Cutting back on caloric intake is the hallmark and best strategy to lose weight. The most common way involves reducing energy by 15-60% of usual caloric intake every day. But there’s another option many people swear by- intermittent fasting. The idea behind this controversial eating plan isn’t exactly a new one. It was used in the early 1900’s to treat disorders such as diabetes and epilepsy and it’s been gaining traction with modern-day dieters since The Fast Diet (aka the 5:2 program) was first published in 2013.
What is intermittent fasting?
There are now various versions of intermittent fasting, but the overarching concept is the same. Eat pretty much whatever you want, but only during a specific time period. There are several different ways of doing intermittent fasting -all of which involve splitting the day or week into eating and fasting periods.
During the fasting periods, you eat either very little or nothing at all.
These are the most popular methods:
- The 16/8 method: Also called the Leangains protocol, involves skipping breakfast and restricting your daily eating period to 8 hours, such as 1–9 p.m. Then you fast for 16 hours in between.
- Eat-Stop-Eat: This involves fasting for 24 hours, once or twice a week, for example by not eating from dinner one day until dinner the next day.
- The 5:2 diet: With this method, you consume only 500–600 calories on two non-consecutive days of the week, but eat normally the other 5 days.
- The Warrior Diet: Fast for 20 hours a day and eat one large meal every night
By reducing your calorie intake, all of these methods should cause weight loss as long as you don’t compensate by eating much more during the eating periods.
Many people find the 16/8 method to be the simplest, most sustainable and easiest to stick to. It’s also the most popular. The warrior diet is obviously the most extreme and shouldn’t be entertained if you have underlying medical issues. All should be cleared by your healthcare provider.
What are the benefits of intermittent fasting?
Intermittent Fasting Increases Several Fat Burning Hormones
Hormones are chemicals that act as messengers. They travel through your body to coordinate complicated functions such as growth and metabolism. They also play an important role in the regulation of your weight. This is because they have a strong influence on your appetite, the number of calories you eat and how much fat you store or burn. Intermittent fasting has been linked to improvements in the balance of some fat burning hormones.
Insulin:
Insulin is one of the main hormones involved in fat metabolism. It tells your body to store fat and also stops your body from breaking fat down. Having chronically high levels of insulin can make it much harder to lose weight. High levels of insulin have also been linked to diseases like obesity, type 2 diabetes, heart disease and cancer. Intermittent fasting has been shown to be just as effective as calorie-restricted diets for lowering your insulin levels. In fact, this eating style could reduce fasting insulin levels by 20–31%.
Human Growth Hormone:
Fasting can cause a rise in blood levels of human growth hormone, an important hormone for promoting fat loss. Some studies have shown that in men, levels of human growth hormone may increase by as much as five-fold while fasting. Increases in blood levels of human growth hormone not only promote fat burning, but they also preserve muscle mass and have other benefits. However, women don’t always experience the same benefits from fasting as men do, and it’s not currently clear if women will see the same rise in human growth hormone.
Norepinephrine:
Norepinephrine, a stress hormone that improves alertness and attention, is involved in the “fight or flight” response. It has a variety of other effects on your body, one of which is telling your body’s fat cells to release fatty acids. Increases in norepinephrine generally lead to larger amounts of fat being available for your body to burn. Fasting leads to a rise in the amount of norepinephrine in your bloodstream.
Short-Term Fasts Boost Metabolism by up to 14%:
Many people believe that skipping meals will cause your body to adapt by lowering its metabolic rate to save energy. It’s well established that very long periods without food can cause a drop in metabolism. However, studies have shown that fasting for short periods can actually increase your metabolism, not slow it down. One study in 11 healthy men found that a 3-day fast actually increased their metabolism by an impressive 14% . This increase is thought to be due to the rise in the hormone norepinephrine, which promotes fat burning.
Does Intermittent Fasting Help To Retain Muscle Mass?
Muscle is metabolically active tissue that helps keep your metabolic rate high. This helps you burn more calories even at rest. Unfortunately, most people lose both fat and muscle when they lose weight. It’s been claimed that intermittent fasting could preserve muscle mass better than calorie restriction due to its effect on fat burning hormones. In particular, the increase in human growth hormone observed during fasting could help preserve muscle mass, even if you’re losing weight. But to date research results have been mixed.
Safety and Side Effects
Hunger is the main side effect of intermittent fasting. You may also feel weak and your brain may not perform as well as you’re used to. This may only be temporary, as it can take some time for your body to adapt to the new meal schedule. If you have a medical condition, you should consult with your healthcare provider before trying any of these intermittent fasting programs.
This is particularly important if you:
- Have diabetes.
- Have problems with blood sugar regulation.
- Have low blood pressure.
- Take medications.
- Are underweight.
- Have a history of eating disorders.
- Are a woman who is trying to conceive.
- Are a woman with a history of amenorrhea.
- Are pregnant or breastfeeding.
Although most studies show that fad diets, do not work in the long run, intermittent fasting appears to be safe for many. There is nothing dangerous about not eating for a while if you’re healthy and well-nourished overall. If you’re not, then it absolutely can be harmful. Once cleared medically, intermittent fasting may help jump start weight loss in order to segue way into a lifestyle that promotes healthy, daily eating, exercising and restful sleep.
Sources:
-ncbi.nlm.nih.gov/pubmed/21410865
-ncbi.nlm.nih.gov/pubmed/29419624
-academic.oup.com/ajcn/article/86/1/7/4633143
-healthline.com/nutrition/intermittent-fasting-guide
-ncbi.nlm.nih.gov/pubmed/2405717
-sciencedirect.com/science/article/pii/S193152441400200X