Intermittent Fasting For Weight Loss 2022: How It Helps You Lose Weight

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Medically reviewed by Kathy Shattler, MS, RDN

intermittent fasting for weight loss

Intermittent fasting (IF) is becoming a popular lifestyle approach with a lot of interest. In simplest terms, IF is alternating normal eating and restriction times. 

Intermittent fasting (IF) tends to result in fewer calories consumed and metabolically burns excess stored energy. A calorie deficit is an essential foundation for losing weight. There may be some other health benefits to IF as well. 

If you’ve heard about intermittent fasting, meal skipping, or alternate-day fasting and are curious about how it might help your weight goals, we are going to dive into what the facts are right now about this type of diet approach. 

What is an Intermittent Fasting Diet?

Intermittent fasting focuses not on what you eat but on when you eat.  The relative simplicity of intermittent fasting can make it very appealing. There is no calorie counting, tracking food groups, counting macros, or any foods that are considered off-limits.  You simply eat based on your defined schedule, and that’s it.  

There are several theoretical beneficial[1] effects of intermittent fasting. Going long periods without eating forces your body to metabolically switch to burning stored energy for fuel, including stored fat.  It’s a natural fat burner, and thus far, the evidence suggests intermittent fasting for weight loss is effective for both women and men.

In addition, a limited time to eat naturally limits overall calorie intake, resulting in weight reduction. This can lead to an improved risk of cardiovascular disease, reduced blood pressure, and incidence of metabolic syndrome.  Finally, there is evidence that disordered circadian rhythms are linked to chronic disease, and intermittent fasting may positively influence[2] a better-aligned rhythm. 

We all fast to some degree while we sleep.  An intermittent fasting diet usually involves periods of at least 14-16 hours with no food intake.  It may vary depending on which schedule you choose to follow. 

How Does it Work?

First, determine a fasting schedule that works best for you.  We’ll get into the different fasting plans and options shortly to help decide what might work for you. 

Once you’ve determined a schedule, then try to stick with that schedule with as much consistency as possible. 

During your fasting period, no-calorie beverages are allowed.  Water, black coffee, no-calorie sparkling water, or unsweetened tea are all ok.  It is important to stay hydrated while fasting.

During the eating window, there are no set guidelines for what or how much to eat.  Those who adhere to intermittent fasting should eat as they normally would and what they like (within reason, of course). Healthy eating is still important, but there are no rules to stick to.

Types of Intermittent Fasting Plans That Aid Weight Loss

There is no single definition of an intermittent fasting plan. Many variations and regimens exist. Here is a round-up of the most popular intermittent fasting for weight loss schedules you might consider trying:

Time-Restricted Feeding

Time-restricted eating follows a daily pattern of a defined fasting period and defined eating period.  The exact hours for each can vary as well as the stop and start time.  

A 16-hour fast and 8-hour eating period is a common place to start and one that many find manageable. If desired, the time could be further restricted to 18:6 or lessened to 14:10.   The timing of the fast is up to the individual. For example, one could choose their 8-hour eating zone to be 12 pm to 8 pm or 10 am to 6 pm.

5:2 

The 5:2 method is a weekly schedule in which five days you eat normally, and two days of the week you follow a daily calorie restriction.  Some versions of 5:2 define restricted calories as one-quarter of your personal daily needs or simply no more than 500 calories consumed (which is one-quarter of the 2000-calorie diet used for standard nutrition advice).  The user can determine which days are eating days and which are restricted days, although it’s usually not recommended to plan the two fasting days consecutively. 

Alternate Day Fasting 

In the alternate-day fasting plan, every other day is a fast day. On fasting days, calorie intake is typically modified to about 500 calories total, although some versions fully restrict all calories. 

Warrior Diet

The warrior diet was created by fitness specialist Ori Hofmekler in his book first published in 2001. The warrior diet restricts eating to small amounts of fruits and vegetables during the day and a daily 4-hour window in the evening to eat a meal. 

Eat Stop Eat

Eat Stop Eat is also a plan made popular by a book of the same name. This plan promotes a 24-hour fast once or twice weekly. All other days of the week, you eat a healthy diet.  

Pros & Cons of Intermittent Fasting for Weight Loss

Intermittent fasting can be controversial.  And with so many different options, it gets confusing quickly. Let’s start with the benefits of intermittent fasting based on the current research.

Pros

Evidence suggests it can be effective for many in achieving weight loss. A recent review[3] published in 2021 in the Annual Review of Nutrition determined that average body weight reduction for participants ranged from 1-8%. This was true across studies using alternate-day fasting, a 5:2 diet, or time-restricted feeding plans. 

Research also suggests intermittent fasting can improve cardiovascular risk factors[4] and the risk for Type 2 Diabetes[5] while having additional health benefits. You may experience reduced blood pressure, improved insulin resistance, reduced fat mass, and lower cholesterol levels.

There is also some evidence that IF can improve gut health and promote better sleep[6], but stronger research is needed to confirm these claims.  

Anecdotal reports from followers of IF note they feel improved energy and better mental alertness on the plan. This has not been confirmed in research.  

Finally, from an adherence standpoint, the flexibility and sheer amount of regimen options are positive points for intermittent fasting. You have the power to adjust to your schedule or needs and determine what works for you. 

Those who are prone to frequent snacking or mindless eating as a hurdle for weight loss may find fasting particularly helpful to stop those habits when they have a no-eating zone as part of their day or week.

Cons

Depending on which fasting plan was used, it may be more difficult to adhere to long-term for some individuals. One 2020 review[7] study noted dropout rates were higher for those on a fasting eating plan compared to continuous calorie restriction.  

While research thus far has generally concluded that intermittent fasting is a promising method to decrease body weight, it may not be any more effective than a daily caloric restriction. 

For example, a 2022 study[8] published in the New England Journal of Medicine found no additional weight reduction in subjects who followed a continuous calorie restriction with time-restricted eating vs. subjects who only followed a calorie restriction. 

Intermittent fasting has been criticized for promoting or exacerbating disordered eating behaviors.  It is not recommended for those with a history of an eating disorder, but that same 2021 review in the Annual Nutrition Review found no evidence that IF directly causes eating disorders to develop. 

Research is promising regarding the health benefits of IF on the incidence of Type 2 diabetes, but it may not be appropriate for individuals with Type 1 diabetes. Fasting periods may cause very low blood sugar levels that can be dangerous for Type 1 diabetics.  They should consult with their doctor before starting a fasting regimen. Those with Type 2 diabetes aim to control blood sugar levels[9] by burning fat stores, lowering blood sugar levels, and increasing insulin sensitivity with IF.

Individuals can have varied experiences when they fast; some side effects can be common, such as headaches, digestive disturbances, or low energy.

Studies are growing, but most involve small subject groups and a limited time frame for data collection.  It appears to be effective in achieving short-term weight loss results, but long-term efficacy to avoid weight regain needs further investigation. 

How to Do Intermittent Fasting for Weight Loss Effectively?

With so many options to consider, your head may be swimming with how to best try intermittent fasting.  These tips will help ensure your intermittent fasting journey is effective for weight loss, no matter the schedule:

  • Eating a healthy and balanced diet is still key to seeing results. Overindulging or choosing high sugar or high-fat foods when you eat will not be effective in reducing body weight. Many health professionals advise following the Mediterranean Diet during your non-fasting times for the best health effects.
  • Consistency is important. Whatever plan you choose, stick with it day in and day out. Research has shown the best predictor[10] for weight reduction is a plan that you adhere to in the long term.  If your chosen schedule isn’t working for you, try making some adjustments until you find a manageable plan you can stick to.
  • Include physical activity as part of your intermittent fasting eating pattern.  A combination of endurance exercise and strength training will be helpful in maintaining muscle mass during a time of calorie restriction, can further improve cardiovascular risk factors, and speed up the rate of weight loss.
  • Always talk to your doctor about any concerns you are experiencing while following an intermittent fasting regimen. 

For most individuals, intermittent fasting is a safe option[11] to aid your weight management goals that are relatively well-supported in the research at this time. Results are at least similar to traditional calorie-restriction diets, and it can be a practical solution for those who struggle with a complex eating regimen. 


+ 11 sources

Health Canal avoids using tertiary references. We have strict sourcing guidelines and rely on peer-reviewed studies, academic researches from medical associations and institutions. To ensure the accuracy of articles in Health Canal, you can read more about the editorial process here

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  2. Daas, M.C. and de Roos, N.M. (2021). Intermittent fasting contributes to aligned circadian rhythms through interactions with the gut microbiome. Beneficial Microbes, [online] 12(2), pp.147–161. doi:10.3920/bm2020.0149.
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Medically reviewed by:

Lindsey Jerke has over 10 years of experience as a registered dietitian working in the clinical setting and now in the food industry in regulatory compliance.

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