Can Intermittent Fasting Help Fight Obesity and Improve Metabolism?

Meal time restriction (or intermittent fasting) is a recent dietary trend that has gained a large following in the nutrition world. Its general principle is to insert fixed periods of fasting (usually 12-48 hours) and not restrict nutrition in any other way. Some animal studies show that this is an effective weight loss strategy ¹.   

A recent human study looked at whether intermittent fasting benefits overweight or obese adults ². Researchers observed 116 men and women divided into two groups: one group ate three meals a day at the same time, and the other restricted meal times and ate  ad libitum from noon to 8 p.m., then fasted from 8 p.m. until the next day. The subjects were followed for 12 weeks: their weight, fat mass, lean muscle mass, fasting insulin, fasting glucose, hemoglobin A1c, estimated energy intake, total energy burned, and resting energy burned were recorded.

What is Intermittent Fasting?

Intermittent fasting (IF) is an eating pattern that alternates between fasting and eating periods.

It doesn't tell you what foods you should eat or when you should eat them.

In this regard, it is not a diet in the conventional sense, but is more accurately described as an eating pattern.

Common methods of intermittent fasting include fasting for 16 hours daily or fasting for 24 hours twice a week.

In fact, intermittent fasting is more natural than eating 3-4 (or more) meals a day.

Methods of intermittent fasting

There are several different ways to do intermittent fasting, all of which involve dividing a day or week into periods of eating and fasting.

During fasting periods, you eat very little or nothing at all.

These are the most popular methods:

• The 16/8 Method: Also called Leangains, involves skipping breakfast and limiting eating periods to 8 hours a day, such as 1-9pm. Then you fast for 16 hours in between.
• Eat-Stop-Eat: This involves fasting for 24 hours once or twice a week, such as not eating from dinner one day to dinner the next.
• The 5:2 Diet: With this method, you only eat 500-600 calories for two consecutive days of the week, but eat normally for the next 5 days.

By reducing your calorie intake, all of these methods should lead to weight loss as long as you don't compensate by eating much more during your meal periods.

Many people find the 16/8 method to be the simplest, most sustainable, and easiest to follow. It is also the most popular.

How does it affect your cells and hormones?

When you fast, several things happen in your body at the cellular and molecular level.

For example, your body adjusts hormone levels to make stored body fat easier to recycle.

Your cells also initiate important recycling processes and change gene expression.

Here are some of the changes that occur in your body when you fast:

• Human Growth Hormone (HGH): Growth hormone levels increase dramatically and increase as much as 5-fold. It is useful in reducing fat and increasing muscle mass.
• Insulin: Insulin sensitivity increases and insulin levels drop dramatically. Lower insulin levels make stored body fat more accessible.
• Cellular Repair: When you don't eat, your cells begin cellular repair processes. This involves autophagy, where cells digest and remove old and dysfunctional proteins that accumulate inside cells.
• Gene expression: Changes in gene function associated with longevity and protection against disease.

These changes in hormone levels, cell function, and gene expression are responsible for the health benefits of intermittent fasting.

Health benefits

Here are the main health benefits of intermittent fasting:

• Weight Loss: As mentioned above, intermittent fasting can help you lose weight and belly fat without consciously restricting calories.
• Insulin resistance: Intermittent fasting can reduce insulin resistance, lower blood sugar 3-6%, which should protect against type 2 diabetes.
• Inflammation: Some studies show a reduction in markers of inflammation, which is a major cause of many chronic diseases.
• Heart health: Intermittent fasting can reduce blood sugar and insulin resistance, all risk factors for heart disease.
• Cancer: Studies show that intermittent fasting can prevent cancer.
• Brain health: Intermittent fasting increases brain hormone levels and can help new nerve cells grow. It can also protect against Alzheimer's disease.
• Anti-aging: Intermittent fasting can increase lifespan. Studies have shown that fasting people lived 36-83% longer.

Keep in mind that research is still ongoing. Many studies have been small, short-term, or done in animals. Many questions remain to be answered in higher quality human studies.

Side effects

If you have health problems, consult your doctor before trying intermittent fasting.

This is especially important if:

• You have diabetes.
• You have problems regulating your blood sugar.
• You have low blood pressure.
• You are taking medication.
• You weigh too little.
• You have a history of eating disorders.
• You are a woman trying to conceive.
• You are a woman who has had amenorrhea.
• You are pregnant or breastfeeding.

All that being said, intermittent fasting has an exceptional safety profile. There is nothing dangerous about not eating for a while if you are generally healthy and eating well.

What are the results of intermittent fasting?

Although weight loss was slightly greater in the time-restricted group, the difference in weight loss between the two groups was not significant. In addition, there was no change in fat mass in either group. However, participants in the intermittent fasting group lost more lean muscle mass in the upper and lower extremities, and this rate was significant compared to the control group.

This is the second human study ³ who confirmed that intermittent fasting causes loss of lean muscle mass, a rather alarming trend. Finally, no significant changes in metabolic health indicators or sleep were demonstrated, although a reduction in physical activity (as measured by the Oura ring) was assessed, leading to a reduction in total energy burned.

Overall, this study does not support the benefit of mealtime restriction in the treatment of obesity and, as in the previous study, raises the question of the possible risk of loss of lean muscle mass.   

You will learn more about the body's personal need for minerals or vitamins after taking a free health test "Your Day":

Important:

*In time, pay attention to the signals sent by your well-being;

*Replenish the body with natural minerals or vitamins;

*Enjoy energy and good mood every day!

Literature:

1. Chaix A, Zarrinpar A, Miu P, Panda S. Time-restricted feeding is a preventive and therapeutic intervention against diverse nutritional challenges. Cell Metab 2014;20(6):991-1005. 
2. Lowe D, Wu N, Rohdin-Bibby L, et al. Effects of time-restricted eating on weight loss and other metabolic parameters in women and men with overweight and obesity: The TREAT Randomized Clinical Trial. JAMA Intern Med 2020;180(11):1491-1499. 
3. Harris L, Hamilton S, Azevedo LB, et al. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Evid Synth 2018;16(2):507-547.