How to Fast One Day a Week for Weight Loss

While fasting once a week to lose weight may seem like just another silly fad, the science of fasting backs up the hype. Fasting does not just mean avoiding food, though. A successful program takes a little planning and basic knowledge of how fasting works.

According to the experts at Texas Medical Center, the benefits of intermittent fasting go far beyond simple weight loss. When you deprive your body of calories for 12 to 18 hours, scientists speculate that this causes your neural pathways and your DNA to strengthen and rebuild. Admittedly, TMC says, this has been proven in mice but is still theoretical in humans.

But, the experts at TMC continue, intermittent fasting ​does​ have some proven benefits for people. They do not actually come from the act of fasting on its own, though, so do not think that you can just stop eating and reap all sorts of wonderful effects. That is not how it works.

Any benefits from fasting one day per week come from the fact that you are switching between starving your body and then feeding it again. The influx of calories and nutrients after a fast encourages your body to get the most out of those calories and nutrients that it possibly can.

Experts such as those at TMC believe that back in the caveman days, hunters who could eat well and then go for short periods without food were more likely to survive than those who could not survive short famines.

There are many benefits to intermittent fasting, according to the International Sports Sciences Association (ISSA). Aside from weight loss, benefits of fasting one day a week or for certain hours of each day include:

• Blood sugar levels lowered
• Blood triglyceride levels lowered
• Brain health improved
• Cancer risk lowered
• Heart disease risk reduced
• Inflammation reduced
• Insulin resistance reduced
• LDL cholesterol levels lowered

According to ISSA, fasting one day a week benefits start with fat loss. Intermittent fasting encourages your body to burn fat because it encourages the production of human growth hormone, or HCG, which helps burn fat as well as helping you to burn lean muscle tissue. A reduced insulin response is also helpful in burning fat, ISSA explains.

Intermittent fasting is safe and effective when done properly, but fasting one day per week is not right for everyone, caution the health experts at the Southwest College of Naturopathic Medicine. Because fasting has a profound effect on your blood sugar levels, people with diabetes, especially those on insulin, should not fast.

Others who should be cautious about fasting, Southwest states, are anyone pregnant or nursing, those with low blood pressure and people who have struggled with eating disorders such as anorexia, bulimia or ​orthorexia​ — an addiction to the idea of "clean eating," according to Loma Linda University Health. Being underweight is also a reason to avoid fasting, SCNM reminds you.

Most side effects of fasting are mild, reassures the University of Rochester Medical Center. These can range from headaches and irritability to lack of energy and even feeling cold. You might also find changes in your bowel movements, but mild, temporary changes are normal and no cause for alarm. If you experience drastic changes, consult your physician.

​Read more:​ 13 DOs and DON'Ts of Intermittent Fasting

There are several different ways to approach a fast, ranging from avoiding all foods and beverages for at least 24 hours to limiting your food and beverage intake to a certain number of hours during the day, explain the nutrition experts at Texas Medical Center. Simply avoiding taking in ​any​ calories for a 24-hour period is one of the simpler types of fasts, but it can be difficult if you are new to fasting.

Another type of fast to consider, TMC advises, is to stop eating at 8 p.m. one or two days per week and not eat again until noon the next day. This offers the same benefits as a 24-hour fast, reassures TMC, but without the drawbacks. You can also eat dinner at 6 p.m. and not eat again until dinner the next night, sipping water and herbal teas to keep you from feeling entirely deprived.

If you are not quite ready to embrace a full 24-hour fast from breakfast to breakfast, simply stop eating at 6 p.m. or 8 p.m. and then resume a lean and healthy meal plan the next morning, advise the experts at Colorado State University. Do this no more frequently than one or two days per week to ensure that you are taking in enough calories and nutrition.

​Read more:​ How Eat-Stop-Eat Fasting Works

Fasting once a week to lose weight sounds simple in theory, but it can be a challenge if your fasting day falls on the day of your best friend's wedding, a company picnic or a treasured holiday celebration that revolves around food.

Rather than torture yourself by sipping plain water while you inhale the smoke from your boss's barbecue, give yourself a little breathing room by being flexible. Even the National Institute of Diabetes and Digestive and Kidney Diseases says that it's OK to have occasional treats.

Look at your schedule too. If you work double shifts, are switching from the day shift to the night shift or vice versa, have a new baby or puppy, or have any other reason for lack of sleep, this may not be the time to fast. Lack of sleep affects the hormones that control your hunger levels, reminds the Los Angeles County Department of Health, and can also cause your body to hold on to fat.

Stress can also affect your ability to lose weight, Los Angeles County says. So starting a weekly fast at the same time you start a new job, move to a new place, or are dealing with the effects of a breakup or other loss might not be the most effective choice you can make — both for your physical health and your mental and emotional health. The last thing you want to do is set yourself up for failure.

​Read more:​ The Science behind Emotional Eating: Why We Do it and How to Stop

Choosing to fast one day per week to lose weight is not guaranteed to bring you the results you want, cautions the National Institute on Aging, but if done carefully and knowledgeably, it should also not do you any harm. There are several things to keep in mind as you fast, suggests the NIA.

Make sure that what you eat on nonfasting days is a lean and nutritious diet built around leafy green vegetables, fresh fruits, whole grains, nuts and seeds, lean protein such as chicken and fish, and healthy fats from avocados and olive oils.

It is also important, say the experts at the NIA, to get enough sleep, do some sort of regular exercise and keep up with your social contacts — it is far easier to tackle a challenge such as intermittent fasting if you are well rested and have plenty of emotional support.