Intermittent Fasting: How Does It Work?



Can going for hours, or even a full day, without eating, help you lose weight? Some research suggests that intermittent fasting, a relatively recent eating plan that involves eating during scheduled hours and fasting for others, helps burn fat or lower blood sugar levels.


However, this plan isn’t right for everyone, such as people with diabetes, children and teenagers, women who are breastfeeding, or those with an eating disorder history.

Is regimenting the hours you eat right for you?


An article by Monique Tello, MD, MPH, on the Harvard Health Publishing website about intermittent fasting, offered information about the body and its use of energy and the anatomical idea behind intermittent fasting.

Intermittent fasting aims to let the body’s insulin levels decrease long enough to be able to burn fat.


The article stated that carbohydrates are broken down quickly into sugar. The body uses this for energy. However, if the body’s cells don’t use all of it, it is stored in the body as fat. Insulin allows sugar to enter the body’s cells, including fat cells.


However, between meals, if an individual is not snacking, insulin levels decrease and fat cells release stored sugar to use as energy. If insulin levels decrease, an individual loses weight.


The Harvard Health Publishing article stated that research done on rats showed that intermittent fasting resulted in weight loss, improved blood pressure, better cholesterol, and blood sugar levels. In humans, however, some research showed that intermittent fasting is safe and effective, but about as effective as any other diet.


There are several approaches to intermittent fasting. A daily approach, according to an article on the Johns Hopkins Medicine website, involves eating during a six to eight-hour period per day and fasting for the remaining time. There is also the 5:2 approach, in which people eat regularly for five days per week and eat 500 to 600 calories per day on the remaining two days.


Going too long without eating, such as 24 to 72 hours, can be dangerous and can encourage fat storage, according to the Johns Hopkins Medicine article. When you go too long without eating, the body stores fat in response to starvation.


After 12 hours, the body typically begins burning fat, according to an article on the University of Michigan Health website.


During fasting times, people can consume water, vegetable, chicken, or bone broth. They should not consume soda or beverages with caffeine.


When not fasting, people should eat normally, according to the Johns Hopkins Medicine website.


Generally, people should limit sugars and refined grains, and opt for fruits, vegetables, beans, lentils, whole grains, lean proteins, and healthy fats, according to the Harvard Health Publishing article. They should also avoid snacking and be active throughout the day. The Harvard Health Publishing article recommended trying a simple form of intermittent fasting, such as eating between 7 a.m. and 3 p.m. or 10 a.m. to 6 p.m.


However, the article suggested eating earlier in the day, and not in the evening before bed.


Research shows it can take two to four weeks for the body to adjust to intermittent fasting. Before starting a new diet or eating pattern, people should consult with their doctor.