There are many ways to lose weight, but one of the most popular eating plans encourages people to be aware of what they eat during a certain length of time. For most, they pay attention to what they eat during a couple or more days a week. This weight loss approach is known as intermittent fasting, which has become popular over the last couple of years. There are different ways to fast, but the main idea is to usually eat some of the days of the week and significantly reduce calories on other days. Studies have shown that if you do intermittent fasting correctly it can help with weight loss, improve metabolism health and increase metabolism. It may even help prevent some diseases! Combined with a low carb diet, which we discuss in the Body Reboot book, you could have some incredible weight loss results!

Why Intermittent Fasting Works

Web MD explains why intermittent fasting works and how it can speed along weight loss.

Some plans encourage you to skip food entirely for up to 24 or 36 hours at a time. On others, such as the Every Other Day Diet and the 5:2 Fast Diet, you can have some food but only get about one fourth of your regular calories.

Some research shows that intermittent fasting works – at least in the short term. In some studies, people who followed this diet did lose weight and also had a decrease in some of the markers that show inflammation.

The possible secret behind the diet's health-boosting benefits: Fasting puts your cells under a mild stress. Scientists think that the process of responding to this stress, on your low-calorie days, strengthens cells’ ability to deal with stress and potentially fight off some diseases.

What You Can Eat

Wondering what you’re allowed to eat while fasting? Ditch the Carbs explains:

Believe it or not, there are a few things that you can consume even when fasting! Yay!

Clear liquids (you want to make certain that you are staying hydrated)
Cold/hot tea (no sugar added)
Black coffee (no creamer, sugar, half n half, milk, etc. – just black)
Other non-caloric beverages free of added sugars, etc.
But you have to make fasting work for you. If you cannot give up your morning tea or coffee with milk, try the smallest amount that you can still enjoy your morning cuppa. Drinking only water is the gold standard, but find what works for you and you still get results.

Who is Intermittent Fasting a Good Fit For?

Of course, Time says intermittent fasting is an excellent fit for people who are overweight, and it can also help people who have Parkinson’s or Alzheimer’s.

“Intermittent fasting is a good option for weight loss for overweight and obese people,” says Michelle Harvie, a research dietitian with the Prevent Breast Cancer unit at the Manchester Breast Centre in the UK. Harvie has coauthored several studies on intermittent fasting, and her research has repeatedly shown that it outperforms traditional diets in terms of weight loss, reduced body fat and improved insulin resistance. She’s also found some evidence that intermittent fasting may beat traditional weight-loss plans when it comes to lowering a woman’s risk for breast cancer, and that, at least in rodents, fasting plans may disrupt or counteract the development of neurological diseases like Alzheimer’s and Parkinson’s.

Most of Harvie’s research has examined 5:2 fasting plans—or protocols that restrict calorie intake two days a week while allowing normal eating the other five. But she says there’s also promising research on diets that impose fasting every other day (usually referred to as alternate-day fasting plans), and also on time-restricted fasting, which are diets the restrict daily food consumption to a six- or eight-hour window.

“None of these have been studied head to head, but they all improve health,” says Mark Mattson, chief of the Laboratory of Neurosciences at the National Institute on Aging and a professor of neuroscience at the Johns Hopkins School of Medicine.

How it Affects Your Hormones

Even though intermittent fasting affects your hormones, Healthline explains how that could be a good thing:

Body fat is the body's way of storing energy (calories).

When we don't eat anything, the body changes several things to make the stored energy more accessible.

This has to do with changes in nervous system activity, as well as a major change in several crucial hormones.

Here are some of the things that change in your metabolism when you fast:

Insulin: Insulin increases when we eat. When we fast, insulin decreases dramatically. Lower levels of insulin facilitate fat burning.
Human growth hormone (HGH): Levels of growth hormone may skyrocket during a fast, increasing as much as 5-fold. Growth hormone is a hormone that can aid fat loss and muscle gain, among other things.
Norepinephrine (noradrenaline): The nervous system sends norepinephrine to the fat cells, making them break down body fat into free fatty acids that can be burned for energy.
Interestingly, despite what the 5-6 meals a day proponents would have you believe, short-term fasting may actually increase fat burning.

Two studies have found that fasting for about 48 hours boosts metabolism by 3.6-14%. However, fasting periods that are longer can suppress metabolism.

A study from 1990 found that fasting for around 48 hours increases metabolism by 3.6-14%. However, it’s important to keep in mind that if you were to fast for longer than 48 hours that it could suppress your metabolism.

The effects of 48-h starvation on the physiological responses to a 30-min infusion of epinephrine at 25 ng.min-1.kg body wt-1 were studied in 11 normal-weight healthy young subjects. Starvation led to considerable alterations in basal metabolism including a significant (mean 3.6%) increase in resting metabolic rate. During the infusions, plasma epinephrine concentration rose less in the starved state (+1.47 nmol/l) than in the normally fed state (+1.73 nmol/l) (SE 0.06 nmol/l; P less than 0.05). The maximum increments (mean +/- SE) in heart rate induced by epinephrine were 11.9 +/- 1.3 beats/min in the normally fed state and 20.1 +/- 2.0 beats/min in the starved state (P less than 0.001); the corresponding mean increments in blood glycerol concentration were 0.07 and 0.14 mmol/l (SE 0.01 mmol/l; P less than 0.01). The increase in the metabolic rate above base line during the final 10 min of the epinephrine infusion was 0.58 +/- 0.18 kJ/min in the normally fed state and 0.78 +/- 0.14 kJ/min in the starved state (P less than 0.01). The chronotropic, lipolytic, and thermogenic effects of infused epinephrine were therefore enhanced by prior starvation, despite the lower plasma epinephrine levels.

Similarly, another study from 2000 also found that fasting for 48 hours increased metabolism and thus, helped people lose more weight:

The effects of 48-h starvation on the physiological responses to a 30-min infusion of epinephrine at 25 ng.min-1.kg body wt-1 were studied in 11 normal-weight healthy young subjects. Starvation led to considerable alterations in basal metabolism including a significant (mean 3.6%) increase in resting metabolic rate. During the infusions, plasma epinephrine concentration rose less in the starved state (+1.47 nmol/l) than in the normally fed state (+1.73 nmol/l) (SE 0.06 nmol/l; P less than 0.05). The maximum increments (mean +/- SE) in heart rate induced by epinephrine were 11.9 +/- 1.3 beats/min in the normally fed state and 20.1 +/- 2.0 beats/min in the starved state (P less than 0.001); the corresponding mean increments in blood glycerol concentration were 0.07 and 0.14 mmol/l (SE 0.01 mmol/l; P less than 0.01). The increase in the metabolic rate above base line during the final 10 min of the epinephrine infusion was 0.58 +/- 0.18 kJ/min in the normally fed state and 0.78 +/- 0.14 kJ/min in the starved state (P less than 0.01). The chronotropic, lipolytic, and thermogenic effects of infused epinephrine were therefore enhanced by prior starvation, despite the lower plasma epinephrine levels.

Can it Help With Weight Loss?

Ditch the Carbs discusses how intermittent fasting can lead to weight loss, which is exciting if you’re combining a low carb diet with fasting! See how this eating plan can expedite weight loss and also help you feel better:

While it’s not a guaranteed weight loss plan, intermittent fasting is well known to kick-start weight loss, especially if the scales have stopped moving.

For the most part, weight loss is being accomplished by a dramatic decrease in their caloric daily intake. It is also due to a reduction in glucose and insulin levels which enables you to be in nutritional ketosis. Your body has switched to fat burning mode.

Intermittent fasting can undoubtedly aid in weight loss, and if done correctly also has many health benefits. If you combine it with a low carb diet, you have a higher probability of losing weight as well! At the time of writing this post, we're giving away free copies of the Body Reboot book because it’s our goal to help people reach their weight loss goals! Cover the cost of shipping, and we’ll send you our FREE book. Head to this page TODAY to see if there are any remaining copies.

Sources: Web MD, Ditch the Carbs, Healthline, NCBI: Am J Physiol. 1990, NCBI: Am J Clin Nutr. 2000, Time