Many people ask me what’s the best fasting for weight loss. I always said that there is no best fasting because different type of fasting will help you in different way. A little bit confused? So, let me show you what I mean.
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Why Fasting for Weight Loss Can Backfire
When you eat less than you need and you lose weight, your body goes into a starvation mode. To save energy, your metabolism slows down.
When you’re done fasting and you go back to your usual diet, you may regain the weight you lost, and then some.
On a fast, your body adjusts by curbing your appetite, so you will feel less hungry at first. But once you have stopped fasting, your appetite revs back up. You may feel hungrier and be more likely to overeat.
Fasting every other day has similar results. It helps people lose weight, but not for long.
In one study, people who fasted every other day shed weight, even when they ate all they wanted on days when they weren’t fasting. But the weight loss didn’t last over time.
Is Fasting Safe?
Fasting for a few days probably won’t hurt most people who are healthy, provided they don’t get dehydrated.
Your body needs vitamins, minerals, and other nutrients from food to stay healthy. If you don’t get enough, you can have symptoms such as fatigue, dizziness, constipation, dehydration, and not being able to tolerate cold temperatures.
Other people who should not fast include women who are pregnant or breastfeeding, anyone with a chronic disease, the elderly, and children.
Before you go on a new diet, particularly one that involves fasting, ask your doctor if it’s a good choice for you. Several studies show promise of intermittent fasting and several health benefits. Studies of intermittent fasting in humans with chronic disease have resulted in better control of their disease. However, these studies are done only over a period of months. It’s unclear if the benefits would remain for years if the diet is continued throughout life.
You can also ask your doctor for a referral to a registered dietitian, who can show you how to design a healthy eating plan.
IS FASTING GOOD FOR YOU?
Science suggests that intermittent fasting can have a number of potential health benefits besides weight loss. In one study published in the American Journal of Clinical Nutrition(opens in new tab), fasting was shown to reduce the risk of diabetes. In another study from the journal Cell Metabolism(opens in new tab), researchers found intermittent fasting was linked to improved cardiovascular health, including lowered resting heart rate and reduced blood pressure. The researchers also found that no adverse effects occurred even up to six months of regular intermittent fasting.
Fasting has also been shown to help reduce inflammation, with one study(opens in new tab) finding that just one month of daily 12-hour fasts helped lower levels of inflammatory markers in the body.
A recent study(opens in new tab) also found that 14 hours or more of daily fasting for 30 days resulted in changes to gene expression that could promote DNA repair and other health markers for longevity. Studies(opens in new tab) also show fasting can help keep your brain sharp. In one study(opens in new tab) involving a small group of fasting women, intermittent fasting increased the happy hormone serotonin and other brain-boosting factors.
However intermittent fasting may not be beneficial for certain groups of people. According to one study(opens in new tab), intermittent fasting should not be used by children or pregnant women, and another study(opens in new tab) found that women’s periods could be adversely affected if calorie intake is consistently too low.
HOW TO LOSE WEIGHT BY FASTING: WHAT YOU NEED TO KNOW
Fasting is a practice that has been around for thousands of years and is defined as the abstinence from food (or any calories) for a set period of time. Whilst there is a whole range of fasting methods, the best-known and most researched method for weight loss is intermittent fasting, which is an eating pattern that involves cycling between periods of non-eating and eating.
One of the reasons that intermittent fasting has been shown to work for weight loss is because of the overall reduction in calorie consumption that results from extended fasting periods.
Studies have shown intermittent fasting can yield impressive weight loss results. In a review study published in the journal Translational Research(opens in new tab), researchers found that intermittent fasting was able to result in a 1.65 pound per week rate of weight loss, whilst another recent meta study(opens in new tab), reviewing 27 intermittent fasting programs, found participants had a weight loss of 0.8% to 13.0% baseline weight without any serious side effects. They also found that where participants followed the intermittent fasting for longer than 4 weeks, waist circumference decreased by 1.1 inches/3 cm to 3.1 inches/8 cm.
How does intermittent fasting impact the body?
Like many, I was attracted to intermittent fasting not only for the weight management advantages, but also for several other healthful aspects. It makes sense to me that if I am relentlessly consuming food at regular intervals — breakfast, lunch, dinner and evening snacks — I am giving my body a message that digesting food is a priority. Since digestion, especially of dietary fat, takes several hours, the body is actively engaged in the digestion process from breakfast early in the morning through evening snacks and many hours beyond.
As a result, the body gets only a minimal reprieve from digestion and is fasting for just a few hours, at best, late in one’s sleep cycle that is short lived because breakfast soon arrives.
This is an important consideration because the gut contributes to health in many ways, especially when it comes to bolstering the immune system, which occurs during fasting. Going hand-in-hand with increased immune cell production is autophagy, the body’s way of cleaning out damaged cells, in order to regenerate newer, healthier cells. A good analogy for autophagy is taking out the trash or cleaning up debris. The debris in this case is composed of parts of body cells that become damaged and need to be removed so that new cells can be developed.
Fasting also promotes the production of human growth hormone, which helps you shed body fat and hold on to muscle, increasingly more important to health as we age.
How do I do intermittent fasting?
There are several ways to approach intermittent fasting. My approach is to fast daily and consume food only during a narrow window of time from two to four hours. I built up to this gradually, starting with a larger window and progressively reducing is. At about the 18-hour mark of fasting is when the benefits described above kick into gear and rev up.
Here’s what I outline about my typicl daily approach to intermittent fasting in a previous column: I envision what I normally would have had for breakfast and lunch, plus snacks (power bars, nuts, etc.), and consume these “after” my first meal of the day at 6 p.m. I drink black coffee periodically throughout the day, which satisfies me comfortably until my dinner.
And, let me add, if I feel like cheating at night with a treat like a hot-fudge sundae, I don’t hesitate.
In addition, my workouts are great, with no loss of energy, even though I am fasted for many hours prior to working out.
How does intermittent fasting differ from other crash diets?
A readers recently wrote to me about intermittent fasting. He wrote, “I have read your books on nutrition, healthy dieting and exercise, and you rail against crash diets because the lack of nutrients results in the loss of muscle mass. Now, I read about your use of intermittent fasting which reduces caloric intake to zero for prolong periods of time and I wonder, how does this differ from the caloric restriction on a crash diet?”
An insightful question that’s worth exploring.
First, on a crash diet, you severely cut your caloric intake from perhaps 2,000 calories per day to less than half that amount and enter a semi-starvation mode. When you cut caloric intake drastically, the body struggles to sustain your blood sugar, known as glucose, at optimal levels. Blood sugar is critical because the brain depends on glucose as its primary source of fuel, and of course, the brain is the body’s top priority.
Glucose is stored in the liver as glycogen. When you eat “normally,” if blood sugar levels fall, glucose is released from the liver to bring the level back up. However, on a crash diet, the supply of liver glycogen is depleted because the body is in a semi-starvation mode. Thus, when the blood sugar levels falls, the body is alarmed that the liver cannot respond appropriately.
In turn, this causes the body to take emergency action. The hormone cortisol is released which breaks down muscle into proteins that are further broken down into amino acids. Selective amino acids are transported to the liver and converted to glucose that bolsters the blood sugar level. In other words, the body destroys muscle to make glucose and the process is called gluconeogenesis.