brain performance and improve memory, mood, and focus.
  • Fasting increases certain proteins in the brain called a brain-derived neurotrophic factor, which helps the brain to adapt and withstand stress. These proteins also increase the production of brain cells and improve their functionality. 
  • According to the National Institutes of Health, fasting may reduce the development of Alzheimer’s disease and Parkinson’s disease or develop protective measures against damage from a stroke.

What are the benefits of 16-hour fasting?

16-hour intermittent fasting is also called a 16:8 diet plan where you consume just water, black coffee, green tea, and other unsweetened beverages. Then, you can eat all of your meals and snacks for the remaining eight hours of the day.

The 16-hour period may appear to belong, but if you're receiving adequate sleep, you should be asleep for around half of that time.

The benefits of a 16:8 intermittent fasting diet include:

  • Weight loss:
    • Weight loss is the ultimate goal for intermittent fasting. According to a study of 40 independent types of research published in Molecular and Cellular Endocrinology, someone weighing slightly over 90 kg could lose 5 percent of their total body weight in 10 weeks on average.
    • According to 2018 research published in the Journal of Nutrition and Healthy Eating, the 16:8 diet plan can help people lose weight without having to count calories, as the eight-hour fast generates the same calorific restriction and weight reduction as the 16:8 diet plan.
  • Improves heart health:
    • Fasting regularly has been related to a longer life and a decreased incidence of heart failure in patients with heart diseases.
    • When done throughout a lifetime, even one day of fasting per month can have a significant impact on heart health.
  • Promotes good sleep:
    • According to research, intermittent fasting may assist to enhance our body's circadian rhythm (sleep-wake cycle) because overeating can induce disturbed sleep, allowing us to sleep better.
  • Reduces stress:
    • The 16:8 diet reduces cortisol (stress hormone) levels and inflammation. It's also beneficial for your mental health because you won't have to cope with a hunger for two days a week.

Those who have tried the 16:8 diet report being significantly more productive during fasting hours and spending less time worrying about food and more time channeling their energy into other beneficial tasks throughout the day.


The Best Diet Tips: How to Lose Weight the Healthy Way See Slideshow

What are the drawbacks of 16-hour fasting?

Though 16:8 fasting is found to be beneficial, there are certain downsides to it, which include:

  • Limiting your intake to only eight hours per day may encourage some people to eat more than normal during meal periods to compensate for the hours spent fasting.
  • This may result in weight gain, digestive issues, and the formation of poor eating habits.
  • 16:8 intermittent fasting may also create short-term negative side effects, such as hunger, weakness, and exhaustion, when you first begin. However, these usually fade once you get into a rhythm.
  • Furthermore, some evidence reports that intermittent fasting affects men and women differently, with animal studies indicating that it may interfere with female fertility and reproduction. However, more human research is needed to assess the impact of intermittent fasting on reproductive health.

In any event, begin gently and consider discontinuing or visiting your doctor if you have any worries or encounter bad effects.

Summary of the 16:8 diet plan

Whether the 16:8 diet achieves a significant weight loss advantage over other diets needs to be established.

  • Some studies have reported practically no difference between persons who practice intermittent fasting and those who track calories and limit their intake of harmful foods.
  • The secret to a long and healthy life is mindful eating, lots of physical activity, and stress management.
Medically Reviewed on 12/21/2021
Image Source: iStock Images

Intermittent Fasting: Is it Right for You?: https://healthblog.uofmhealth.org/wellness-prevention/intermittent-fasting-it-right-for-you

What You Should Know About the 16:8 Diet Before You Start Fasting”: https://www.goodhousekeeping.com/health/diet-nutrition/a27336892/16-8-diet/

What Actually Happens To Your Body During A Fast, Hour By Hour: https://www.mindbodygreen.com/articles/what-happens-when-you-fast